http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/issue/feedFacta Universitatis, Series: Mechanical Engineering2017-12-12T23:19:38+01:00Dr. Dragan Marinkovic, Associate Professorfumeed@junis.ni.ac.rsOpen Journal Systems<div id="yui_3_13_0_1_1384327394083_3606"><em>Facta Universitatis, series: Mechanical Engineering (FU Mech Eng)</em> is an open access peer-reviewed international journal published by the University of Niš (Republic of Serbia). High quality, refereed papers are published three times a year. Papers reporting original theoretical and/or practice oriented research or extended versions of the already published conference papers are all welcome. The scope of the journal covers the<span> whole spectrum of Mechanical Engineering.</span> Papers for publication are selected through peer reviewing to ensure originality, relevance, and readability. In doing that, the objective is not only to keep the high quality of published papers, but also to provide a timely, thorough and balanced review process.</div><div><span>Editor-in-Chief: Dragan Marinković</span></div>http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2398THERMAL BUCKLING ANALYSIS OF FUNCTIONALLY GRADED CIRCULAR PLATE RESTING ON THE PASTERNAK ELASTIC FOUNDATION VIA THE DIFFERENTIAL TRANSFORM METHOD2017-12-09T11:34:20+01:00Fatemeh Farhatniazh_farhat@yahoo.comMahsa Ghanbari-Mobarakehmahsa.ghanbari99@yahoo.comSaeid Rasouli-Jazisaeid.rasouli@iaukhsh.ac.irSoheil Oveissisoheil.oveissi@gmail.com<p>In this paper, we propose a thermal buckling analysis of a functionally graded (FG) circular plate exhibiting polar orthotropic characteristics and resting on the Pasternak elastic foundation. The plate is assumed to be exposed to two kinds of thermal loads, namely, uniform temperature rise and linear temperature rise through thickness. The FG properties are assumed to vary continuously in the direction of thickness according to the simple power law model in terms of the volume fraction of two constituents. The governing equilibrium equations in buckling are based on the Von-Karman nonlinearity. To obtain the critical buckling temperature, we exploit a semi-numerical technique called differential transform method (DTM). This method provides fast accurate results and has a short computational calculation compared with the Taylor expansion method. Furthermore, some numerical examples are provided to consider the influence of various parameters such as volume fraction index, thickness-to-radius ratio, elastic foundation stiffness, modulus ratio of orthotropic materials and influence of boundary conditions. In order to predict the critical buckling temperature, it is observed that the critical temperature can be easily adjusted by appropriate variation of elastic foundation parameters and gradient index of FG material. Finally, the numerical results are compared with those available in the literature to confirm the accuracy and reliability of the DTM to determine the critical buckling temperature.</p>2017-12-09T11:34:20+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2311CRANIOFACIAL STRESS PATTERNS AND DISPLACEMENTS AFTER ACTIVATION OF HYRAX DEVICE: FINITE ELEMENT MODELLING2017-12-09T11:34:19+01:00Sergei Bosiakovbosiakovsm@gmail.comAnastasiya Vinokurovajaneraven@mail.ruAndrei Dostadummmyyy@yahoo.com<p>Rapid maxillary expansion is employed for the treatment of cross-bite and deficiency of transversal dimension of the maxilla in patients with and without cleft of palate and lip. For this procedure, generally, different orthodontic appliances and devices generating significant transversal forces are used. The aim of this study is the finite-element analysis of stresses and displacements of the skull without palate cleft and the skull with unilateral and bilateral cleft after activation of the Hyrax orthodontic device. Two different constructions of the orthodontic device Hyrax with different positions of the screw relative palate are considered. In the first case, the screw is in the occlusal horizontal plane, and in the other, the screw is located near the palate. Activation of the orthodontic device corresponds to the rotation of the screw on one-quarter turn. It is established that the screw position significantly affects the distributions of stresses in skull and displacements of the cranium without palate cleft and with unilateral or bilateral palate cleft. Stresses in the bone structures of the craniums without cleft and with cleft are transferred from the maxilla to the pterygoid plate and pharyngeal tubercle if the screw displaces from the occlusal plane to the palate. Depending on the construction of the orthodontic appliance, the maxilla halves in the transversal plane are unfolded or the whole skull is entirely rotated in the sagittal plane. The stresses patterns and displacements of the skull with bilateral palate cleft are almost unchanged after activation of the orthodontic devices with different positions of the screw, only magnitudes of stresses and displacements are changed. The obtained results can be used for design of orthodontic appliances with the Hyrax screw, as well as for planning of osteotomies during the surgical assistance of the rapid maxillary expansion.</p>2017-12-09T11:34:19+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2830COMPUTERIZED RADIAL ARTERY PULSE SIGNAL CLASSIFICATION FOR LUNG CANCER DETECTION2017-12-09T11:34:19+01:00Zhichao Zhangrainkissthesun@126.comAnton Umekanton.umek@fe.uni-lj.siAnton Kosanton.kos@fe.uni-lj.siPulse diagnosis, the main diagnosis method in traditional Chinese medicine, is a non-invasive and convenient way to check the health status. Doctors usually use three fingers to feel three positions; Cun, Guan, and Chi of the wrist pulse, to diagnose the body’s healthy status. However, it takes many years to master the pulse diagnosis. This paper aims at finding the best position for acquiring wrist-pulse-signal for lung cancer diagnosis. In our paper, the wrist-pulse-signals of Cun, Guan, and Chi are acquired by three optic fiber pressure sensors of the same type. Twelve features are extracted from the signals of these three positions, respectively. Eight classifiers are applied to detect the effectiveness of the signal acquired from each position by classifying the pulse signals of healthy individuals and lung cancer patients. The results achieved by the proposed features show that the signal acquired at Cun is more effective for lung cancer diagnosis than the signals acquired at Guan and Chi.2017-12-09T11:34:19+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/3368INFLUENCE OF THE CHANGING LOCAL CLIMATE ON WIND POTENTIALS OF MOUNT KOPAONIK2017-12-09T11:34:18+01:00Predrag Živkovićpzivkovic@masfak.ni.ac.rsMladen Tomićtomicmladen@yahoo.comDragana Dimitrijevićdragana.dimitrijevic@masfak.ni.ac.rsMirko Dobrnjacdobrnjac.mirko@gmail.comIvana Kecmanivana933@hotmail.comObtaining all acceptable locations is one of the main tasks for siting wind turbines. The economic factors are usually very limiting. Very thorough analyses are needed in order to ensure the project finalization. Nevertheless, even after all the steps are made, some problems may occur. One of them is the real status of the winds in the so-called climatology period. This paper focuses on the influences of the changing winds after the preliminary estimations are done. The estimations are obtained using the WAsP simulation software. The results are compared in terms of quality and quantity of the wind data and capacity factor. Finally, an economic analysis is done.2017-12-09T11:34:18+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/3349EXPERIMENTAL INVESTIGATION OF THE CONVECTIVE HEAT TRANSFER IN A SPIRALLY COILED CORRUGATED TUBE WITH RADIANT HEATING2017-12-09T11:34:17+01:00Milan Đorđevićmilan.djordjevic@pr.ac.rsVelimir Stefanovićveljas@masfak.ni.ac.rsMića Vukićmicav@masfak.ni.ac.rsMarko Mančićmarkomancic@yahoo.comThe Archimedean spiral coil made of a transversely corrugated tube was exposed to radiant heating in order to represent a heat absorber of the parabolic dish solar concentrator. The main advantage of the considered innovative design solution is a coupling effect of the two passive methods for heat transfer enhancement - coiling of the flow channel and changes in surface roughness. The curvature ratio of the spiral coil varies from 0.029 to 0.234, while water and a mixture of propylene glycol and water are used as heat transfer fluids. The unique focus of this study is on specific boundary conditions since the heat flux upon the tube external surfaces varies not only in the circumferential direction, but in the axial direction as well. Instrumentation of the laboratory model of the heat absorber mounted in the radiation field includes measurement of inlet fluid flow rate, pressure drop, inlet and outlet fluid temperature and 35 type K thermocouples welded to the coil surface. A thermal analysis of the experimentally obtained data implies taking into consideration the externally applied radiation field, convective and radiative heat losses, conduction through the tube wall and convection to the internal fluid. The experimental results have shown significant enhancement of the heat transfer rate compared to spirally coiled smooth tubes, up to 240% in the turbulent flow regime.2017-12-09T11:34:17+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/3351DETERMINATION OF AVERAGED AXISYMMETRIC FLOW SURFACES AND MERIDIAN STREAMLINES IN THE CENTRIFUGAL PUMP USING NUMERICAL SIMULATION RESULTS2017-12-09T11:34:16+01:00Jasmina Bogdanović-Jovanovićbminja@masfak.ni.ac.rsDragica Milenkovićdragica.milenkovic@masfak.ni.ac.rsŽivojin Stamenkovićzikas@masfak.ni.ac.rsŽivan Spasićzivans@masfak.ni.ac.rsOne of the most important aims<em> </em>in the turbo pump design is to achieve an optimal design of the pump impeller. The basic assumption in the design procedure of the impeller is that of the axisymmetric fluid flow. It can be confirmed or disputed by using the method presented in the paper, which uses the results of numerical simulation of fluid flow in the pump impeller. The method is actually a procedure for determining averaged axisymmetric flow surfaces and meridian streamlines. Furthermore, according to the obtained streamlines, a correction of the impeller blade geometry can be made (if the streamlines deviate significantly from the assumed axisymmetric ones). It is also possible to calculate the specific works of the elementary stages and compare them with the previous assumptions. The pump impeller torque can be calculated as well.2017-12-09T11:34:16+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2032FORCED CONVECTION DRYING OF INDIAN GROUNDNUT: AN EXPERIMENTAL STUDY2017-12-12T23:19:38+01:00Ravinder Kumar Sahdevravindersahdev.uiet@mdurohtak.ac.inMahesh Kumarmkshandilya1@gmail.comAshwani Kumar Dhingraashwani_dhingra1979@rediffmail.com<p>In this paper, convective and evaporative heat transfer coefficients of the Indian groundnut were computed under indoor forced convection drying (IFCD) mode. The groundnuts were dried as a single thin layer with the help of a laboratory dryer till the optimum safe moisture storage level of 8 – 10%. The experimental data were used to determine the values of experimental constants C and n in the Nusselt number expression by a simple linear regression analysis and consequently, the convective heat transfer coefficient (CHTC) was determined. The values of CHTC were used to calculate the evaporative heat transfer coefficient (EHTC). The average values of CHTC and EHTC were found to be 2.48 W/m<sup>2 o</sup>C and 35.08 W/m<sup>2 o</sup>C, respectively. The experimental error in terms of percent uncertainty was also estimated. The experimental error in terms of percent uncertainty was found to be 42.55%. The error bars for convective and evaporative heat transfer coefficients are also shown for the groundnut drying under IFCD condition.</p>2017-12-09T11:34:15+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/3350NUMERICAL COMPUTATION AND PREDICTION OF ELECTRICITY CONSUMPTION IN TOBACCO INDUSTRY2017-12-09T11:34:13+01:00Mirjana Lakovićlmirjana@masfak.ni.ac.rsIvan Pavlovićpivan@masfak.ni.ac.rsMiloš Banjacmbanjac@mas.bg.ac.rsMilica Jovićmilica.jovic@masfak.ni.ac.rsMarko Mančićmarkomancic@masfak.ni.ac.rs<p class="Abstract">Electricity is a key energy source in each country and an important condition for economic development. It is necessary to use modern methods and tools to predict energy consumption for different types of systems and weather conditions. In every industrial plant, electricity consumption presents one of the greatest operating costs. Monitoring and forecasting of this parameter provide the opportunity to rationalize the use of electricity and thus significantly reduce the costs. The paper proposes the prediction of energy consumption by a new time-series model. This involves time series models using a set of previously collected data to predict the future load. The most commonly used linear time series models are the AR (Autoregressive Model), MA (Moving Average) and ARMA (Autoregressive Moving Average Model). The AR model is used in this paper. Using the AR (Autoregressive Model) model, the Monte Carlo simulation method is utilized for predicting and analyzing the energy consumption change in the considered tobacco industrial plant. One of the main parts of the AR model is a seasonal pattern that takes into account the climatic conditions for a given geographical area. This part of the model was delineated by the Fourier transform and was used with the aim of avoiding the model complexity. As an example, the numerical results were performed for tobacco production in one industrial plant. A probabilistic range of input values is used to determine the future probabilistic level of energy consumption.</p>2017-12-09T11:34:13+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1905RADIAL FORCE IMPACT ON THE FRICTION COEFFICIENT AND TEMPERATURE OF A SELF-LUBRICATING PLAIN BEARING2017-12-12T23:16:28+01:00Nada Bojićnalemfkg@gmail.comDragan Milčićdragan.milcic@gmail.comMilan Banićmilan.banic@outlook.comMiroslav Mijajlovićmijajlom@masfak.ni.ac.rsRužica Nikolićruzicarnikolic@yahoo.comSelf-lubricating bearings are available in spherical, plain, flanged journal, and rod end bearing configurations. They were originally developed to eliminate the need for re-lubrication, to provide lower torque and to solve application problems where the conventional metal-to-metal bearings would not perform satisfactorily, for instance, in the presence of high frequency vibrations. Among the dominant tribological parameters of the self-lubricating bearing, two could be singled out: the coefficient of friction and temperature. To determine these parameters, an experimental method was applied in this paper. By using this method, the coefficient of friction and temperature were identified and their correlation was established. The aim of this research was to determine the effect of radial force on tribological parameters in order to predict the behavior of sliding bearings with graphite in real operating conditions.2017-12-09T11:34:11+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2839A NOVEL HYBRID METHOD FOR NON-TRADITIONAL MACHINING PROCESS SELECTION USING FACTOR RELATIONSHIP AND MULTI-ATTRIBUTIVE BORDER APPROXIMATION METHOD2017-12-11T18:30:18+01:00Prasenjit Chatterjeeprasenjit2007@gmail.comSupraksh Mondalspmondal@gmail.comSoumava Boralboral.ju@gmail.comArnab Banerjeearnabbanerjee31@yahoo.inShankar Chakrabortys_chakraborty00@yahoo.co.in<p>Selection of the most appropriate non-traditional machining process (NTMP) for a definite machining requirement can be observed as a multi-criteria decision-making (MCDM) problem with conflicting criteria. This paper proposes a novel hybrid method encompassing factor relationship (FARE) and multi-attributive border approximation area comparison (MABAC) methods for selection and evaluation of NTMPs. The application of FARE method is pioneered in NTMP assessment domain to estimate criteria weights. It significantly condenses the problem of pairwise comparisons for estimating criteria weights in MCDM environment. In order to analyze and rank different NTMPs in accordance with their performance and technical properties, MABAC method is applied. Computational procedure of FARE-MABAC hybrid model is demonstrated while solving an NTMP selection problem for drilling cylindrical through holes on non-conductive ceramic materials. The results achieved by FARE-MABAC method exactly corroborate with those obtained by the past researchers which validate the usefulness of this method while solving complex NTMP selection problems.</p>2017-12-09T11:34:11+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2590DETERMINATION OF RESIDUAL STRESS IN THE RAIL WHEEL DURING QUENCHING PROCESS BY FEM SIMULATION2017-12-12T23:14:11+01:00Miloš Miloševićmmilos@masfak.ni.ac.rsAleksandar Miltenovićaleksandar.miltenovic@masfak.ni.ac.rsMilan Banićmilan.banic@outlook.comMiša Tomićmisa.tomic@masfak.ni.ac.rsResidual stresses of the rail wheels are influenced by heat treatment during the manufacturing process. The quenching process during the manufacturing results in the residual stresses within the rail wheel that may be dangerous for the rail wheel during its operation. Determination of the residual stress in the rail wheel is important for understanding the damage mechanisms and their influence on the proper work of rail wheels. This paper presents a method for determining the residual stresses in the rail wheel during the quenching process by using the directly coupled thermal-structural analysis in ANSYS software.2017-12-09T11:34:10+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2835CASTING IMPROVEMENT BASED ON METAHEURISTIC OPTIMIZATION AND NUMERICAL SIMULATION2017-12-09T11:34:09+01:00Radomir Radišaradomir.radisa@li.rsNedeljko Dučićnedeljko.ducic@ftn.kg.ac.rsSrećko Manasijevićsrecko.manasijevic@gmail.comNemanja Markovićnemmke@yahoo.comŽarko Ćojbašićzcojba@ni.ac.rsThis paper presents the use of metaheuristic optimization techniques to support the improvement of casting process. Genetic algorithm (GA), Ant Colony Optimization (ACO), Simulated annealing (SA) and Particle Swarm Optimization (PSO) have been considered as optimization tools to define the geometry of the casting part’s feeder. The proposed methodology has been demonstrated in the design of the feeder for casting Pelton turbine bucket. The results of the optimization are dimensional characteristics of the feeder, and the best result from all the implemented optimization processes has been adopted. Numerical simulation has been used to verify the validity of the presented design methodology and the feeding system optimization in the casting system of the Pelton turbine bucket.2017-12-09T11:34:09+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/3295A NEW WINCH CONSTRUCTION FOR SMOOTH CABLE WINDING/UNWINDING2017-12-09T11:34:08+01:00Mirjana Filipovićmirjana.filipovic@pupin.rsLjubinko Kevacljubinko.kevac@gmail.comNew constructive solutions of the winches for single-row radial multi-layered cable smooth winding/unwinding are described. Two new structural solutions of winches are defined. The nonlinear phenomenon of a cable smooth winding/unwinding process on the winch by using one of the two proposed constructive solutions is defined and analyzed. To facilitate understanding of this concept, the cable winding/unwinding process on only one winch is analyzed. The obtained variables which characterize the kinematics of the cable smooth winding/unwinding process are nonlinear and smooth. This result is important because the systems for the smooth cable winding/unwinding process on the winch could be parts of any cable driven mechanism. These systems can be used in various fields of human activity. For the verification of the presented theoretical contributions, a novel software package named SMOWIND – OW has been developed using MATLAB.2017-12-09T11:34:08+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/3361METHOD OF CONVERSION OF HIGH- AND MIDDLE-SPEED DIESEL ENGINES INTO GAS DIESEL ENGINES2017-12-09T11:34:08+01:00Mikhail G. Shatrovmikl-shatrov@yandex.ruVladimir V. Sinyavskisinvlad@mail.ruAndrey Yu. Dunina.u.dunin@yandex.ruIvan G. Shishlovastra510@yandex.ruAndrey V. Vakulenkoengener_avto@yandex.ruThe paper aims at the development of fuel supply and electronic control systems for boosted high- and middle-speed transport engines. A detailed analysis of different ways of converting diesel engine to operate on natural gas was carried out. The gas diesel process with minimized ignition portion of diesel fuel injected by the Common Rail (CR) system was selected. Electronic engine control and modular gas feed systems which can be used both on high- and middle-speed gas diesel engines were developed. Also diesel CR fuel supply systems were developed in cooperation with the industrial partner, namely, those that can be mounted on middle-speed diesel and gas diesel engines. Electronic control and gas feed systems were perfected using modeling and engine tests. The high-speed diesel engine was converted into a gas diesel one. After perfection of the gas feed and electronic control systems, bench tests of the high-speed gas diesel engine were carried out showing a high share of diesel fuel substitution with gas, high fuel efficiency and significant decrease of NO<sub>х</sub> and СО<sub>2</sub> emissions.2017-12-09T11:34:08+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/3243BICYCLE HELMET DESIGN AND THE VIRTUAL VALIDATION OF THE IMPACT, AERODYNAMICS AND PRODUCTION PROCESS2017-12-09T11:34:07+01:00Bojan Boshevskibosevskibojan6694@live.comIle Mircheskiile.mircheski@mf.edu.mkThis paper presents the development process of a bicycle helmet through individual research, creation, presentation and analysis of the results of the most important product development stages. The quality of the development and manufacturing process of the protective equipment for extreme sports is an imperative for a successful product and its flawless function. The design of the bicycle helmet is made following the rules of the design in order to create a well-founded and functional product. After creating design sketches, a virtual prototype was developed in "SolidWorks" using the required ergonomic dimensions. 3D printed model of the human head with adapted ergonomic dimensions and the designed bicycle helmet was developed in order to verify the applied ergonomic measures. The virtual model will be used as an input in the finite element analysis of the helmet impact test based on the EN1078 standard and the aerodynamic simulations executed in "SolidWorks Simulation and Flow Simulation", for verification of the impact and aerodynamic properties. Virtual testing of aerodynamic features and the ability of the bicycle helmet to allow ventilation of the user's head indicate that the helmet performs its function in the desired way. Also, the virtual prototype will be used for the production process simulation in "SolidWorks Plastics" in order to analyze the production of the bicycle helmet. The polycarbonate helmet outer shell is subject to a number of simulations for the sake of analyzing the production process in order to obtain the desired characteristics of the polycarbonate outer shell and to avoid the disadvantages that occur in the manufacturing process. The main goal of this paper is to develop a safety bicycle helmet with improved ergonomic, validation of impact, aerodynamic characteristics and production process in order to produce a high quality product for mass use.2017-12-09T11:34:07+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2973A CAD-BASED CONCEPTUAL METHOD FOR SKULL PROSTHESIS MODELLING2017-12-09T02:14:33+01:00Marcelo Rudekmarcelo.rudek@pucpr.brYohan B. Gumielyohan_bg@hotmail.comOsiris Canciglierir Jrosiris.canciglieri@pucpr.brNaomi Asofunaomi_asofu@hotmail.comGerson L. Bichinhogerson.bichinho@gmail.comThe geometric modeling of a personalized part of the tissue built according to individual morphology is an essential requirement in anatomic prosthesis. A 3D model to fill the missing areas in the skull bone requires a set of information sometimes unavailable. The unknown information can be estimated through a set of rules referenced to a similar yet known set of parameters of the similar CT image. The proposed method is based on the Cubic Bezier Curves descriptors generated by the de Casteljou algorithm in order to generate a control polygon. This control polygon can be compared to a similar CT slice in an image database. The level of similarity is evaluated by a meta-heuristic fitness function. The research shows that it is possible to reduce the amount of points in the analysis from the original edge to an equivalent Bezier curve defined by a minimum set of descriptors. A study case shows the feasibility of method through the interoperability between the prosthesis descriptors and the CAD environment.2017-11-25T23:29:08+01:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2794ALTERNATIVE METHOD FOR ON SITE EVALUATION OF THERMAL TRANSMITTANCE2017-11-15T06:53:32+01:00Aleksandar Jankovićaleksandar.jankovic@aggf.unibl.orgBiljana Antunovićbiljana.antunovic@aggf.unibl.orgLjubiša Preradovićljubisa.preradovic@aggf.unibl.orgThermal transmittance or U-value is an indicator of the building envelope thermal properties and a key parameter for evaluation of heat losses through the building elements due to heat transmission. It can be determined by calculation based on thermal characteristics of the building element layers. However, this value does not take into account the effects of irregularities and degradation of certain elements of the envelope caused by aging, which may lead to errors in calculation of the heat losses. An effective and simple method for determination of thermal transmittance is in situ measurement, which is governed by the ISO 9869-1:2014 that defines heat flow meter method. This relatively expensive method leaves marks and damages surface of the building element. Furthermore, the final result is not always reliable, in particular when the building element is light or when the weather conditions are not suitable. In order to avoid the above mentioned problems and to estimate the real thermal transmittance value an alternative experimental method, here referred as the natural convection and radiation method, is proposed in this paper. For determination of thermal transmittance, this method requires only temperatures of inside and outside air, as well as the inner wall surface temperature. A detailed statistical analysis, performed by the software package SPSS ver. 20, shows several more advantages of this method comparing to the standard heat flow meter one, besides economic and non-destructive benefits.2017-08-02T15:54:15+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/3039MICROSTRUCTURE AND MICROMECHANICS OF SHALE ROCKS: CASE STUDY OF MARCELLUS SHALE2017-11-15T06:52:47+01:00Hui Duhdu4@lsu.eduKristen Carpenterkcarp17@lsu.eduDavid HuiDHui@uno.eduMileva Radonjicmileva@lsu.edu<p class="Abstract">Shale rocks play an essential role in petroleum exploration and production because they can occur either as source rocks or caprocks depending on their mineralogical composition and microstructures. More than 60% of effective seals for geologic hydrocarbon bearing formations as natural hydraulic barriers constitute of shale caprocks. The effectiveness of caprock depends on its ability to immobilize fluids, which include a low permeability and resilience to the in-situ formation of fractures as a result of pressurized injection. The alteration in sealing properties of shale rocks is directly related to the differences in their mineralogical composition and microstructure.</p><p class="Abstract">Failure of the shale starts with deterioration at micro/nanoscale, the structural features and properties at the micro/nanoscale can significantly impact the durability performance of these materials at the macroscale, therefore, study at micro/nanoscale becomes necessary to get better understanding of the hydraulic barriers materials to prevent failure and enhance long-term geologic storage of fluids.</p><p class="Abstract">Indentation tests were conducted at both micro and nanometer level on Marcellus shale samples to get the mechanical properties of bulk and individual phase of the multiphase materials. The mechanical properties map were created based on the nano indentation results and the properties of each individual phase can be correlated with bulk response in the multiphase composite; the effect of each component on the microstructure and bulk mechanical properties can be better understood.</p>2017-08-02T15:54:14+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2856DETERMINATION OF IMPORTANT PARAMETERS FOR PATENT APPLICATIONS2017-11-15T06:50:29+01:00Dušan Markovićdusanmarkovictc@gmail.comDalibor Petkovićdalibortc@gmail.comVlastimir Nikolićvnikolic@masfak.ni.ac.rsMiloš Milovančevićmilos.milovancevic@gmail.comNebojša Denićnebojsa.denic@pr.ac.rs<p>This research study is an analysis of patent applications based on different input parameters. Nine patent indicators for describing patent applications are retrieved from the World Bank database. The method of ANFIS (adaptive neuro fuzzy inference system) is applied to selecting the most important parameters for patent applications. The inputs are: charges for the use of intellectual property for payments and receipts, research and development expenditure, trademark applications for residents and nonresidents, researchers in research and development (R&D), technicians in R&D and high-technology exports. As the ANFIS outputs, patent applications for nonresidents and residents are considered. The results show that the combination of research and development expenditure and technicians in R&D is the most influential combination of input parameters for patent applications.</p>2017-08-02T15:54:13+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2880THE MONOSPIRAL MOTORISED CABLE REEL IN CRANE APPLICATIONS2017-11-15T06:51:47+01:00Vojkan Kostićvojkan.kostic@elfak.ni.ac.rsNebojša Mitrovićnebojsa.mitrovic@elfak.ni.ac.rsBojan Bankovićbojan.bankovic@elfak.ni.ac.rsMilutin Petronijevićmilutin.petronijevic@elfak.ni.ac.rsThe main consideration of any reeling system is the effect it has on cable tensions and hence cable life. This paper explains the relationship of reel torque to cable tensions and the reasons why this relationship is so important. Such system is characterized by variable parameters, primarily a variable moment of inertia and a variable diameter of the coiled cable. For these reasons, in order to ensure proper dimensioning of the drive, it is necessary to know the motor torques that need to be developed as a function of the coiled cable. The motor should be able to develop the required torques in a very wide speed range. It is shown that for properly sizing the motor it is necessary take into account the dynamics of the cable reel drive. In this paper monospiral motorized cable reel for winding power cable in crane applications with frequency converter fed induction motor is analyzed. Also, the equipment selection procedure for the real crane with concrete data is shown. Experimental results are recorded during the crane commissioning in real condition.2017-08-02T15:54:13+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2860SIMULATION OF FRICTIONAL DISSIPATION UNDER BIAXIAL TANGENTIAL LOADING WITH THE METHOD OF DIMENSIONALITY REDUCTION2017-10-15T22:20:38+02:00Andrey V. Dimakidav18@yandex.ruRoman Pohrtdummy12345891@yahoo.comValentin L. Popovv.popov@tu-berlin.deThe paper is concerned with the contact between the elastic bodies subjected to a constant normal load and a varying tangential loading in two directions of the contact plane. For uni-axial in-plane loading, the Cattaneo-Mindlin superposition principle can be applied even if the normal load is not constant but varies as well. However, this is generally not the case if the contact is periodically loaded in two perpendicular in-plane directions. The applicability of the Cattaneo-Mindlin superposition principle guarantees the applicability of the method of dimensionality reduction (MDR) which in the case of a uni-axial in-plane loading has the same accuracy as the Cattaneo-Mindlin theory. In the present paper we investigate whether it is possible to generalize the procedure used in the MDR for bi-axial in-plane loading. By comparison of the MDR-results with a complete three-dimensional numeric solution, we arrive at the conclusion that the exact mapping is not possible. However, the inaccuracy of the MDR solution is on the same order of magnitude as the inaccuracy of the Cattaneo-Mindlin theory itself. This means that the MDR can be also used as a good approximation for bi-axial in-plane loading.2017-08-02T15:54:12+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2797THE INFLUENCE OF VISCOELASTICITY ON VELOCITY-DEPENDENT RESTITUTIONS IN THE OBLIQUE IMPACT OF SPHERES2017-10-15T22:20:37+02:00Emanuel Willerte.willert@tu-berlin.deStephan Kusches.kusche@tu-berlin.deValentin L. Popovv.popov@tu-berlin.de<p class="Abstract">We analyse the oblique impact of linear-viscoelastic spheres by numerical models based on the Method of Dimensionality Reduction and the Boundary Element Method. Thereby we assume quasi-stationarity, the validity of the half-space hypothesis, short impact times and Amontons-Coulomb friction with a constant coefficient for both static and kinetic friction. As under these assumptions both methods are equivalent, their results differ only within the margin of a numerical error. The solution of the impact problem written in proper dimensionless variables will only depend on the two parameters necessary to describe the elastic problem and a sufficient set of variables to describe the influence of viscoelastic material behaviour; in the case of a standard solid this corresponds to two additional variables. The full solution of the impact problem is finally determined by comprehensive parameter studies and partly approximated by simple analytic expressions.</p>2017-08-02T15:54:11+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2916FEATURES OF THE Σ5 AND Σ9 GRAIN BOUNDARIES MIGRATION IN BCC AND FCC METALS UNDER SHEAR LOADING – A MOLECULAR DYNAMICS STUDY2017-11-15T06:44:49+01:00Andrey I. Dmitrievdmitr@ispms.ruAnton Yu. Nikonovdummy12345891@yahoo.comMolecular dynamics simulation of metallic bicrystals has been carried out to investigate the behavior of the symmetrical tilt grain boundaries under shear loading. Σ5 and Σ9 grain boundaries in Ni and α-Fe were analyzed. It is found that behavior of the defect depends not only on the structure of boundaries but also on the type of crystal lattice. In particular it is shown that under external stress the grain boundary (GB) behaves differently in the BCC and FCC metal. A comparison of the values of displacement of various types of GB due to their migration caused by shear deformation is carried out. The results can help us to understand the features of the plastic deformation development in nanoscale polycrystals under shear loading.2017-08-02T15:54:11+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2849REMOTE CONTROL OF THE MECHATRONIC REDESIGNED SLIDER-CRANK MECHANISM IN SERVICE2017-11-15T06:49:39+01:00Miša Tomićmisa.tomic@masfak.ni.ac.rsMiloš Miloševićmmilos@masfak.ni.ac.rsNevena Tomićnenatomic@gmail.comNenad D. Pavlovićpavlovic@masfak.ni.ac.rsVukašin Pavlovićvuxa86@gmail.com<p class="Abstract">Slider-crank mechanisms are used in many machines where there is a need to transform rotary motion into translation, and vice versa. Implementation of the control into a mechanical assembly of the slider-crank mechanism offers a wide range of applications of such controlled mechanism in mechatronic systems. This paper shows an example of the remote control of the angular velocity of the crank in a mechatronic redesigned slider-crank mechanism in order to achieve the desired motion of the slider. The remote control is achieved over the Internet connection and the appropriate software which is executed in the user’s internet browser. The aim of this paper is to present the applied control algorithm as well as to explain advantages of the possibility to remotely run a mechatronic redesigned slider-crank mechanism in service. This is done through an example of using a controlled slider-crank mechanism in a remote laboratory experiment.</p>2017-08-02T15:54:10+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2832DECOUPLING CONTROL OF TITO SYSTEM SUPPORTED BY DOMINANT POLE PLACEMENT METHOD2017-11-15T06:48:24+01:00Novak N. Nedićnedic.n@mfkv.kg.ac.rsSaša Lj. Prodanovićsasa.prodanovic77@gmail.comLjubiša M. Dubonjićdubonjic.lj@mfkv.kg.ac.rsAppropriate approach to the nature of systems is a significant precondition for its successful control. An always actual issue of its mutual coupling is considered in this paper. A multivariable system with two-inputs and two-outputs (TITO) is in the focus here. The dominant pole placement method is used in trying to tune the PID controllers that should support the decoupling control. The aim is to determine parameters of the PID controllers which, in combination with decoupler, can obtain a good dynamical behavior of the system. Therefore, this kind of the centralized analytically obtained controller is used for object control. Another goal is to simplify the tuning procedure of PID controllers and enlarge the possibility for introducing the given approach into practice. But the research results indicate that the proposed procedure leads to the usage of P controllers because they enable the best performances for the considered object. Also, it is noticed that some differences from the usual rules in selection of the dominant poles gives better results. The research is supported by simulations and, therefore, the proposed method effectiveness, regarding the system behavior quality, is presented on several examples.2017-08-02T15:54:09+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2827AUTOMOTIVE APPLICATIONS OF EVOLVING TAKAGI-SUGENO-KANG FUZZY MODELS2017-11-15T06:47:26+01:00Radu-Emil Precupradu.precup@aut.upt.roStefan Preitldummy12340@yahoo.comClaudia-Adina Bojan-Dragosdummy12340@yahoo.comMircea-Bogdan Radacdummy12340@yahoo.comAlexandra-Iulia Szedlak-Stineandummy12340@yahoo.comElena-Lorena Hedreadummy12340@yahoo.comRaul-Cristian Romandummy12340@yahoo.comThis paper presents theoretical and application results concerning the development of evolving Takagi-Sugeno-Kang fuzzy models for two dynamic systems, which will be viewed as controlled processes, in the field of automotive applications. The two dynamic systems models are nonlinear dynamics of the longitudinal slip in the Anti-lock Braking Systems (ABS) and the vehicle speed in vehicles with the Continuously Variable Transmission (CVT) systems. The evolving Takagi-Sugeno-Kang fuzzy models are obtained as discrete-time fuzzy models by incremental online identification algorithms. The fuzzy models are validated against experimental results in the case of the ABS and the first principles simulation results in the case of the vehicle with the CVT.2017-08-02T15:54:08+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2877ROBOT LEARNING OF OBJECT MANIPULATION TASK ACTIONS FROM HUMAN DEMONSTRATIONS2017-11-15T06:46:33+01:00Maria Kyrarinimkyrar@iat.uni-bremen.deMuhammad Abdul Haseebhaseeb@iat.uni-bremen.deDanijela Ristić-Durrantristic@iat.uni-bremen.deAxel Gräserag@iat.uni-bremen.de<p class="Abstract">Robot learning from demonstration is a method which enables robots to learn in a similar way as humans. In this paper, a framework that enables robots to learn from multiple human demonstrations via kinesthetic teaching is presented. The subject of learning is a high-level sequence of actions, as well as the low-level trajectories necessary to be followed by the robot to perform the object manipulation task. The multiple human demonstrations are recorded and only the most similar demonstrations are selected for robot learning. The high-level learning module identifies the sequence of actions of the demonstrated task. Using Dynamic Time Warping (DTW) and Gaussian Mixture Model (GMM), the model of demonstrated trajectories is learned. The learned trajectory is generated by Gaussian mixture regression (GMR) from the learned Gaussian mixture model. In online working phase, the sequence of actions is identified and experimental results show that the robot performs the learned task successfully.</p>2017-08-02T15:54:06+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2577MODELLING AND CONTROL OF H-SHAPED RACING QUADCOPTER WITH TILTING PROPELLERS2017-10-15T22:20:37+02:00Ahmed Alkamachiamrk1978@gmail.comErgun Ercelebiercelebi@gantep.edu.trTraditional quadcopter suffers terribly from its underactuation which implies the coupling between the rotational and the translational motion. In this paper, we present a quadcopter with dynamic rotor tilting capability in which the four propellers are allowed to tilt together around their arm axis. The proposed model provides leveled forward/backward horizontal motion and therefore, ensures a correct view of the onboard camera, and increases the vehicle speed by reducing the air drag. The rotor tilt mechanism also provides an instant high speed in the forward or reverse direction and offers a quick and solid air brake to restrain that fast moving speed. The nonlinear dynamical model for the quadcopter under consideration is derived using Newton-Euler formalization. A control strategy is then proposed aimed to control the altitude, attitude, and the forward speed of the obtained model. Finally, a numerical simulation is used to integrate the system model with the controller and to test the system performance. Simulation results are reported to demonstrate the advantages of the proposed novel configuration.2017-08-02T15:54:05+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/3026NOISE CONTROL OF VEHICLE DRIVE SYSTEMS2017-11-15T06:46:00+01:00Ulrich Gabbertulrich.gabbert@ovgu.deFabian Duvigneaufabian.duvigneau@ovgu.deStefan Ringwelskistefan.ringwelski@ovgu.deThe paper presents an overall simulation approach to control the noise emission of car engines at a very early stage of the design process where no real prototypes are available. The suggested approach combines different physical models and couples different software tools such as multi-body analysis, fluid dynamics, structural mechanics, magneto-electrodynamics, thermodynamics, acoustics and control as well. The general overall simulation methodology is presented first. Then, this methodology is applied to a combustion engine in order to improve its acoustical behavior by passive means, such as changing the stiffness and the use of damping materials to build acoustic and thermal encapsulations. The active control by applying piezoelectric patch actuators at the oil sump as the noisiest part of the engine is discussed as well. The sound emission is evaluated by hearing tests and a mathematical prediction model of the human perception. Finally, it is shown that the presented approach can be extended to electric engines, which is demonstrated at a newly developed electric wheel hub motor.<em></em><br /><em></em>2017-08-02T15:54:05+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/3069FOREWORD2017-10-15T22:20:38+02:00Vlastimir Nikolićvlastimir.nikolic@junis.ni.ac.rsDragan Marinkovićdragan.marinkovic@junis.ni.ac.rsForeword to the issue dedicated to the SAUM 2016 conference.2017-08-02T15:54:04+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2209FROM ART TO ENGINEERING: A TECHNICAL REVIEW ON THE PROBLEM OF VIBRATING CANVAS PART I: EXCITATION AND EFFORTS OF VIBRATION REDUCTION2017-10-15T22:20:39+02:00Kerstin Krachtkkracht@gmx.netThomas Kletschkowskithomas.kletschkowski@haw-hamburg.de<p>Cultural assets are witnesses of past times with versatile worth. The irreplaceability of those treasures of art makes their protection our major task. This article reflects the commitment and results of 40 years of conservators’ research to protect canvas - objects of cultural heritage - particularly from mechanical loads. It gives a classification of mechanical loads that act upon canvas during transport, exhibition and storing in depot. Furthermore, it gives an overview of different approaches which were used over years to protect canvas from various mechanical loads. This article tends to bridge the gap between restorers’ knowledge and methods and concepts known from engineering dynamics. Restorers’ first steps using engineers’ methods are brought up and the necessity of theoretical modeling which has not started so far are pointed out.</p>2017-04-04T00:00:00+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2453IMPLEMENTATION OF THE LEAN-KAIZEN APPROACH IN FASTENER INDUSTRIES USING THE DATA ENVELOPMENT ANALYSIS2017-10-15T22:20:40+02:00Sunil Kumarsunil.panchal2007@gmail.comAshwani Kumar Dhingraashwani_dhingra1979@rediffmail.comBhim Singhbhimsingh2008@gmail.comThis research paper is an attempt to improve the quality system of ten small scale fastener manufacturing industries through the implementation of the Lean-Kaizen approach using the Data Envelopment Analysis (DEA) Charnes Cooper & Rhodes (CCR) model with constant returns to scale (CRS). Output maximization is taken as the objective function to identify the percentage scope of improvements. The data is collected by paying personal visits to the selected industries for three inputs (manpower, maintenance, and training of employees) and two outputs (quality, on-time delivery) of their quality system. The DEA CCR model is applied to identify efficiency scores of the quality system by taking the most efficient industry as a benchmark for the rest of the organizations. The Lean-Kaizen approach is applied to identify waste / non-value added activities in outputs of the selected industries. Four Kaizen events are proposed to eliminate waste / non-value added activities in their quality system. The data collected after the Kaizen events are further analyzed by the DEA CCR model. The improvements in efficiency scores of the selected industries are presented as findings in this research paper. Two fastener industries became 100% efficient while the rest of the organizations reported 8% to 49% improvements in their efficiency scores of the quality system. The conclusions are made as the Lean-Kaizen using DEA is found to be an effective approach to improve the quality system of fastener industries. This study will be beneficial for researchers, practitioners and academicians for tackling the inefficiencies in the organization.2017-04-04T00:00:00+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2733MULTILAYERED PLATE ELEMENTS WITH NODE-DEPENDENT KINEMATICS FOR THE ANALYSIS OF COMPOSITE AND SANDWICH STRUCTURES2017-10-15T22:20:40+02:00Stefano Valvanostefano.valvano@polito.itErasmo Carreraerasmo.carrera@polito.itIn this paper a new plate finite element (FE) for the analysis of composite and sandwich plates is proposed. By making use of the node-variable plate theory assumptions, the new finite element allows for a simultaneous analysis of different subregions of the problem domain with different kinematics and accuracy, in a global/local sense. In particular higher-order theories with an Equivalent-Single-Layer (ESL) approach are simultaneously used with advanced Layer-Wise (LW) models. As a consequence, the computational costs can be reduced drastically by assuming refined theories only in those zones/nodes of the structural domain where the resulting strain and stress states present a complex distribution. On the contrary, computationally cheaper, low-order kinematic assumptions can be used in the remaining parts of the plate where a localized detailed analysis is not necessary. The primary advantage of the present variable-kinematics element and related global/local approach is that no ad-hoc techniques and mathematical artifices are required to mix the fields coming from two different and kinematically incompatible adjacent elements, because the plate structural theory varies within the finite element itself. In other words, the structural theory of the plate element is a property of the FE node in this present approach, and the continuity between two adjacent elements is ensured by adopting the same kinematics at the interface nodes. According to the Unified Formulation by Carrera, the through-the-thickness unknowns are described by Taylor polynomial expansions with ESL approach and by Legendre polynomials with LW approach. Furthermore, the Mixed Interpolated Tensorial Components (MITC) method is employed to contrast the shear locking phenomenon. Several numerical investigations are carried out to validate and demonstrate the accuracy and efficiency of the present plate element, including comparison with various closed-form and FE solutions from the literature<em>.</em>2017-04-04T00:00:00+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/619APPLICATION OF THE PERFORMANCE SELECTION INDEX METHOD FOR SOLVING MACHINING MCDM PROBLEMS2017-10-15T22:20:39+02:00Dušan Petkovićdulep@masfak.ni.ac.rsMiloš Madićmadic@masfak.ni.ac.rsMiroslav Radovanovićmirado@masfak.ni.ac.rsValentina Gečevskavalentina.gecevska@mf.edu.mkComplex nature of machining processes requires the use of different methods and techniques for process optimization. Over the past few years a number of different optimization methods have been proposed for solving continuous machining optimization problems. In manufacturing environment, engineers are also facing a number of discrete machining optimization problems. In order to help decision makers in solving this type of optimization problems a number of multi criteria decision making (MCDM) methods have been proposed. This paper introduces the use of an almost unexplored MCDM method, i.e. performance selection index (PSI) method for solving machining MCDM problems. The main motivation for using the PSI method is that it is not necessary to determine criteria weights as in other MCDM methods. Applicability and effectiveness of the PSI method have been demonstrated while solving two case studies dealing with machinability of materials and selection of the most suitable cutting fluid for the given machining application. The obtained rankings have good correlation with those derived by the past researchers using other MCDM methods which validate the usefulness of this method for solving machining MCDM problems.2017-04-04T00:00:00+02:00Copyright (c) 2017 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1667AN APPLICATION OF MULTICRITERIA OPTIMIZATION TO THE TWO-CARRIER TWO-SPEED PLANETARY GEAR TRAINS2017-10-15T22:20:39+02:00Jelena Stefanović-Marinovićjelena_s_m@yahoo.comSanjin Trohasanjin.troha@gmail.comMiloš Milovančevićmilovancevic@masfak.ni.ac.rs<p class="Abstract"><strong></strong>The objective of this study is the application of multi-criteria optimization to the two-carrier two-speed planetary gear trains. In order to determine mathematical model of multi-criteria optimization, variables, objective functions and conditions should be determined. The subject of the paper is two-carrier two-speed planetary gears with brakes on single shafts. Apart from the determination of the set of the Pareto optimal solutions, the weighted coefficient method for choosing an optimal solution from this set is also included in the mathematical model.</p>2017-04-04T00:00:00+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2094DEEP DRAWING TECHNOLOGY WITH WALL IRONING IN MASS PACKAGING INDUSTRY2017-10-15T22:20:39+02:00Saša Ranđelovićsassa@masfak.ni.ac.rsMladomir Milutinovićmladomil@uns.ac.rsVladislav Blagojevićvlada@masfak.ni.ac.rsAluminum is a metal that is being increasingly used in the packaging industry in the modern metal forming technology, but it also provides a good opportunity for effective advertising and product promotion. Processing technologies for aluminum plastic deformation ensure superior packaging that meets the most rigorous demands in the food, pharmaceutical, chemical, and other industries. It is the case of mass production with very little material loss that offers the possibility of multiple recycling. On the other hand, today's products for general purpose consumers cannot be imagined without aggressive advertising that has a major impact on customers. Modern graphics techniques for printing images and different basic surfaces offer great opportunities that manufacturers use widely in the promotion and sale of their products.2017-04-04T00:00:00+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2199A THEORETICAL-EXPERIMENTAL APPROACH FOR ELASTO-DAMPING PARAMETERS ESTIMATION OF CONE INERTIAL CRUSHER MOUNTING2017-10-15T22:20:39+02:00Rosen Mitrevrosenm@tu-sofia.bgSimeon Savovss.ss@abv.bg<p class="Abstract">The present paper deals with estimation of the elasto-damping parameters of a cone inertial crusher mounting. The numerical values of these parameters are crucial for accurate reproduction of the machine vibrational behavior and dynamical model adequacy. Due to the significant difficulties arising during the purely theoretical determination of the stiffness and damping parameters of the rubber vibroisolators it is well-suited to use a theoretical-experimental approach. The developed approach is based on the theoretical determination of the mounting stiffness parameters as a function of two experimentally measured natural frequencies of the mechanical system. The crusher is represented as a six degrees of freedom system with two planes of symmetry. By using the system characteristic polynomial, the theoretical derivation of mathematical relationships for the mechanical system natural frequencies as a function of stiffness, inertial and geometrical parameters is performed. A good agreement is shown when comparing the experimental and the theoretical results for the system kinematical characteristics.</p>2017-04-04T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1955FUNCTION K - AS A LINK BETWEEN FUEL FLOW VELOCITY AND FUEL PRESSURE, DEPENDING ON THE TYPE OF FUEL2017-10-15T22:20:39+02:00Boban Nikolićnboban@masfak.ni.ac.rsMiloš Jovanovićmilosjovanovic@open.telekom.rsMiloš Miloševićmmilos@masfak.ni.ac.rsSaša Milanovićmsasa@masfak.ni.ac.rsRegarding the application of vegetable oil based fuels in diesel engines, it is necessary to fully examine and understand the processes which take place in fuel delivery systems, namely, the processes of injection, mixture formation and combustion as well as emission characteristics. The paper provides an analysis of fuel flow in high pressure tubes of the fuel injection system, with the aim of determining function K as a link between fuel flow velocity and fuel pressure, and observing the influence of certain physical characteristics of the fuel upon the given function. The analysis presents the speed of sound and density, as fuel characteristics which affect the K function. The paper determines the speed of sound, density and bulk modulus for four fuels (pure rapeseed oil RO, biodiesel B100, a mixture of biodiesel and diesel B50, and diesel D), and forms appropriate K functions for each fuel in the pressure range from the atmospheric one to 1600 bar.2017-04-04T00:00:00+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1972IMPLANT MATERIAL SELECTION USING EXPERT SYSTEM2017-10-15T22:20:39+02:00Miloš Ristićmilos.ristic@vtsnis.edu.rsMiodrag Manićmiodrag.manic@masfak.ni.ac.rsDragan Mišićmisicdr@gmail.comMiloš Kosanovićmilos.kosanovic@vtsnis.edu.rsMilorad Mitkovićmitkovic@gmail.com<p class="Abstract"><span lang="EN-GB">Most certainly, in the field of medicine there is a great contribution of new techniques and technologies, which is reflected in an entire system of health care services. Customized implants are both fully geometrically and topologically adjusted so as to meet the needs of individual patients, thus making each implant unique. Their production requires joint efforts of a multidisciplinary team of different profile experts who combine their knowledge in the Implant knowledge model. Thus, we develop an expert system which should help or replace humans in the process of Implant material selection. This paper gives an overview of the expert system concept for the given problem. Its task is to carry out a selection of biomaterial (or class of material) for a customized implant. The model significantly improves the efficiency of preoperative planning in orthopaedics.</span></p>2017-04-04T00:00:00+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2259THERMAL EFFECT ON FREE VIBRATION AND BUCKLING OF A DOUBLE-MICROBEAM SYSTEM2017-10-15T22:20:39+02:00Marija Stamenković Atanasovs_marija86@yahoo.comDanilo Karličićdanilozmaj@gmail.comPredrag Kozićkozicp@yahoo.comGoran Janevskigocky.jane@gmail.comThe paper investigates the problem of free vibration and buckling of an Euler-Bernoulli double-microbeam system (EBDMBS) under the compressive axial loading with a temperature change effect. The system is composed of two identical, parallel simply-supported microbeams which are continuously joined by the Pasternak’s elastic layer. Analytical expressions for the critical buckling load, critical buckling temperature, natural frequencies and frequencies of transverse vibration of the EBDMBS represented by the ratios are derived and validated by the results found in the literature. Also analytical expressions are obtained for various buckling states and vibration-phase of the EBDMBS. The temperature change effect is assumed to have an influence on both the microbeams. The length scale parameter, temperature change effect, critical buckling load, thickness/material parameter, Pasternak’s parameter and Poisson’s effect are discussed in detail. Also, as a clearer display of the thermo-mechanical response of EBDMBS, the paper introduces a critical scale load ratio of the modified and the local critical buckling loads in low-temperature environs. Numerical results show that the critical buckling temperatures for classical theories are always higher than the critical buckling temperature for MCST systems.2017-04-04T00:00:00+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2682NORMAL LINE CONTACT OF FINITE-LENGTH CYLINDERS2017-10-15T22:20:40+02:00Qiang Liqiang.li@tu-berlin.deValentin L. Popovv.popov@tu-berlin.deIn this paper, the normal contact problem between an elastic half-space and a cylindrical body with the axis parallel to the surface of the half-space is solved numerically by using the Boundary Element Method (BEM). The numerical solution is approximated with an analytical equation motivated by an existing asymptotic solution of the corresponding problem. The resulting empirical equation is validated by an extensive parameter study. Based on this solution, we calculate the equivalent MDR-profile, which reproduces the solution exactly in the framework of the Method of Dimensionality Reduction (MDR). This MDR-profile contains in a condensed and easy-to-use form all the necessary information about the found solution and can be exploited for the solution of other related problems (as contact with viscoelastic bodies, tangential contact problem, and adhesive contact problem.) The analytical approximation reproduces numerical results with high precision provided the ratio of length and radius of the cylinder are larger than 5. For thin disks (small length-to-radius ratio), the results are not exact but acceptable for engineering applications.2017-04-04T00:00:00+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2694A 3-NODE PIEZOELECTRIC SHELL ELEMENT FOR LINEAR AND GEOMETRICALLY NONLINEAR DYNAMIC ANALYSIS OF SMART STRUCTURES2017-10-15T22:20:40+02:00Gil Ramagil.rama@tu-berlin.deComposite laminates consisting of passive and multi-functional materials represent a powerful material system. Passive layers could be made of isotropic materials or fiber-reinforced composites, while piezoelectric ceramics are considered here as a multi-functional material. The paper is focused on linear and geometrically nonlinear dynamic analysis of smart structures made of such a material system. For this purpose, a linear 3-node shell element is used. It employs the Mindlin-Reissner kinematics and the discrete shear gap (DSG) technique to alleviate the transverse shear locking effects. The electric potential is assumed to vary linearly through the thickness for each piezoelectric layer. A co-rotational formulation is used to handle the geometrically nonlinear effects. A number of examples involving actuator and sensor application of piezoelectric layers are considered. For the validation purposes, the results available in the literature and those computed in Abaqus are used as a reference.2017-04-04T00:00:00+02:00Copyright (c) 2017 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2329ADHESION EFFECTS WITHIN THE HARD MATTER – SOFT MATTER INTERFACE: MOLECULAR DYNAMICS2017-10-15T22:20:41+02:00Alexey Tsukanova.a.tsukanov@yandex.ruSergey Psakhiedummyx@yahoo.comIn the present study three soft matter – hard matter systems consisting of different nanomaterials and organic molecules were studied using the steered molecular dynamics approach in order to reveal regularities in the formation of organic-inorganic hybrids and the stability of multimolecular complexes, as well as to analyze the energy aspects of adhesion between bio-molecules and layered ceramics. The combined process free energy estimation (COPFEE) procedure was used for quantitative and qualitative assessment of the considered heterogeneous systems. Interaction of anionic and cationic amino acids with the surface of a [Mg4Al2(OH)122+ 2Cl–] layered double hydroxide (LDH) nanosheet was considered. In both cases, strong adhesion was observed despite the opposite signs of electric charge. The free energy of the aspartic amino acid anion, which has two deprotonated carboxylic groups, was determined to be –45 kJ/mol for adsorption on the LDH surface. For the cationic arginine, with only one carboxylic group and a positive net charge, the energy of adsorption was –26 kJ/mol, which is twice higher than that of chloride anion adsorption on the same cationic nanosheet. This fact clearly demonstrates the capability of “soft matter” species to adjust themselves and fit into the surface, minimizing energy of the system. The adsorption of protonated histamine, having no carboxylic groups, on a boehmite nanosheet is also energetically favorable, but the depth of free energy well is quite small at 3.6 kJ/mol. In the adsorbed state the protonated amino-group of histamine plays the role of proton donor, while the hydroxyl oxygens of the layered hydroxide have the role of proton acceptor, which is unusual. The obtained results represent a small step towards further understanding of the adhesion effects within the hard matter – soft matter contact zone.2016-12-08T00:00:00+01:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2391FOREWORD2017-10-15T22:20:41+02:00Dragan Marinkovićdragan.marinkovic@junis.ni.ac.rs<p>Foreword to the thematic issue entitled:</p><p><em>TRIBOLOGY AND CONTACT MECHANICS IN BIOLOGICAL AND MEDICAL APPLICATIONS</em></p><em></em>2016-12-08T00:00:00+01:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2176INDENTATION OF FLAT-ENDED AND TAPERED INDENTERS WITH POLYGONAL CROSS-SECTIONS2017-10-15T22:20:40+02:00Qiang Liqiang.li@tu-berlin.deValentin L. Popovv.popov@tu-berlin.deUsing the Boundary Element Method, we numerically study the indentation of prismatic and tapered indenters with polygonal cross-sections. The contact stiffness of punches with flat bases in the form of a triangle and a square as well as a number of higher-order polygons is determined. In particular, the classical results of King (1987) for indenters with triangle and square base shapes are revised and more precise numerical results are provided. For tapered indenters, the equivalent transformed profile used in the Method of Dimensionality Reduction (MDR) is determined. It is shown that the MDR-transformed profile of polygon-based indenters with power function side is given by the power function with the same power; it differs from the 3D profile only by a constant coefficient. These coefficients are listed in the paper for various types of indenters, in particular for pyramidal and paraboloid ones. The determined MDR-transformed profiles can be used for study of other contact problems such as tangential contact, normal contact with elastomers, and, in an approximate way, to adhesive contacts.2016-12-08T00:00:00+01:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2275THE JKR-ADHESIVE NORMAL CONTACT PROBLEM OF AXISYMMETRIC RIGID PUNCHES WITH A FLAT ANNULAR SHAPE OR CONCAVE PROFILES2017-10-15T22:20:40+02:00Emanuel Willerte.willert@tu-berlin.deQiang Liqiang.li@tu-berlin.deValentin L. Popovv.popov@tu-berlin.deThe JKR-adhesive frictionless normal contact problem is solved for the flat annular and the conical or spherical concave rigid punch indenting an elastic half space. The adhesive solution can be derived analytically from the non-adhesive one, the latter one being calculated by the boundary element method. It is found that the annular flat punch will always start to detach at the outer boundary. The pull-off forces for both concave punch shapes almost do not depend on the pull-off boundary regime and can be significantly larger than the pull-off force for the cylindrical flat punch.2016-12-08T00:00:00+01:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2307TANGENTIAL DISPLACEMENT INFLUENCE ON THE CRITICAL NORMAL FORCE OF ADHESIVE CONTACT BREAKAGE IN BIOLOGICAL SYSTEMS2017-10-15T22:20:40+02:00Iakov A. Lyashenkonabla04@ukr.netThe dependencies of the critical components of normal and tangential forces corresponding to the contact breakage between a parabolic indenter and an elastic half-space have been determined taking into account adhesive interaction. In order to describe the adhesive contact, the method of dimensionality reduction (MDR) and the modified rule of Heß taking into account tangential displacements have been used. The influence of the surface energy depending on the indenter separation angle has been studied.2016-12-08T00:00:00+01:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2324MODIFYING AND EXPANDING THE SIMULATION OF WEAR IN THE SPHERICAL JOINT WITH A POLYMERIC COMPONENT OF THE TOTAL HIP PROSTHESIS2017-10-15T22:20:40+02:00Vladimir Pakhaliukvpakhaliuk@gmail.comAleksandr Poliakovalex_polyakov@inbox.ruMikhail Kalininkalininsev@mail.ruYevgenii Pashkovpashkov@sevsu.ruPavel Gadkovde1taman@yandex.uaThe existing model of wear, based on the classical Archard equation, in the spherical joint of a total hip prosthesis comprising an acetabular cup of ultra-high molecular weight polyethylene (UHMWPE) in combination with a metal or ceramic femoral head is modified and expanded. With this model, studies are conducted using the finite element analysis in terms of cumulative linear and volumetric wear for the ISO 14242-1 demands and additionally for the conditions during walking gait. Also they are carried out for the head diameter of 28 mm at the constant and the variable wear factor, where the variable wear factor is adopted from the modified formula for the dependence on the contact pressure.2016-12-08T00:00:00+01:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2327NUMERICAL STUDY OF STRESS-STRAIN LOCALIZATION IN THE TITANIUM SURFACE MODIFIED BY AN ELECTRON BEAM TREATMENT2017-10-15T22:20:40+02:00Ruslan Balokhonovrusy@ispms.tsc.ruVarvara Romanovadummyx@yahoo.comAlexey Panindummyx@yahoo.comSergey Martynovdummyx@yahoo.comMarina Kazachenokdummyx@yahoo.com<span style="font-family: 'Times New Roman','serif'; font-size: 10pt; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;" lang="EN-US">Numerical simulation is performed to investigate the mesoscale stress-strain localization in a surface-modified commercial titanium alloy. The calculated crystalline microstructure corresponds to that observed in experiments and is accounted for in an explicit way as initial conditions of a dynamic boundary-value problem. The latter is stated in terms of plane strain developing in microstructure subjected to tension and is solved numerically by the finite-difference method. Elastic-plastic constitutive models were built to describe the experimental mechanical response both of the substrate and of the modified layer. Plastic strain localization is found to depend on the grain yield strength.</span>2016-12-08T00:00:00+01:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2333BIOSIMILAR ARTIFICIAL KNEE FOR TRANSFEMORAL PROSTHESES AND EXOSKELETONS2017-10-15T22:20:41+02:00Aleksandr Poliakova.m.poljakov@sevsu.ruVladimir Pakhaliukvpakhaliuk@gmail.comNikolay Lozinskiynlozinskiy@inbox.ruMarina Kolesovamarishaclass@mail.ruPavel Bugayovpasha_ba@mail.ruPetro Shtankomech@zntu.edu.ua<p><span lang="EN-US"><span style="font-family: Times New Roman; font-size: small;">Artificial knees play an important role in transfemoral prostheses, lower extremity exoskeletons and walking robots. Their designs must provide natural kinematics, high strength and stiffness required in the stance phase of gait. Additionally, modern artificial knee is the principal module by means of which the prosthesis control is performed. This paper presents a prototype of an artificial polycentric knee, designed on the basis of the hinge mechanism with cross links. In order to increase strength and stiffness, the elements of the joint have curved supporting surfaces formed in the shape of centroids in relative motion of links of the hinge mechanism. Such construction is a mechanical system with redundant links but it allows for providing desirable characteristics of the artificial knee. Synthesis of the hinge mechanism is made by a method of systematic study of the parameter space, uniformly distributed in a finite dimensional cube. Stiffness of bearing surfaces elements of knee was determined by solving the contact problem with slippage of surfaces relative to each other.</span></span></p>2016-12-08T00:00:00+01:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2328THE BOUNDARY ELEMENT METHOD FOR VISCOELASTIC MATERIAL APPLIED TO THE OBLIQUE IMPACT OF SPHERES2017-10-15T22:20:41+02:00Stephan Kusches.kusche@tu-berlin.deThe Boundary Element Method (BEM) for elastic materials is extended to deal with viscoelastic media. This is obtained by making use of a similar form of the fundamental solution for both the materials. Some considerations are attributed to the difference of the normal and the tangential contact problem. Both normal and tangential problems are furthermore assumed to be decoupled. Then the oblique impact of hard spheres with an incompressible viscoelastic half-space (linear standard-model) is studied. By assuming stick conditions during impact, one obtains the dependence of the two coefficients of restitution as functions of two input parameters. This result is expressed in an elegant and compact form of the fitting function.2016-12-08T00:00:00+01:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2369CRITICAL VELOCITY OF CONTROLLABILITY OF SLIDING FRICTION BY NORMAL OSCILLATIONS IN VISCOELASTIC CONTACTS2017-10-15T22:20:41+02:00Mikhail Popovmpopov@fastmail.fm<p style="margin-left: 0.3in; margin-right: 0.3in; font-weight: normal;"><span style="font-size: small;">Sliding friction can be reduced substantially by applying ultrasonic vibration in the sliding plane or in the normal direction. This effect is well known and used in many applications ranging from press forming to ultrasonic actuators. One of the characteristics of the phenomenon is that, at a given frequency and amplitude of oscillation, the observed friction reduction diminishes with increasing sliding velocity. Beyond a certain critical sliding velocity, there is no longer any difference between the coefficients of friction with or without vibration. This critical velocity depends on material and kinematic parameters and is a key characteristic that must be accounted for by any theory of influence of vibration on friction. Recently, the critical sliding velocity has been interpreted as the transition point from periodic stick-slip to pure sliding and was calculated for purely elastic contacts under uniform sliding with periodic normal loading. Here we perform a similar analysis of the critical velocity in viscoelastic contacts using a Kelvin material to describe viscoelasticity. A closed-form solution is presented, which contains previously reported results as special cases. This paves the way for more detailed studies of active control of friction in viscoelastic systems, a previously neglected topic with possible applications in elastomer technology and in medicine.</span></p>2016-12-08T00:00:00+01:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/2345METHOD OF DIMENSIONALITY REDUCTION IN CONTACT MECHANICS AND FRICTION: A USER'S HANDBOOK. II. POWER-LAW GRADED MATERIALS2017-10-15T22:20:41+02:00Markus Hessmarkus.hess@tu-berlin.deValentin L. Popovv.popov@tu-berlin.deUntil recently, the only way of solving contact problems was to applythree-dimensional contact theories. However, this presupposes higher mathematical and numerical knowledge, which usually only research groups possess. This has changed drastically with the development of the method of dimensionality reduction (MDR), which allows every practically oriented engineer an access to the solution of contact problems. The simple and contact-type dependent rules are summarized in the first part of the user manual; they require contacts between elastically homogeneous materials. The present paper forms the second part of the user handbook and is dedicated to the solution of contact problems between power-law graded materials. All the MDR-rules are listed with which normal, tangential and adhesive contacts between such high-performance materials can be calculated in a simple manner.2016-12-08T00:00:00+01:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/92SPLITTING THE TOTAL EXERGY DESTRUCTION INTO THE ENDOGENOUS AND EXOGENOUS PARTS OF THE THERMAL PROCESSES IN A REAL INDUSTRIAL PLANT2017-10-15T22:20:41+02:00Goran Vučkovićvucko@masfak.ni.ac.rsMića Vukićmicav@masfak.ni.ac.rsMirko Stojiljkovićmirko.stojiljkovic@gmail.comMiloš Simonovićsmilos@masfak.ni.ac.rsThe total exergy destruction occurring in a component is not only due to the component itself (endogenous exergy destruction) but is also caused by the inefficiencies of the remaining system components (exogenous exergy destruction). Hence care must be taken in using the total exergy destruction of a component for making decisions to optimize the overall energy system. In this paper, a complex industrial plant is analyzed by splitting the component’s exergy destruction into its endogenous part (the part resulting totally from the component’s irreversibilities) and its exogenous part (resulting from the irreversibilities of the other components within the system). It is observed that the steam generator has the dominant effect. From the total exergy destruction in the steam generator, 1,097.63 kW or 96.95% come from internal irreversibilities in the component, while the influence of other components on the loss of useful work in the steam generator is only 3.05%.2016-08-02T00:00:00+02:00Copyright (c) 2016 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1170CAD/CAM DESIGN AND GENETIC OPTIMIZATION OF FEEDERS FOR SAND CASTING PROCESS2017-10-15T22:20:41+02:00Nedeljko Dučićnedeljko.ducic@ftn.kg.ac.rsŽarko Ćojbašićzcojba@ni.ac.rsRadomir Radišaradomir.radisa@li.rsRadomir Slavkovićradomir.slavkovic@ftn.kg.ac.rsIvan Milićevićivan.milicevic@ftn.kg.ac.rsThe paper proposes methodology of feeder design and optimization for sand casting process. Casting part is a part of excavator buckets, i.e. holder of the cutting tooth. Process of design and optimization is based on the application of the rules, which are the result of many years of work researchers in the field of metal casting. Computer Aided Design (CAD) is used as a methodology in the design of feeders. Genetic Algorithm (GA) as an artificial intelligence technique is used in the optimization process of the feeder geometry. Computer Aided Manufacturing (CAM) is used as methodology that involves numerical simulation of the casting process. Numerical simulation is used to verify the validity of the optimized geometry of the feeding system.2016-08-02T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1292INSTABILITY OF THE RAYLEIGH-BENARD CONVECTION FOR INCLINED LOWER WALL WITH TEMPERATURE VARIATION2017-10-15T22:20:41+02:00Sadoon Ayedsadun_kad@yahoo.comGradimir Ilićgradei@masfak.ni.ac.rsPredrag Živkovićpzivkovic@masfak.ni.ac.rsMića Vukićmicav@masfak.ni.ac.rsMladen Tomićtomicmladen@yahoo.comThis paper deals with an analysis of a two-dimensional viscous fluid flow between the two parallel plates inclined with respect to the horizontal plane, where the lower plate is heated and the upper one is cooled. The temperature difference between the plates is gradually increased during a certain time period after which it is temporarily constant. The temperature distribution on the lower plate is not constant in x-direction, there is a longitudinal sinusoidal temperature variation imposed on the mean temperature. We have investigated the wave number and amplitude influence of this variation on the subcritical stability and the onset of the Rayleigh-Bénard convective cells, by direct numerical simulation of 2D Navier-Stokes and energy equation.2016-08-02T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1577SOFTWARE TOOL FOR LASER CUTTING PROCESS CONTROL – SOLVING REAL INDUSTRIAL CASE STUDIES2017-10-15T22:20:42+02:00Miloš Madićmadic@masfak.ni.ac.rsMarko Kovačevićmarkko.marce@gmail.comMiroslav Radovanovićmirado@masfak.ni.ac.rsVladislav Blagojevićvlada@masfak.ni.ac.rs<span style="font-family: 'Times New Roman','serif'; font-size: 10pt; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">Laser cutting is one of the leading non-conventional machining technologies with a wide spectrum of application in modern industry. It order to exploit a number of advantages that this technology offers for contour cutting of materials, it is necessary to carefully select laser cutting conditions for each given workpiece material, thickness and desired cut qualities. In other words, there is a need for process control of laser cutting. After a comprehensive analysis of the main laser cutting parameters and process performance characteristics, the application of the developed software tool “BRUTOMIZER” for off-line control of CO<sub>2</sub> laser cutting process of three different workpiece materials (mild steel, stainless steel and aluminum) is illustrated. Advantages and abilities of the developed software tool are also illustrated.<br /></span>2016-08-02T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1319ADAPTIVE NEURO-FUZZY COMPUTING TECHNIQUE FOR PRECIPITATION ESTIMATION2017-10-15T22:20:42+02:00Dalibor Petkovićdalibortc@gmail.comMilan Gocićmgocic@yahoo.comShahaboddin Shamshirbandshamshirband1396@gmail.com<p><em></em>The paper investigates the accuracy of an adaptive neuro-fuzzy computing technique in precipitation estimation. The monthly precipitation data from 29 synoptic stations in Serbia during 1946-2012 are used as case studies. Even though a number of mathematical functions have been proposed for modeling the precipitation estimation, these models still suffer from the disadvantages such as their being very demanding in terms of calculation time. Artificial neural network (ANN) can be used as an alternative to the analytical approach since it offers advantages such as no required knowledge of internal system parameters, compact solution for multi-variable problems and fast calculation. Due to its being a crucial problem, this paper presents a process constructed so as to simulate precipitation with an adaptive neuro-fuzzy inference (ANFIS) method. ANFIS is a specific type of the ANN family and shows very good learning and prediction capabilities, which makes it an efficient tool for dealing with encountered uncertainties in any system such as precipitation. Neural network in ANFIS adjusts parameters of membership function in the fuzzy logic of the fuzzy inference system (FIS). This intelligent algorithm is implemented using Matlab/Simulink and the performances are investigated. The simulation results presented in this paper show the effectiveness of the developed method.</p>2016-08-02T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1617AN EFFICIENT CO-ROTATIONAL FEM FORMULATION USING A PROJECTOR MATRIX2017-10-15T22:20:42+02:00Viet Anh Nguyenvietanh.nguyen@siemens.comManfred Zehnmanfred.zehn@tu-berlin.deDragan Marinkovićdragan.marinkovic@tu-berlin.de<p style="margin: 0cm 21.25pt 0pt;"><span lang="EN-US"><span style="font-family: Times New Roman; font-size: small;">Co-rotational finite element (FE) formulations can be seen as a very efficient approach to resolving geometrically nonlinear problems in the field of structural mechanics. A number of co-rotational FE formulations have been well documented for shell and beam structures in the available literature. The purpose of this paper is to present a co-rotational FEM formulation for fast and highly efficient computation of large three-dimensional elastic deformations. On the one hand, the approach aims at a simple way of separating the element rigid-body rotation and the elastic deformational part by means of the polar decomposition of deformation gradient. On the other hand, a consistent linearization is introduced to derive the internal force vector and the tangent stiffness matrix based on the total Lagrangian formulation. It results in a non-linear projector matrix. In this way, it ensures the force equilibrium of each element and enables a relatively straightforward upgrade of the finite elements for linear analysis to the finite elements for geometrically non-linear analysis. In this work, a simple 4-node tetrahedral element is used. To demonstrate the efficiency and accuracy of the proposed formulation, nonlinear results from ABAQUS are used as a reference.</span></span></p>2016-08-02T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1634REDUCTION OF RESIDUAL SHEAR STRESS IN THE LOADED CONTACT USING FRICTION HYSTERESIS2017-10-15T22:20:42+02:00Adrian Kraftadrian.kraft@posteo.deRoman Pohrtroman.pohrt@tu-berlin.de<p class="Abstract">We investigate the tangential contact problem of a spherical indenter at constant normal force. When the indenter is subjected to tangential movement, frictional shear stresses arise at the interface and do not vanish when it is moved backwards. We study the evolution of shear stress when the indenter is moved back and forth at falling amplitude. The method of dimensionality reduction (MDR) is employed for obtaining the distribution of stick and slip zones as well as external forces and the final stress distribution. We find that the shear stress decreases. For the special case of linearly falling amplitude of the movement, we observe uniform peaks in the shear stress. The absolute value of the shear stress peaks is reduced best for a high number of back-and-forth-movements with slowly decreasing amplitude.</p>2016-08-02T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1662THE PATH TOWARDS ACHIEVING A LEAN SIX SIGMA COMPANY USING THE EXAMPLE OF THE SHINWON COMPANY IN SERBIA2017-10-15T22:20:42+02:00Srđan Mladenovićmaki@masfak.ni.ac.rsPeđa Milosavljevićpedja@masfak.ni.ac.rsNevena Milojevićnevenaja@yahoo.comDragan Pavlovićdraganpavlovic10369@gmail.comMilena Todorovićmilenatod1@yahoo.comIn the last twenty years, many companies have realized that the demands of the global market, including more demanding and receptive customers, have set new standards for production flexibility. Gradual reduction of mass production, characteristic of a large number of companies, has opened space for the introduction of a new system which focuses exclusively on the customer. The customer-oriented system was created with the idea that process optimization would lead to the production of a relatively cheap product, delivered on time and with the best possible quality. Such a system is achieved by applying the Lean Six Sigma concept. The aim of this paper is to identify all of the defects that occur as losses and complicate the process of production in order to achieve the Lean Six Sigma level in the Shinwon Company. The original data from the Shinwon company were identified, collected and analyzed, using the methods and tools of the Lean Six Sigma concept (Process Mapping, 5S audit, Pareto diagram, Ishikawa diagram, Seven basic wastes and SPC analysis), in order to present the effectiveness of the quality management system and to evaluate the possibility of its continuous improvement.2016-08-02T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1750BROWNIAN HEAT TRANSFER ENHANCEMENT IN THE TURBULENT REGIME2017-10-15T22:20:42+02:00Suresh Chandrasekharsur.chandrasekhar@gmail.comVaarin Majumdar Sharmadummy1@yahoo.com<p class="Abstract">The paper presents convection heat transfer of a turbulent flow Al2O3/water nanofluid in a circular duct. The duct is a under constant and uniform heat flux. The paper computationally investigates the system’s thermal behavior in a wide range of Reynolds number and also volume concentration up to 6%. To obtain the nanofluid thermophysical properties, the Hamilton-Crosser model along with the Brownian motion effect are utilized. Then the thermal performance of the system with the nanofluid is compared to the conventional systems which use water as the working fluid. The results indicate that the use of nanofluid of 6% improves the heat transfer rate up to 36.8% with respect to pure water. Therefore, using the Al2O3/water nanofluid instead of water can be a great choice when better heat transfer is needed.</p>2016-08-02T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1854RELIABLE ROBUST CONTROLLER FOR HALF-CAR ACTIVE SUSPENSION SYSTEMS BASED ON HUMAN-BODY DYNAMICS2017-10-15T22:20:42+02:00Mohammad Gudarzimohammad.gudarzi@gmail.comThe paper investigates a non-fragile robust control strategy for a half-car active suspension system considering human-body dynamics. A 4-DoF uncertain vibration model of the driver’s body is combined with the car’s model in order to make the controller design procedure more accurate. The desired controller is obtained by solving a linear matrix inequality formulation. Then the performance of the active suspension system with the designed controller is compared to the passive one in both frequency and time domain simulations. Finally, the effect of the controller gain variations on the closed-loop system performance is investigated numerically.2016-08-02T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1637MODELS FOR INTRALAMINAR DAMAGE AND FAILURE OF FIBER COMPOSITES - A REVIEW2017-10-15T22:20:43+02:00Klaus Rohwerklaus.rohwer@dlr.de<p>In order to fully exploit the potential of structures made from fiber composites, designers need to know how damage occurs and develops and under what conditions the structure finally fails. Anisotropy and inhomogeneity cause a rather complex process of damage development which may be one reason for an exceptionally large number of existing models. This paper intends to provide an overview over those models and give some hints about current developments. As such it is an updated version of a recent publication [1]. The survey is limited to laminates from unidirectional layers out of straight continuous fiber polymer composites under quasi-static loading. Furthermore, focus is laid on intralaminar damage.<br />Many failure models smear out the inhomogeneity between fibers and the matrix. Simply limiting each stress component separately can lead to surprisingly good results as documented in the first World-Wide Failure Exercise. Interpolation criteria consider mutual influence of normal and shear stresses, predominantly through a quadratic failure condition. Traditionally one distinguishes between interpolation criteria and physically based ones. As an important physical effect the difference between fiber failure and inter-fiber failure is considered. Furthermore, stress invariants are taken as a basis, increased shear strength under compression is accounted for, and characteristic failure modes are captured. Fibers and the matrix material are characterized by a large disparity in stiffness and strength. Micromechanical models consider this inhomogeneity but suffer from the difficulty to determine relevant material properties. Compressive strength in fiber direction has attracted special attention. However, the role of kink band formation, which is observed in the failure process, seems to be not yet fully understood.<br />In summary it must be concluded that despite the tremendous effort which has been put into the model development the damage and failure simulation of fiber composites are not in a fully satisfying state. That is partly due to lack of accurate and reliable test results.</p><p> </p>2016-04-01T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/711AN ADVANCED COARSE-FINE SEARCH APPROACH FOR DIGITAL IMAGE CORRELATION APPLICATIONS2017-10-15T22:20:42+02:00Samo Simončičsamo.simoncic@fs.uni-lj.siMelita Kompolšekmelita.kompolsek@gmail.comPrimož Podržajprimoz.podrzaj@fs.uni-lj.siThe paper presents a newly developed fine search algorithm used in the application of digital correlation. In order to evaluate its performance a special purpose application was developed using C# programming language. The algorithm was then tested on a pre-prepared set of the computer generated speckled images. It turned out to be much faster than the conventional fine search algorithm. Consequently, it is a major step forward in a never ending quest for a fast digital correlation execution with sub pixel accuracy.<!--?xml:namespace prefix = "o" ns = "urn:schemas-microsoft-com:office:office" /-->2016-04-01T00:00:00+02:00Copyright (c) 2016 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1210EXPERIMENTAL FORCED SOLAR THIN LAYER GINGER DRYING2017-10-15T22:20:43+02:00Mahesh Kumarmk_shandilya@yahoo.comIn this research paper, the convective and the evaporative heat transfer coefficients of ginger (zingiber officinale) drying in an indirect solar cabinet dryer under the induced forced convection mode is presented. Experiments were conducted during the month of March 2015 under the climatic conditions of Hisar, India (29°5’5”N latitude and 75°45’55”E longitude). The experimental data obtained for solar drying of a constant ginger mass of 150 g has been used to determine constants ‘C’ and ‘n’ in the Nusselt number expression using linear regression analysis; consequently, the convective and the evaporative heat transfer coefficients have been evaluated. The average value of constants ‘C’ and ‘n’ were evaluated as 0.999 and 0.318, respectively. The average values of the convective and the evaporative heat transfer coefficients were found to be 3.95 W/m2 °C and 160.47 W/m2 °C, respectively, for the given mass samples of ginger. The average collector efficiency was observed to be 14.5%. The experimental error in terms of percentage uncertainty was found to be 20.87%.2016-04-01T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1332BENDING VIBRATION AND STABILITY OF A MULTIPLE-NANOBEAM SYSTEM INFLUENCED BY TEMPERATURE CHANGE2017-10-15T22:20:43+02:00Danilo Karličićdanilozmaj@gmail.comSanja Ožvatsanjao@uns.ac.rsMilan Cajićcaja84@gmail.comPredrag Kozićkozicp@yahoo.comRatko Pavlovićratko@masfak.ni.ac.rsIn this study, we analyzed the bending vibration and stability of a multiple-nanobeam system (MNBS) coupled in elastic medium and influenced by temperature change and compressive axial load. The MNBS is modeled as the system consisting of a set of m identical and simply supported nanobeams mutually connected by Winkler’s type elastic layers. According to the Euler - Bernoulli beam and nonlocal thermo-elasticity theory, the system of m coupled partial differential equations is derived and solved by means of the method of separation of variables as well as the trigonometric one. Analytical solutions for natural frequencies and critical buckling loads of elastic MNBS are obtained. The effects of nonlocal parameter, temperature change and the number of nanobeams on the natural frequencies and the buckling loads are investigated through numerical examples. Thus, this work can represent a starting point to examine dynamical behavior and design of complex nanobeam structures, nanocomposites and nanodevices under the influence of various physical fields.2016-04-01T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1364A STUDY OF THIN FILM LUBRICATION AT NANOSCALE FOR A FERROFLUID BASED INFINITELY LONG ROUGH POROUS SLIDER BEARING2017-10-15T22:20:43+02:00Jimit R. Patelpatel.jimitphdmarch2013@gmail.comGunamani Deherigm.dehri@rediffmail.comThe study aims at analyzing the performance of a ferrofluid-based infinitely long rough porous slider bearing which makes use of thin film lubrication at nanoscale. The stochastic model of Christensen and Tonder has been employed to analyze the effect of surface roughness while the Neuringer-Rosensweig’s model has been adopted to study the magnetization effect. The pressure distribution in the bearing system has been obtained by solving the associated stochastically averaged Reynolds type equation. The results indicate that although the transverse roughness is supposed to affect the bearing system adversely, the situation remains fairly better in the case of thin film lubrication at nanoscale. In fact, the consideration of thin film lubrication at nanoscale results in an all round improved performance, even for lower strength of the magnetic intensity. However, the couple stress adds a little more to this positive effect.2016-04-01T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1379SOLAR VACUUM TUBE INTEGRATED SEAWATER DISTILLATION - AN EXPERIMENTAL STUDY2017-10-15T22:20:43+02:00Selcuk Selimliselcukselimli@karabuk.edu.trZiyaddin Receblizrecebli@karabuk.edu.trSemra Ulkersmrulkr@uludag.edu.trThe subject of this study is the seawater distillation process enhancement through integration of the solar vacuum tube into the system. Positive effects on the rate of distillated freshwater achieved by means of the enhanced system have been investigated experimentally. Experiments were done in the Turkish city of Samsun in the Black Sea region. A distillation pond setup having the volume of 0.015m3 and a water surface area of 0.24m2 was constructed. The distillation pond is covered with a condensation glass and also equipped with a 0.15m solar vacuum tube that is inclined at an angle of 30o to the ground, a feed water tank connected with a ball cock, and distillated fresh water tank. Experimental results have shown that the rate of distilled fresh water was enhanced for about 62.5% by integrating the solar vacuum tube and the natural distillation pond. Isolation of the condensation glass not only prevents the light transmission to the pond but also heat loss from the pond; hence the rate of the distillated fresh water is increased for about 137.5% due to the natural distillation.2016-04-01T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1521LIMITING PROFILE OF AXISYMMETRIC INDENTER DUE TO THE INITIALLY DISPLACED DUAL-MOTION FRETTING WEAR2017-10-15T22:20:43+02:00Qiang Liqiang.li@tu-berlin.deRecently the final worn shape of elastic indenters due to fretting wear was analytically solved using the method of dimensionality reduction. In this paper we extend this model to dual-motion fretting wear and take into account that the indenter is initially pressed with constant indentation depth and moved horizontally with constant displacement. Two key parameters, the maximal indentation depth during oscillation and the stick area radius in the final state as well as the liming shape of indenter are analytically calculated. It is shown that the oscillation amplitudes and the initially indented or moved displacements have an influence on the final shaking-down shape.2016-04-01T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1629MU-SYNTHESIS BASED ACTIVE ROBUST VIBRATION CONTROL OF AN MRI INLET2017-10-15T22:20:43+02:00Atta Oveisiatta.oveisi@gmail.comTamara Nestorovićtamara.nestorovic@rub.de<p class="Abstract">In this paper, a robust control technique based on μ-synthesis is employed in order to investigate the vibration control of a funnel-shaped structure that is used as the inlet of a magnetic resonance imaging (MRI) device. MRI devices are widely subjected to the vibration of the magnetic gradient coil which then propagates to acoustic noise and leads to a series of clinical and mechanical problems. In order to address this issue and as a part of noise cancellation study in MRI devices, distributed piezo-transducers are bounded on the top surface of the funnel as functional sensor/actuator modules. Then, a reduced order linear time-invariant (LTI) model of the piezolaminated structure in the state-space representation is estimated by means of a predictive error minimization (PEM) algorithm as a subspace identification method based on the trust-region-reflective technique. The reduced order model is expanded by the introduction of appropriate frequency-dependent weighting functions that address the unmodeled dynamics and the augmented multiplicative modeling uncertainties of the system. Then, the standard D-K iteration algorithm as an output-feedback control method is used based on the nominal model with the subordinate uncertainty elements from the previous step. Finally, the proposed control system implemented experimentally on the real structure is to evaluate the robust vibration attenuation performance of the closed-loop system.</p>2016-04-01T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1689MODAL TRIGGERED NONLINEARITIES FOR DAMAGE LOCALIZATION IN THIN WALLED FRC STRUCTURES – A NUMERICAL STUDY2017-10-15T22:20:43+02:00Tobias Rademachertobias.kaempf@tu-berlin.deManfred Zehnmanfred.zehn@tu-berlin.de<p>This paper presents a novel method for detecting locations of damages in thin walled structural components made of fiber reinforced composites (FRC). Therefore, the change of harmonic distortion, which is found by current research to be very sensitive to delamination, under resonant excitation will be derived from FEM-simulation. Based on the linear modal description of the undamaged structure and the damage-induced nonlinearities represented by a nonlinear measure, two spatial damage indexes have been formulated.<br />The main advantage of this novel approach is that the information about the defect is represented mainly by changes in the modal harmonic distortion (MHD), which just needs to be measured in one (or few) structural points. The spatial resolution is given by the pairwise coupling of the MHD with the corresponding mode shapes.</p>2016-04-01T00:00:00+02:00Copyright (c) 2016 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1429FOREWORD2017-10-15T22:20:45+02:00Miroslav Trajanovićtraja@masfak.ni.ac.rsOsiris Canciglieri Jrosiris.canciglieri@pucpr.br<p>Foreword to the thematic issue entitled:</p><p><em>BIOMEDICAL ENGINEERING - ONE OF THE GREATEST ENGINEERING CHALLENGES</em></p>2015-12-09T00:00:00+01:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/456ONTOLOGICAL FRAMEWORK FOR KNOWLEDGE MANAGEMENT IN ORTHOPEDIC SURGERY2017-10-15T22:20:44+02:00Milan Zdravkovićmilan.zdravkovic@gmail.comMiroslav Trajanovićtraja@masfak.ni.ac.rsDragan Pavlovićdraganpavlovic10369@gmail.comEfficiency and effectiveness of orthopedic surgery can be achieved by enabling proper decision-making in a shortest period of time, based on complete and updated information on the status, type of fracture and fixators used for a particular fracture. In this way, the risk of possible complications caused by a late intervention can be reduced. In such circumstances, there exist critical needs for an effective and efficient knowledge management approach where different domain models are combined and formally interrelated, so that the decisions are based on the consistent and complete information. In this paper, ontologies are used to propose a framework for implementing such an approach in the domain of orthopedic surgery. The framework combines formal models of the generic products and supply chains for their manufacturing and delivery, anatomical elements, e.g. bones, types of their fractures and fixators – the medical products which are used in the fracture treatments. Then the possible uses of this framework for the purpose of knowledge management in orthopedic surgery are discussed in the context of the assumptions of development of Next Generation Enterprise Information Systems.2015-12-09T00:00:00+01:00Copyright (c) 2015 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/685APPLICABILITY ANALYSIS OF ADDITIVE MANUFACTURING PROCESSES IN THE FABRICATION OF ANATOMICALLY SHAPED LATTICE SCAFFOLDS2017-10-15T22:20:44+02:00Jelena Milovanovićjeka.milovanovic@gmail.comMiloš Stojkovićmiloss@masfak.ni.ac.rsMiroslav Trajanovićmiroslav.trajanovic@masfak.ni.ac.rs<p>Manufacturing of anatomically shaped scaffolds for bonе tissue recovery as well as other similar anatomically shaped implants represents a major challenge for modern manufacturing technologies. The complexity of anatomically shaped lattice scaffolds for bone tissue recovery requires involvement of so-called additive manufacturing processes.</p><p>This paper brings out the criterial matrix for the assessment of additive manufacturing processes applicability in the case of bone tissue scaffold manufacturing. Moreover, this criterial<strong> </strong>matrix serves as the basis for developing Calculator for the generic assessment of additive manufacturing processes applicability. In this very particular case the subject of consideration is an anatomically shaped lattice scaffold intended for the recovery of large trauma located in the upper part of proximal diaphyseal of rabbit tibia. The criterial matrix and the Calculator defined for this case prove themselves as generic tools for comparative analyses of applicability of different additive manufacturing processes. Furthermore, these tools can help identifying the most demanded features of some future additive manufacturing process that has to be developed for the specific case.</p>2015-12-09T00:00:00+01:00Copyright (c) 2015 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/677WHAT CAN WE LEARN FROM THE “WATER BEARS” FOR THE ADHESION SYSTEMS USING IN SPACE APPLICATIONS?2017-10-15T22:20:44+02:00Alexander E. Filippovfilippov_ae@yahoo.comStanislav N. Gorbsgorb@zoologie.uni-kiel.deValentin L. Popovv.popov@tu-berlin.deRecent progress in space research and in particular appearance of complex movable constructions with a number of components exposed to the extreme conditions of open space causes a strong demand for development of new tribological and adhesion systems which are able to resist such conditions. In the last few years, many engineering solutions in the field of tribology and adhesion have been found based on “biomimetics approach” that is searching for ideas originally created by living nature and optimized during billions of years of natural selection. Surprisingly some of the living creatures are found to be optimized even for survival for a long time in the conditions of open space. Such ability is very promising from the point of view of development of new adhesives for future space applications. In this paper we discuss what we can learn in this context from the so-called “water bears” (tardigrades) in a combination with some other features, already adopted to reversible technical adhesives from other animals, such as insects and Gecko lizards.2015-12-09T00:00:00+01:00Copyright (c) 2015 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/942FINITE-ELEMENT MODELLING OF THE TYMPANIC MEMBRANE RETRACTION POCKET UNDER NEGATIVE PRESSURE IN THE TYMPANIC CAVITY2017-10-15T22:20:44+02:00Gennadi I. Mikhasevmikhasev@bsu.bySergei M. Bosiakovbosiakov@bsu.byLyudmila G. Petrovarnpc@lor.byMarina M. Maisyukmerylmmm@mail.ruThe finite-element calculation of the static stress-strain state of the middle ear was made in this paper. The malleus, incus and stapes models were constructed on the basis of tomographic data. The tympanic membrane model was obtained using the equations of elliptic hyperboloids. The tympanic membrane consists of the pars tensa and pars flaccida, which have different thicknesses and elasticity moduli. Absolute deformations of the tympanic membrane were defined at different values of negative pressure in the tympanic cavity. The critical values of elastic modulus for the pars tensa posterosuperior quadrant were found for the point at which the tympanic membrane touches the auditory ossicles. Obtained results can be used to predict the thickness of a cartilaginous graft which is overlaid on the posterosuperior quadrant of the pars tensa in order to eliminate the retraction pocket.2015-12-09T00:00:00+01:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1003TOWARD AN INTEGRATED INFORMATION SYSTEM FOR THE DESIGN, MANUFACTURING AND APPLICATION OF CUSTOMIZED IMPLANTS2017-10-15T22:20:44+02:00Dragan Mišićmisicdr@gmail.comMiodrag Manićmiodrag.manich@gmail.comNikola Vitkovićvitko@masfak.ni.ac.rsNikola Korunovićkorunovic.nikola@gmail.comThe adjustment of products to the needs of customers has been present in various industries for many years. Personalized medicine is a field that has been rapidly developing recently. This kind of medical help mainly implies the use of medications which are adjusted to each patient individually. In this paper, we describe an information system which manages the process of designing and manufacturing personalized products in the area of orthopaedics. The system output comprises patient-adjusted orthopaedic implants. In addition to the process management, the information system ought to enable the process to be adjusted to unexpected situations which may occur in different stages of designing and manufacturing. The information system should also assist doctors and engineers in the decision making process. This aid is realized in the form of the expert system which provides doctors and engineers with advice about defining an appropriate treatment for the patient.2015-12-09T00:00:00+01:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1133REVERSE ENGINEERING OF THE MITKOVIC TYPE INTERNAL FIXATOR FOR LATERAL TIBIAL PLATEAU2017-10-15T22:20:44+02:00Nikola Vitkovićnvitko@gmail.comMilan M. Mitkovićmilanmitkovic@hotmail.comMilorad B. Mitkovićmitkovic@gmail.comNikola Korunovićkorunovic.nikola@gmail.comDalibor Stevanovićdalibor.stevanovic85@gmail.comMarko Veselinovićveselinovic.marko.meng@gmail.comIn orthopaedic surgery it is very important to use proper fixation techniques in the treatment of various medical conditions, i.e. bone fractures or other traumas. If an internal fixation method, such as plating, is required, it is possible to use Dynamic Compression Plates (DCP) or Locking Compression Plates (LCP) and their variants. For DCP implants it is important to match the patient's bone shape with the most possible accuracy, so that the most frequent implant bending is applied in the surgery. For LCP implants it is not so important to match the patient’s bone shape, but additional locking screw holes are required. To improve the geometrical accuracy and anatomical correctness of the shape of DCP and to improve the LCP geometric definition, new geometrical modelling methods for the Mitkovic type internal fixator for Lateral Tibia Plateau are developed and presented in this research. The presented results are quite promising; it can be concluded that these methods can be applied to the creation of geometrical models of internal fixator customized for the given patient or optimized for a group of patients with required geometrical accuracy and morphological correctness.2015-12-09T00:00:00+01:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1371THE GAIT SIMULATOR FOR LOWER LIMB EXOPROSTHESES – OVERVIEW AND FIRST MEASUREMENTS FOR COMPARISON OF MICROPROCESSOR CONTROLLED KNEE JOINTS2017-10-15T22:20:45+02:00Julius Thielejulius.thiele@tu-berlin.deSimon Gallingersimon.gallinger@tu-berlin.dePeter Seufertpeter.seufert@tu-berlin.deMarc Kraftmarc.kraft@tu-berlin.deA test device for lower limb exoprostheses has been developed at the Department of Medical Engineering of the TU Berlin which is able to apply realistic loads to prostheses. Hence, the gait simulator meets the increasing demands on functional and fatigue testing of microprocessor controlled knee joints (MPK). An exemplary comparison of two MPK was performed to prove that known differences in the functional quality of the MPK can also be demonstrated in simulator tests. Significant differences between the MPK could be found. The MPK could not be tested in their full range of function though. To enable comprehensive functional and fatigue testing, the gait simulator has to be modified to achieve higher walking velocities and step lengths.2015-12-09T00:00:00+01:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1153DESIGN OF 3D MODEL OF CUSTOMIZED ANATOMICALLY ADJUSTED IMPLANTS2017-10-15T22:20:44+02:00Miodrag Manićmiodrag.manic@masfak.ni.ac.rsZoran Stamenkovićzoki2101984@gmail.comMilorad Mitkovićmitkovic@gmail.comMiloš Stojkovićmilos.stojkovich@gmail.comDuncan E.T. Shephardd.e.shepherd@bham.ac.ukDesign and manufacturing of customized implants is a field that has been rapidly developing in recent years. This paper presents an originally developed method for designing a 3D model of customized anatomically adjusted implants. The method is based upon a CT scan of a bone fracture. A CT scan is used to generate a 3D bone model and a fracture model. Using these scans, an indicated location for placing the implant is recognized and the design of a 3D model of customized implants is made. With this method it is possible to design volumetric implants used for replacing a part of the bone or a plate type for fixation of a bone part. The sides of the implants, this one lying on the bone, are fully aligned with the anatomical shape of the bone surface which neighbors the fracture. The given model is designed for implants production utilizing any method, and it is ideal for 3D printing of implants.2015-12-09T00:00:00+01:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1347AUTONOMOUS CT REPLACEMENT METHOD FOR THE SKULL PROSTHESIS MODELLING2017-10-15T22:20:44+02:00Marcelo Rudekmarcelo.rudek@pucpr.brYohan Boneski Gumielyohan_bg@hotmail.comOsiris Canciglieri Jrosiris.canciglieri@pucpr.brThe geometric modeling of prosthesis is a complex task from medical and engineering viewpoint. A method based on CT replacement is proposed in order to circumvent the related problems with the missing information to modeling. The method is based on digital image processing and swarm intelligence algorithm. In this approach, a missing region on the defective skull is represented by curvature descriptors. The main function of the descriptors is to simplify the skull’s contour geometry; and they are defined from the Cubic Bezier Curves using a meta-heuristic process for parameter’s estimation. The Artificial Bee Colony (ABC) optimization technique is applied in order to evaluate the best solution. The descriptors from a defective CT slice image are the searching parameters in medical image databases, and a similar image, i.e. with similar descriptors, can be retrieval and used to replace the defective slice. Thus, a prosthesis piece is automatically modeled with information extracted from distinct skulls with similar anatomical characteristics.2015-12-09T00:00:00+01:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1348A DATA-MINING BASED METHOD FOR THE GAIT PATTERN ANALYSIS2017-10-15T22:20:45+02:00Marcelo Rudekmarcelo.rudek@pucpr.brNicoli Mariá Silvanick_nicoli@hotmail.comJean-Paul Steinmetzjean-paul.steinmetz@zitha.luAndreas Jahnenandreas.jahnen@list.luThe paper presents a method developed for the gait classification based on the analysis of the trajectory of the pressure centres (CoP) extracted from the contact points of the feet with the ground during walking. The data acquirement is performed ba means of a walkway with embedded tactile sensors. The proposed method includes capturing procedures, standardization of data, creation of an organized repository (data warehouse), and development of a process mining. A graphical analysis is applied to looking at the footprint signature patterns. The aim is to obtain a visual interpretation of the grouping by situating it into the normal walking patterns or deviations associated with an individual way of walking. The method consists of data classification automation which divides them into healthy and non-healthy subjects in order to assist in rehabilitation treatments for the people with related mobility problems.2015-12-09T00:00:00+01:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1367EVIDENCE OF THE SEMI-SOLID FORMATION IN THE MEDICAL GRADE TI6AL4V ALLOY USING INDUCTION HEATING2017-10-15T22:20:45+02:00Carlos Roberto Fernandescarlosfernandes@igcb.org.brBeatriz Luci Fernandesbeatriz.fernandes@pucpr.brOne alternative for processing cost reduction with simultaneous improvement of the mechanical properties of the Medical Ti6Al4V alloy is to get its semi-solid feedstock with a non-dendritic microstructure for further processing. The purpose of the present work is to evaluate the possibility of obtaining a semi-solid Ti6Al4V alloy by heating it up from the room temperature to the range temperature between the lines <span style="text-decoration: underline;">solidus</span> and <span style="text-decoration: underline;">liquidus</span>, using induction heating. The Ti6Al4V billets underwent heat treatment and quenching for semi-solid formation using a designed device and specific time pulsed profile. The billet temperature reached 1630 <sup>o</sup>C, and after the cooling rate of 54 <sup>o</sup>C/s, some samples formed a globular phase characteristic of the semi-solid alloy. This study shows that it is possible to get a semi-solid microstructure of this alloy starting from its solid state.2015-12-09T00:00:00+01:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1395BONE HEALING IN MICE: DOES IT FOLLOW GENERIC MECHANO-REGULATION RULES?2017-10-15T22:20:45+02:00Edoardo Borgianiedoardo.borgiani@charite.deGeorg DudaGeorg.Duda@charite.deBettina WillieBettina.Willie@charite.deSara ChecaSara.Checa@charite.de<p class="Abstract">Mechanical signals are known to influence bone healing progression. Previous studies have postulated inter-species differences in the mechanical regulation of the bone healing process. The aim of this study is to investigate whether mechanical “rules” explaining tissue formation patterns during bone healing in rat can be translated to a mouse model of bone regeneration. We have used an established mechano-biological computer model that uses finite element techniques to determine the mechanical conditions within the healing region and an agent-based approach to simulate cellular activity. The computer model is set up to simulate the course of bone healing in a femoral osteotomy model stabilized with an external fixator. Computer model predictions are compared to corresponding histological data. Generic mechano-regulation “rules” able to explain bone healing progression in the rat are not able to describe tissue formation over the course of healing in the mouse. According to the differentiation theory proposed by Prendergast, mechanical stimuli within the healing region immediately post-surgery are determined to be favorable for cartilage and fibrous tissue formation. In contrast, in vivo histological data showed initial intramembraneous bone formation at the periosteal side. These results suggest that in mice, bone does not require as much stability as is required in rat to reach timely healing. This finding emphasizes the need to further investigate the species-specific mechano-biological regulation of bone regeneration.</p>2015-12-09T00:00:00+01:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/154THE EFFECT OF ENVIRONMENTAL INDICATORS TO THE WASTE TREATMENT SCENARIOS RANKING2017-10-15T22:20:45+02:00Biljana Milutinovićbimilutinovic@gmail.comGordana Stefanovićgoca@masfak.ni.ac.rsGoran Vučkovićgoran.vuckovic71@gmail.comMladen Tomićmladeninenad@gmail.comPetar Đekićdjekicpetar@yahoo.com<p class="Abstract">The selection of an appropriate waste treatment scenario is a complex problem in which a set of environmental, economic, and social criteria must be taken into account. Different waste treatment scenarios have different effects on the environment, which is expressed through a variety of environmental indicators. The main problem is to determine the indicators that clearly and fully express the most important influential factors. This paper presents a number of different environmental indicators and their influence on the waste treatment scenarios ranking. The study is carried out on the example of waste management in the city of Niš. Four scenarios are developed: the business as a usual scenario (meaning the landfilling of waste) and the three other scenarios with energy recovery and preservation of resources including composting organic waste with recycling inorganic waste, incineration of waste, and anaerobic digestion of waste. Four experiments were conducted in order to assess the influence of environmental indicators: the first experiment was done using four indicators, the second by using seven indicators, the third experiment by using nine indicators, and the fourth experiment by twelve indicators. The ranking of each scenario was performed on the basis of a multi-criteria analysis, the Analytic Hierarchy Process (AHP method). The obtained results have shown that the increasing number of environmental indicators has led to a change in the ranking of scenarios in terms of their impact on the environment. Namely, it is necessary to increase the number of environmental indicators to a number which will be sufficient to carry out the relevant waste treatment scenario ranking in terms of the impact on the environment.</p>2015-08-15T00:00:00+02:00Copyright (c) 2015 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/743EXPERIMENTAL AND NUMERICAL DETERMINATION OF THE WHEEL-RAIL ANGLE OF ATTACK2017-10-15T22:20:45+02:00Dragan Milkovićdmilkovic@mas.bg.ac.rsGoran Simićgsimic@mas.bg.ac.rsJovan Tanaskovićjtanaskovic@mas.bg.ac.rsŽivana Jakovljevićzjakovljevic@mas.bg.ac.rsVojkan Lučaninvlucanin@mas.bg.ac.rsAngle of attack is an important wheel-rail contact parameter. It serves for estimation of the rolling stock curving performance. Together with wheel-rail contact forces, angle of attack influences the wear index. This paper presents experimental on-track measurements of the angle of attack using a specially designed laser device installed on track. Experiments are performed on three types of rail vehicles: shunting locomotive series 631-301, motor unit 412-077 and trailing unit 416-077 of electromotor train 412/416. Experimental measurements are compared with multibody system (MBS) simulations using specialized computer package VAMPIRE Pro. We have found good agreement between the results obtained experimentally and by simulations. Using these data, we have also performed relative comparison of wear indices of the outer wheels of the leading wheelsets for each of the tested vehicles.2015-08-15T00:00:00+02:00Copyright (c) 2015 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/887APPLICATION OF SMART MOBILE PHONES IN VIBRATION MONITORING2017-10-15T22:20:46+02:00Ljubomir Vračarljubomir.vracar@gmail.comMiloš Milovančevićmilovancevic@masfak.ni.ac.rsPetra Karanikićpkaranikic@uniri.hrThe purpose of the research presented in this paper is the development of the smart mobile phone application for vibration monitoring of pumping aggregate, based on Microchip’s microcontroller (MC). Hardware used is based on Bluetooth connection between smart sensor and smart mobile phone. Software for acquisition and data analysis is optimized for imbedded application in smart sensors. Smart acceleration sensor in conjunction with Bluetooth connection to smart mobile phone creates one touch mobile vibration monitoring system. The authors have performed numerous measurements on a wide range of aggregates for establishing the operating functionality of the newly created system. The possibility of system application I rail vehicle vibration monitoring is also analyzed.2015-08-15T00:00:00+02:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/832PRECEDENT-FREE FAULT LOCALIZATION AND DIAGNOSIS FOR HIGH SPEED TRAIN DRIVE SYSTEMS2017-10-15T22:20:45+02:00Asad Ul Haqasadulhaq@utexas.eduDragan Djurdjanovićdragand@me.utexas.eduIn this paper, a framework for localization of sources of unprecedented faults in the drive train system of high speed trains is presented. The framework utilizes distributed anomaly detection, with anomaly detectors based on the recently introduced Growing Structure Multiple Model Systems (GSMMS) models. Physics based models of the drive system and its pertinent subsystems were derived and were calibrated using data collected over several actual trips on a high speed train. Simulation results demonstrate the ability to localize faults within various parts of the drive train system without the need for models of the underlying faults. In addition, traditional model based diagnosis was utilized for positive identification of faults, with signals emitted by the systems in the presence of those faults being available for modeling and subsequent recognition of faulty behavior.2015-08-15T00:00:00+02:00Copyright (c) 2015 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/844RAIL TRAFFIC VOLUME ESTIMATION BASED ON WORLD DEVELOPMENT INDICATORS2017-10-15T22:20:46+02:00Luka Lazarevićllazarevic@grf.bg.ac.rsMiloš Kovačevićmilos@grf.bg.ac.rsZdenka Popovićzdenka@grf.bg.ac.rsEuropean transport policy, defined in the White Paper, supports shift from road to rail and waterborne transport. The hypothesis of the paper is that changes in the economic environment influence rail traffic volume. Therefore, a model for prediction of rail traffic volume applied in different economic contexts could be a valuable tool for the transport planners. The model was built using common Machine Learning techniques that learn from the past experience. In the model preparation, world development indicators defined by the World Bank were used as input parameters.2015-08-15T00:00:00+02:00Copyright (c) 2015 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/991DETERMINATION OF FRICTION HEAT GENERATION IN WHEEL-RAIL CONTACT USING FEM2017-10-15T22:20:47+02:00Aleksandar Miltenovićamiltenovic@yahoo.comMilan Banićmilan.banic@outlook.comDušan Stamenkovićstamendu@gmail.comMiloš Miloševićmmilos@masfak.ni.ac.rsMiša Tomićmisa.tomic@masfak.ni.ac.rsThe modeling of the friction heat generation has become increasingly important in product design process including areas such as electronics, automotive, aerospace, railway (e. g. wheel and rail rolling contact, braking systems, and so on), medical industries, etc. Determination of generated friction heat in the contact of wheel and rail is important for understanding the damage mechanisms on these two bodies such as wear. This paper presents a method to determine the friction generated heat in contact of wheel and rail during normal operation using transient structural-thermal analysis in ANSYS software.2015-08-15T00:00:00+02:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1065APPLICATION OF THE METHOD OF DIMENSIONALITY REDUCTION TO CONTACTS UNDER NORMAL AND TORSIONAL LOADING2017-10-15T22:20:47+02:00Emanuel Willerte.willert@tu-berlin.deMarkus Hessmarkus.hess@tu-berlin.deValentin L. Popovv.popov@tu-berlin.de<p>Recently the method of dimensionality reduction (MDR) has been introduced to solve axisymmetric contact problems easily and exactly. The list of tasks that this method can deal with comprises normal, tangential, adhesive and rolling contacts with simply connected contact areas between elastic or viscoelastic bodies. Due to its simplicity and easy applicability the MDR provides the possibility of fast and comprehensive studies of contact problems in technological or biological systems, for example bearings, artificial hip joints, wheel-rail systems or others. Within the complicated three-dimensional contact theory those studies, in most cases, cannot be done without a tremendous mathematical or numerical effort.<br />In view of all this, the torsional contact problems have been disregarded until now, although it is known that torsion is a major reason of wear and possible failure of system components. Therefore, in the present paper, we extend the MDR to contacts of axisymmetric profiles under superimposed normal and torsional loading.</p>2015-08-15T00:00:00+02:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1074SOFTWARE TESTING OF THE RAIL VEHICLE DYNAMIC CHARACTERISTICS2017-10-15T22:20:47+02:00Sanjin Trohasanjin.troha@riteh.hrMiloš Milovančevićmilovancevic@masfak.ni.ac.rsAlireza Kuchakalireza.jk@mailbox.tu-berlin.de<p>The modern construction concept and the determination of the machine system characteristics anticipate CAD design. Creating model that will be tested using FEM and other methods for determining stress-strain is a very important part of rail vehicle construction. Applicative software package consists of linear and non–linear methods for the prediction of railway vehicle behavior and various methods of analysis have been assembled into a single coherent package in order to allow real problems in railway vehicle dynamics to be solved.</p>2015-08-15T00:00:00+02:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1080NON-LINEAR MATHEMATICAL MODELS IN THE THEORY OF EXPERIMENTAL DESIGN: APPLICATION IN THE MANUFACTURING PROCESSES2017-10-15T22:20:47+02:00Anđela Lazarevićandjela.lazarevic@gmail.comDragoljub Lazarevićdlazarevic@masfak.ni.ac.rsSince real processes usually are not linear, different non-linear mathematical models are usually applied for studying their behavior: high order polynomials, power, exponential and other functions. In this paper, the application of multiple power functions is presented, with and without interactions between the influential factors, in modelling various technological problems. The modeling results show that the proper mathematical model is selected, one that guarantees high accuracy in the entire experimental space. Furthermore, an important conclusion is reached, stating that interactions between the influential factors are not of importance in such mathematical models; thus they can be neglected. Therefore, it is shown that it is more practical to use the basic mathematical model (without interactions) than the expanded mathematical model (with interactions).2015-08-15T00:00:00+02:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1096ANALYSIS OF THE RESULTS OF THEORETICAL AND EXPERIMENTAL STUDIES OF FREIGHT WAGON FALS2017-10-15T22:20:47+02:00Svetoslav Slavchevdummy12345891@yahoo.comKalina Georgievadummy12345891@yahoo.comValeri Stoilovdummy12345891@yahoo.comSanel Purgićs_purgic@tu-sofia.bgA comparative analysis based on the results from strength-deformation analysis of wagon body, series Fals, and on the results from the real wagon test was made. Calculations were carried out in the Department of Railway Engineering at Technical University of Sofia and are based on the finite elements method. Two computational models of wagon design were developed. One of them consists of shell elements (triangular), and the second one of solid elements (tetrahedral). Experimental studies on real wagon were conducted at the National Transport Research Institute. It was found that the results obtained for the stresses are similar, which proves that the models are appropriate and they can help to solve a wide range of issues, for example those related to lightweight design of railway vehicles.2015-08-15T00:00:00+02:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/1088OPTICAL MODEL AND NUMERICAL SIMULATION OF THE NEW OFFSET TYPE PARABOLIC CONCENTRATOR WITH TWO TYPES OF SOLAR RECEIVERS2017-10-15T22:20:47+02:00Saša Pavlovićsaledoca@gmail.comDarko Vasiljevićdarko@ipb.ac.rsVelimir Stefanovićveljas@masfak.ni.ac.rsZoran Stamenkovićzoki2101984@gmail.comSadoon Ayedsadun_kad@yahoo.comThe paper presents a physical and mathematical model of the new offset type parabolic concentrator and a numerical procedure for predicting its optical performances. Also presented is the process of design and optical ray tracing analysis of a low cost solar concentrator for medium temperature applications. This study develops and applies a new mathematical model for estimating the intercept factor of the solar concentrator based on its geometrical and optical behavior. The solar concentrating system consists of three offset parabolic dish reflectors and a solar thermal absorber at the focus. Two types of absorbers are discussed. One is a flat plate circular absorber and the other a spiral smooth pipe absorber. The simulation results could serve as a useful reference for design and optimization of offset parabolic concentrators.2015-08-15T00:00:00+02:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/921FOREWORD2017-10-15T22:20:48+02:00Valentin L. Popovv.popov@tu-berlin.deSergey G. Psakhiesp@ms.tsc.ruAlexander G. ChernyavskyAlexander.Cherniavsky@rsce.ru<p align="center">Foreword to the thematic issue entitled:</p><p align="center"><em>TRIBOLOGY IN AEROSPACE APPLICATIONS – DAMPING, </em><em>WEA</em><em>R AND STRUCTURAL DYNAMICS IN AEROSPACE SYSTEMS</em><em></em></p><br /><em></em>2015-04-09T00:00:00+02:00Copyright (c) 2015 Facta Universitatis, Series: Mechanical Engineeringhttp://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/760NON-FRICTIONAL DAMPING IN THE CONTACT OF TWO FIBERS SUBJECT TO SMALL OSCILLATIONS2017-10-15T22:20:47+02:00Mikhail Popovmikhail.popov@tu-berlin.de<!-- p { margin-bottom: 0.08in; direction: ltr; color: rgb(0, 0, 0); text-align: justify; widows: 2; orphans: 2; }p.western { font-family: "Times New Roman",serif; font-size: 10pt; }p.cjk { font-family: "Calibri",sans-serif; font-size: 10pt; }p.ctl { font-family: "Times New Roman",serif; font-size: 11pt; }a:link { color: rgb(0, 0, 255); } --><p class="western" style="margin-bottom: 0in;">Structural damping is discussed for the contact of two fibers in a woven material. In the presence of both normal and tangential oscillations, structural (relaxation) damping takes place even with perfect sticking in the contact, where slip-related frictional damping disappears. For the case of an infinite coefficient of friction and small amplitudes a closed-form solution for energy lost during one oscillation cycle is obtained.</p>2015-04-09T00:00:00+02:00Copyright (c) 2015 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/763EXPERIMENTAL INVESTIGATION OF THE ADHESIVE CONTACT WITH ELASTOMERS: EFFECT OF SURFACE ROUGHNESS2017-10-15T22:20:47+02:00Lars Volllars.voll@tu-berlin.de<p>Adhesion between an elastomer and a steel indenter was studied experimentally and described with an analytical model. Cylindrical indenters having different roughness were brought into contact with an elastomer with various normal forces. After a “holding time”, the indenter was pulled with a constant velocity, which was the same in all experiments. We have studied the regime of relatively small initial normal loadings, large holding times and relatively large pulling velocities, so that the adhesive force did not depend on the holding time but did depend on the initially applied normal force and was approximately proportional to the pulling velocity. Under these conditions, we found that the adhesive force is inversely proportional to the roughness and proportional to the normal force. For the theoretical analysis, we used a previously published MDR-based model.</p>2015-04-09T00:00:00+02:00Copyright (c) 2015 http://casopisi.junis.ni.ac.rs/index.php/FUMechEng/article/view/751ANALYSIS OF IMPACT ON COMPOSITE STRUCTURES WITH THE METHOD OF DIMENSIONALITY REDUCTION2017-10-15T22:20:47+02:00Valentin L. Popovv.popov@tu-berlin.de<p class="Abstract">In the present paper, we discuss the impact of rigid profiles on continua with non-local criteria for plastic yield. For the important case of media whose hardness is inversely proportional to the indentation radius, we suggest a rigorous treatment based on the method of dimensionality reduction (MDR) and study the example of indentation by a conical profile.</p>2015-04-09T00:00:00+02:00Copyright (c) 2015