Journal Cover Facta Universitatis, Series : Mechanical Engineering
  [3 followers]  Follow
    
  This is an Open Access Journal Open Access journal
   ISSN (Print) 0354-2025 - ISSN (Online) 2335-0164
   Published by U of Niš Homepage  [11 journals]
  • FOREWORD

    • Authors: Vlastimir Nikolić, Dragan Marinković
      Abstract: Foreword to the issue dedicated to the SAUM 2016 conference.
      PubDate: 2017-08-02
      Issue No: Vol. 15, No. 2 (2017)
       
  • NOISE CONTROL OF VEHICLE DRIVE SYSTEMS

    • Authors: Ulrich Gabbert, Fabian Duvigneau, Stefan Ringwelski
      Pages: 183 - 200
      Abstract: The 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.

      PubDate: 2017-08-02
      Issue No: Vol. 15, No. 2 (2017)
       
  • ROBOT LEARNING OF OBJECT MANIPULATION TASK ACTIONS FROM HUMAN
           DEMONSTRATIONS

    • Authors: Maria Kyrarini, Muhammad Abdul Haseeb, Danijela Ristić-Durrant, Axel Gräser
      Pages: 217 - 229
      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.
      PubDate: 2017-08-02
      Issue No: Vol. 15, No. 2 (2017)
       
  • AUTOMOTIVE APPLICATIONS OF EVOLVING TAKAGI-SUGENO-KANG FUZZY MODELS

    • Authors: Radu-Emil Precup, Stefan Preitl, Claudia-Adina Bojan-Dragos, Mircea-Bogdan Radac, Alexandra-Iulia Szedlak-Stinean, Elena-Lorena Hedrea, Raul-Cristian Roman
      Pages: 231 - 244
      Abstract: This 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.
      PubDate: 2017-08-02
      Issue No: Vol. 15, No. 2 (2017)
       
  • DECOUPLING CONTROL OF TITO SYSTEM SUPPORTED BY DOMINANT POLE PLACEMENT
           METHOD

    • Authors: Novak N. Nedić, Saša Lj. Prodanović, Ljubiša M. Dubonjić
      Pages: 245 - 256
      Abstract: Appropriate 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.
      PubDate: 2017-08-02
      Issue No: Vol. 15, No. 2 (2017)
       
  • REMOTE CONTROL OF THE MECHATRONIC REDESIGNED SLIDER-CRANK MECHANISM IN
           SERVICE

    • Authors: Miša Tomić, Miloš Milošević, Nevena Tomić, Nenad D. Pavlović, Vukašin Pavlović
      Pages: 257 - 268
      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.
      PubDate: 2017-08-02
      Issue No: Vol. 15, No. 2 (2017)
       
  • DETERMINATION OF IMPORTANT PARAMETERS FOR PATENT APPLICATIONS

    • Authors: Dušan Marković, Dalibor Petković, Vlastimir Nikolić, Miloš Milovančević, Nebojša Denić
      Pages: 307 - 313
      Abstract: 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.
      PubDate: 2017-08-02
      Issue No: Vol. 15, No. 2 (2017)
       
  • THE MONOSPIRAL MOTORISED CABLE REEL IN CRANE APPLICATIONS

    • Authors: Vojkan Kostić, Nebojša Mitrović, Bojan Banković, Milutin Petronijević
      Pages: 315 - 330
      Abstract: The 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.
      PubDate: 2017-08-02
      Issue No: Vol. 15, No. 2 (2017)
       
  • MICROSTRUCTURE AND MICROMECHANICS OF SHALE ROCKS: CASE STUDY OF MARCELLUS
           SHALE

    • Authors: Hui Du, Kristen Carpenter, David Hui, Mileva Radonjic
      Pages: 331 - 340
      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.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.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.
      PubDate: 2017-08-02
      Issue No: Vol. 15, No. 2 (2017)
       
  • ALTERNATIVE METHOD FOR ON SITE EVALUATION OF THERMAL TRANSMITTANCE

    • Authors: Aleksandar Janković, Biljana Antunović, Ljubiša Preradović
      Pages: 341 - 351
      Abstract: Thermal 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.
      PubDate: 2017-08-02
      Issue No: Vol. 15, No. 2 (2017)
       
  • THERMAL BUCKLING ANALYSIS OF FUNCTIONALLY GRADED CIRCULAR PLATE RESTING ON
           THE PASTERNAK ELASTIC FOUNDATION VIA THE DIFFERENTIAL TRANSFORM METHOD

    • Authors: Fatemeh Farhatnia, Mahsa Ghanbari-Mobarakeh, Saeid Rasouli-Jazi, Soheil Oveissi
      Abstract: 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.
      PubDate: 2017-06-21
      DOI: 10.22190/FUME170104004F
      Issue No: Vol. 15, No. 1 (2017)
       
  • CRANIOFACIAL STRESS PATTERNS AND DISPLACEMENTS AFTER ACTIVATION OF HYRAX
           DEVICE: FINITE ELEMENT MODELLING

    • Authors: Sergei Bosiakov, Anastasiya Vinokurova, Andrei Dosta
      Abstract: 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.
      PubDate: 2017-06-21
      DOI: 10.22190/FUME161210012B
      Issue No: Vol. 15, No. 1 (2017)
       
  • FORCED CONVECTION DRYING OF INDIAN GROUNDNUT: AN EXPERIMENTAL STUDY

    • Authors: Ravinder Kumar Sahdev, Mahesh Kumar, Ashwani Kumar Dhingra
      Abstract: 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/m2 oC and 35.08 W/m2 oC, 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.
      PubDate: 2017-06-21
      DOI: 10.22190/FUME160812011S
      Issue No: Vol. 15, No. 1 (2017)
       
  • RADIAL FORCE IMPACT ON THE FRICTION COEFFICIENT AND TEMPERATURE OF A
           SELF-LUBRICATING PLAIN BEARING

    • Authors: Nada Bojić, Dragan Milčić, Milan Banić, Miroslav Mijajlović, Ružica Nikolić
      Abstract: Self-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.
      PubDate: 2017-06-21
      DOI: 10.22190/FUME160830010B
      Issue No: Vol. 15, No. 1 (2017)
       
  • MULTILAYERED PLATE ELEMENTS WITH NODE-DEPENDENT KINEMATICS FOR THE
           ANALYSIS OF COMPOSITE AND SANDWICH STRUCTURES

    • Authors: Stefano Valvano, Erasmo Carrera
      Pages: 1 - 30
      Abstract: In 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.
      PubDate: 2017-04-04
      DOI: 10.22190/FUME170315001V
      Issue No: Vol. 15, No. 1 (2017)
       
  • A 3-NODE PIEZOELECTRIC SHELL ELEMENT FOR LINEAR AND GEOMETRICALLY
           NONLINEAR DYNAMIC ANALYSIS OF SMART STRUCTURES

    • Authors: Gil Rama
      Pages: 31 - 44
      Abstract: Composite 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.
      PubDate: 2017-04-04
      DOI: 10.22190/FUME170225002R
      Issue No: Vol. 15, No. 1 (2017)
       
  • THERMAL EFFECT ON FREE VIBRATION AND BUCKLING OF A DOUBLE-MICROBEAM SYSTEM

    • Authors: Marija Stamenković Atanasov, Danilo Karličić, Predrag Kozić, Goran Janevski
      Pages: 45 - 62
      Abstract: The 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.
      PubDate: 2017-04-04
      DOI: 10.22190/FUME161115007S
      Issue No: Vol. 15, No. 1 (2017)
       
  • NORMAL LINE CONTACT OF FINITE-LENGTH CYLINDERS

    • Authors: Qiang Li, Valentin L. Popov
      Pages: 63 - 71
      Abstract: In 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.
      PubDate: 2017-04-04
      DOI: 10.22190/FUME170222003L
      Issue No: Vol. 15, No. 1 (2017)
       
  • IMPLEMENTATION OF THE LEAN-KAIZEN APPROACH IN FASTENER INDUSTRIES USING
           THE DATA ENVELOPMENT ANALYSIS

    • Authors: Sunil Kumar, Ashwani Kumar Dhingra, Bhim Singh
      Pages: 145 - 161
      Abstract: This 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.
      PubDate: 2017-04-04
      DOI: 10.22190/FUME161228007K
      Issue No: Vol. 15, No. 1 (2017)
       
  • FROM ART TO ENGINEERING: A TECHNICAL REVIEW ON THE PROBLEM OF VIBRATING
           CANVAS PART I: EXCITATION AND EFFORTS OF VIBRATION REDUCTION

    • Authors: Kerstin Kracht, Thomas Kletschkowski
      Pages: 163 - 182
      Abstract: 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.
      PubDate: 2017-04-04
      DOI: 10.22190/FUME161010009K
      Issue No: Vol. 15, No. 1 (2017)
       
  • MODELLING AND CONTROL OF H-SHAPED RACING QUADCOPTER WITH TILTING
           PROPELLERS

    • Authors: Ahmed Alkamachi, Ergun Ercelebi
      First page: 201
      Abstract: Traditional 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.
      PubDate: 2017-06-21
      DOI: 10.22190/FUME170203005A
      Issue No: Vol. 15, No. 1 (2017)
       
  • THE INFLUENCE OF VISCOELASTICITY ON VELOCITY-DEPENDENT RESTITUTIONS IN THE
           OBLIQUE IMPACT OF SPHERES

    • Authors: Emanuel Willert, Stephan Kusche, Valentin L. Popov
      First page: 269
      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.
      PubDate: 2017-06-21
      DOI: 10.22190/FUME170420006W
      Issue No: Vol. 15, No. 1 (2017)
       
  • FEATURES OF THE Σ5 AND Σ9 GRAIN BOUNDARIES MIGRATION IN BCC AND FCC
           METALS UNDER SHEAR LOADING – A MOLECULAR DYNAMICS STUDY

    • Authors: Andrey I. Dmitriev, Anton Yu. Nikonov
      First page: 285
      Abstract: Molecular 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.
      PubDate: 2017-06-21
      Issue No: Vol. 15, No. 1 (2017)
       
  • SIMULATION OF FRICTIONAL DISSIPATION UNDER BIAXIAL TANGENTIAL LOADING WITH
           THE METHOD OF DIMENSIONALITY REDUCTION

    • Authors: Andrey V. Dimaki, Roman Pohrt, Valentin L. Popov
      First page: 295
      Abstract: The 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.
      PubDate: 2017-06-21
      DOI: 10.22190/FUME170503007D
      Issue No: Vol. 15, No. 1 (2017)
       
  • A THEORETICAL-EXPERIMENTAL APPROACH FOR ELASTO-DAMPING PARAMETERS
           ESTIMATION OF CONE INERTIAL CRUSHER MOUNTING

    • Authors: Rosen Mitrev, Simeon Savov
      First page: 73
      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.
      PubDate: 2017-02-02
      DOI: 10.22190/FUME161013006M
      Issue No: Vol. 14, No. 3 (2017)
       
  • AN APPLICATION OF MULTICRITERIA OPTIMIZATION TO THE TWO-CARRIER TWO-SPEED
           PLANETARY GEAR TRAINS

    • Authors: Jelena Stefanović-Marinović, Sanjin Troha, Miloš Milovančević
      First page: 85
      Abstract: 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.
      PubDate: 2017-02-02
      DOI: 10.22190/FUME160307002S
      Issue No: Vol. 14, No. 3 (2017)
       
  • APPLICATION OF THE PERFORMANCE SELECTION INDEX METHOD FOR SOLVING
           MACHINING MCDM PROBLEMS

    • Authors: Dušan Petković, Miloš Madić, Miroslav Radovanović, Valentina Gečevska
      First page: 97
      Abstract: Complex 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.
      PubDate: 2017-02-02
      DOI: 10.22190/FUME151120001P
      Issue No: Vol. 14, No. 3 (2017)
       
  • DEEP DRAWING TECHNOLOGY WITH WALL IRONING IN MASS PACKAGING INDUSTRY

    • Authors: Saša Ranđelović, Mladomir Milutinović, Vladislav Blagojević
      First page: 107
      Abstract: Aluminum 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.
      PubDate: 2017-02-02
      DOI: 10.22190/FUME160831005R
      Issue No: Vol. 14, No. 3 (2017)
       
  • FUNCTION K - AS A LINK BETWEEN FUEL FLOW VELOCITY AND FUEL PRESSURE,
           DEPENDING ON THE TYPE OF FUEL

    • Authors: Boban Nikolić, Miloš Jovanović, Miloš Milošević, Saša Milanović
      First page: 119
      Abstract: Regarding 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.
      PubDate: 2017-02-02
      DOI: 10.22190/FUME160628003N
      Issue No: Vol. 14, No. 3 (2017)
       
  • IMPLANT MATERIAL SELECTION USING EXPERT SYSTEM

    • Authors: Miloš Ristić, Miodrag Manić, Dragan Mišić, Miloš Kosanović, Milorad Mitković
      First page: 133
      Abstract: 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.
      PubDate: 2017-02-02
      DOI: 10.22190/FUME160723004R
      Issue No: Vol. 14, No. 3 (2017)
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
Home (Search)
Subjects A-Z
Publishers A-Z
Customise
APIs
Your IP address: 54.167.231.97
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2016