Shahid Rajaee Teacher Training University (SRTTU)Journal of Computational & Applied Research in Mechanical Engineering (JCARME)2228-79226120160911An investigation into finding the optimum combination for dental restorations1951610.22061/jcarme.2016.516ENE.HomaeiDepartment of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Khorasan Razavi, 9177948944, IranK.FarhangdoostDepartment of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Khorasan Razavi, 9177948944, IranM.AkbariDental Research Center, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Khorasan Razavi, 9138813944, IranJournal Article20150716The aim of the study was to find the optimum combination of materials and thicknesses to provide a tough, damage resistant multi-layer system with numerical methods to restore the damaged teeth. Extended Finite Element Method (XFEM) was used to assess the critical loads for the onset of damage modes such as radial cracks and plastic deformation in dental prostheses, which consist of a brittle outerlayer (porcelain)/ metal (Au, Pd, Co)-core/ substrate (dentin) trilayer system. XFEM not only has the ability to model crack initiation process, but also could solve crack propagation problems. Generally speaking, porcelain layer shouldn't be thinner than 0.5 mm, as the stresses due to bending become tensile critically in porcelain undersurfaces and radial cracks would occur in low loads. Also, it could be concluded that XFEM in axisymmetric model could properly estimate crack initiation and propagation path. Yielding of metal core makes additional flexural stress at overlaying brittle surface and consequently, facilitates radial cracks. In dental applications, the optimum porcelain thickness would be between 0.75 and 1.25 mm. Furthermore, yield strength and stiffness of metal is better to be high sufficiently to prevent it from plastic deformation and ensuing radial cracks.https://jcarme.sru.ac.ir/article_516_89a2a6c9a33286f115e3912c77c3a226.pdfShahid Rajaee Teacher Training University (SRTTU)Journal of Computational & Applied Research in Mechanical Engineering (JCARME)2228-79226120160911Improvement of position measurement for 6R robot using magnetic encoder AS5045112051710.22061/jcarme.2016.517ENM. H.GhasemiRobotic Research Laboratory, Center of Excellence in Experimental Solid Mechanics and Dynamics, Faculty of Mechanical Engineering, Iran University of Science and Technology, 1684613114, Tehran, IranA. H.KorayemRobotic Research Laboratory, Center of Excellence in Experimental Solid Mechanics and Dynamics, Faculty of Mechanical Engineering, Iran University of Science and Technology, 1684613114, Tehran, IranS. R.NekooRobotic Research Laboratory, Center of Excellence in Experimental Solid Mechanics and Dynamics, Faculty of Mechanical Engineering, Iran University of Science and Technology, 1684613114, Tehran, IranM. H.KorayemRobotic Research Laboratory, Center of Excellence in Experimental Solid Mechanics and Dynamics, Faculty of Mechanical Engineering, Iran University of Science and Technology, 1684613114, Tehran, IranJournal Article20150111Recording the variation of joint angles as a feedback to the control unit is frequent in articulated arms. In this paper, magnetic sensor AS5045, which is a contactless encoder, is employed to measure joint angles of 6R robot and the performance of that is examined. The sensor has a low volume, two digital outputs and provides a high resolution measurement for users; furthermore its zero position is adjustable. Installation and use of this measurement system on 6R robot has been expressed by using output signals of sensor AS5045 in the digital control board of 6R and equipped with ARM processor LPC1768. First, a sample of digital board is used for controlling a DC motor in both speed and position, in order to investigate specifications of AS5045’s digital and analogue outputs. Simulation of 6R robot in point-to-point motion has been performed with MATLAB software using a proportional derivative (PD) controller. Then, experiment with the same condition and gains via a PD controller has been designed and implemented on the digital control board. The feedback system has been also checked in a circular path to show its advantages in trajectory tracking. The comparison of simulation results with experiments shows improvement: less error and better performance of 6R robot. This new setup omitted the noise of previous analogue feedback system since its digital outputs provides a precise measurement.https://jcarme.sru.ac.ir/article_517_1dba95f4b73c3b350d6bd5d57e1b541f.pdfShahid Rajaee Teacher Training University (SRTTU)Journal of Computational & Applied Research in Mechanical Engineering (JCARME)2228-79226120160911Hydraulic anti-lock, anti-skid braking system using fuzzy controller213751810.22061/jcarme.2016.518ENM.MaghrooryDepartment of Electrical Engineering, Tehran, Shahid Rajaee Teacher Training University, P.O.B. 16785136, IranA.FarhadiDepartment of Mechanical Engineering, Tehran, Shahid Rajaee Teacher Training University, P.O.B. 16785136, IranP.NaderiDepartment of Electrical Engineering, Tehran, Shahid Rajaee Teacher Training University, P.O.B. 16785136, IranJournal Article20150907To maintain the stability trajectory of vehicles under critical driving conditions, anti lock-anti skid controllers, consisting of four anti-lock sub-controllers for each wheel and two anti-skid sub-controllers for left and right pair wheels have been separately designed. Wheel and body systems have been simulated with seven degrees of freedom to evaluate the proper functioning of controllers. Anti-lock controllers control brake torque through persistent monitoring of wheels velocity and acceleration and prevent them from locking up by cutting and releasing the brake fluid flow into wheel brake cylinder. On the other hand, anti-skid controllers have been designed in order to maintain the vehicle along a stable trajectory, calculated from the stable spin theory, and to monitor the vehicle’s trajectory during braking. This controller maintains the vehicle along the desirable trajectory by monitoring vehicle yaw angle and comparing it with the reference yaw angle, and also by adjusting the level of brake fluid input into each wheel’s caliper, and subsequently by adjusting brake torque. At the end of the current research, the use of yaw rate control input in place of yaw angle control input in anti-skid controllers has been suggested through a comparative analysis.https://jcarme.sru.ac.ir/article_518_c2f652d9f42862d5bbf706bcb515a6ea.pdfShahid Rajaee Teacher Training University (SRTTU)Journal of Computational & Applied Research in Mechanical Engineering (JCARME)2228-79226120160911Optimization of the injection molding process of Derlin 500 composite using ANOVA and grey relational analysis395051910.22061/jcarme.2016.519ENS.KhalilpourazaryFaculty of Mechanical Engineering, Urmia University of Technology, Urmia, IranN.PayamProjects Engineering Department, Mapna Boiler & Equipment Engineering & Manufacturing Co., Karaj, IranJournal Article20150218Warpage and shrinkage control are important factors in proving the quality of thin-wall parts in injection modeling process. In the present paper, grey relational analysis was used in order to optimize these two parameters in manufacturing plastic bush of articulated garden tractor. The material used in the plastic bush is Derlin 500. The input parameters in the process were selected according to their effect on shrinkage and warpage values, melt temperature, mold temperature, injection rate, injection pressure, and packing pressure. Then, the Taguchi method was applied to design the experiments, and through the use of Mold Flow software injection molding process was simulated based on these experiments and the input parameters. Based on the results obtained from the simulation, the input parameters were analyzed in three levels using grey relational analysis. Then, analysis of variance and confirmation tests were carried out on the output of grey relational analysis to predict the optimum values of the input parameters and to calculate the dimensional changes of the plastic bush. Gaining these values, the plastic bush sample was manufactured, and its 3D point cloud model was generated by a scanner. At the end, by generating 3D solid model of the plastic bush its dimensional features were studied. The comparison of the warpage and shrinkage values between grey relational analysis and 3D CAD model indicates the precision of the method in controlling and measuring these two parameters. https://jcarme.sru.ac.ir/article_519_7db89275a5f5bcb1befcb6e9a32c006d.pdfShahid Rajaee Teacher Training University (SRTTU)Journal of Computational & Applied Research in Mechanical Engineering (JCARME)2228-79226120160911A new strategy for controlling wind turbines against sensor faults and wake effects to harvest more electrical energy516452010.22061/jcarme.2016.520ENSeyed VahabShojaediniDepartment of Electrical Engineering and Information Technology, Iranian Research Organization for Science and TechnologyArminParsiannejadDepartment of Mechanical Engineering, Hakim Sabzevari universityJournal Article20150815This paper describes a new method for harvesting maximum electrical energy in wind farms. In proposing technique, the stochastic process principles are applied for detecting fault measurements of sensors. On the other hand, the wind farm is modeled by using fuzzy concept. Thereby the turbines are controlled against continuous changes in speed, direction and eddy currents of the blowing wind. To evaluate the performance of the proposed method three practical conditions of wind blowing are simulated. In the first scenario, the normal wind is simulated with low turbulence and slow changes. The second scenario belongs to high turbulence winds with sudden shifts in their parameters, and finally in the most complex scenario, several eddy currents are considered in blowing winds too. The obtained results show that the proposed method provides greater and more uniform harvested power compared to alternative methods. Furthermore, its superiority against other techniques has increased in parallel with the scenario become more complicated.https://jcarme.sru.ac.ir/article_520_59a3cdd866d709a3c542f7cc577b84b5.pdfShahid Rajaee Teacher Training University (SRTTU)Journal of Computational & Applied Research in Mechanical Engineering (JCARME)2228-79226120160911Resonant frequency of bimorph triangular V-shaped piezoelectric cantilever energy harvester657352110.22061/jcarme.2016.521ENRouhollahHosseiniYoung Researchers and Elite Club, South Tehran Branch, Islamic Azad University, Tehran, IranMohsenHamediProfessor, Faculty of Mechanical Engineering, University of Tehran, TehranJournal Article20150417The concept of “energy harvesting” is to design smart systems to capture the ambient energy and to convert it to usable electrical power for supplying small electronics devices and sensors. The goal is to develop autonomous and self-powered devices that do not need any replacement of traditional electrochemical batteries. Now piezoelectric cantilever structures are being used to harvest vibration energy for self-powered devices. However, the geometry of a piezoelectric cantilever beam will greatly affect its vibration energy harvesting ability. This paper deduces a remarkably precise analytical formula for calculating the fundamental resonant frequency of bimorph V-shaped cantilevers using Rayleigh method. This analytical formula, which is convenient for mechanical energy harvester design based on Piezoelectric effect, is then validated by ABAQUS simulation. This formula raises a new perspective that, among all the bimorph V-shaped cantilevers and in comparison with rectangular one, the simplest tapered cantilever beam can lead to maximum resonant frequency and highest sensitivity. The derived formula can be commonly used as a relatively precise rule of thumb in such systems.https://jcarme.sru.ac.ir/article_521_8a3006f072de361991672299e6e74403.pdfShahid Rajaee Teacher Training University (SRTTU)Journal of Computational & Applied Research in Mechanical Engineering (JCARME)2228-79226120160911A truly meshless method formulation for analysis of non-Fourier heat conduction in solids758952210.22061/jcarme.2016.522ENIsaAhmadiAdvanced Materials and Computational Mechanics Lab., Department of Mechanical Engineering, University of Zanjan, P.O.Box: 45371-38791, Zanjan, IranJournal Article20151011The non-Fourier effect in heat conduction is important in strong thermal environments and thermal shock problems. Generally, commercial FE codes are not available for analysis of non-Fourier heat conduction. In this study, a meshless formulation is presented for the analysis of the non-Fourier heat conduction in the materials. The formulation is based on the symmetric local weak form of the second-order non-Fourier heat conduction equation in terms of the temperature. Using the local weak form of heat transfer equations in the sub-domains, the governing equation of the non-Fourier heat conduction is discretized in the space domain to the second order ordinary differential equations for the time. The discretized equations are integrated into the time domain with an appropriate finite difference method. The fictitious numerical oscillations are completely suppressed from the front of temperature waves in the presented method. An analytical series solution is developed for the non-Fourier heat transfer in one-dimensional heat transfer for special boundary conditions and the accuracy of presented numerical meshless method is validated by comparison of the results of the numerical meshless solution and the series solution. The numerical results are presented for non-Fourier heat conduction for various Vernotte numbers and boundary conditions and the results are compared with the results of the classical Fourier heat conduction.https://jcarme.sru.ac.ir/article_522_fbd48c83fa855b64d129b7ed099a9708.pdf