Amirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Modeling and Optimization of Vibration Absorber Beam Combined with Magneto-Electro-Elastic Energy HarvesterModeling and Optimization of Vibration Absorber Beam Combined with Magneto-Electro-Elastic Energy Harvester12231248480110.22060/mej.2022.20669.7291FAZahraRajaeiDepartment of Mechanical Engineering, Engineering Faculty, Bu_Ali Sina University, Hamedan, IranAlirezaShoshtariDepartment of Mechanical Engineering, Bu-Ali Sina University, Hamedan, IranJournal Article20211013Mechanical structures are always exposed to unwanted vibrations and this can greatly affect system performance. The energy from this vibration can be used as a source to generate voltage. Therefore, the use of a vibration absorber that can minimize the vibrations of the structure and at the same time be used as an energy harvesting has been very important. In recent years, the use of intelligent materials capable of generating voltage has made significant progress in various fields. In the present study, a continuous beam with a layer of magnetoelectroelastic materials has been used as a dynamic absorber. This absorber helps to reduce the vibrations of the system by one degree of freedom and extracts energy from it. The best performance of this absorber will occur at the resonant frequency. The general absorber equations were extracted and the effect of different beam parameters on energy harvesting was investigated. Using the optimization method, appropriate values were obtained to achieve both goals. The studies were performed in the first three modes of the Bernoulli Euler beam. the highest energy harvesting occurred in the first mode and in the frequency range of 10 to 40 Hz. The vibrations of the main structure also decreased by about 65%.Mechanical structures are always exposed to unwanted vibrations and this can greatly affect system performance. The energy from this vibration can be used as a source to generate voltage. Therefore, the use of a vibration absorber that can minimize the vibrations of the structure and at the same time be used as an energy harvesting has been very important. In recent years, the use of intelligent materials capable of generating voltage has made significant progress in various fields. In the present study, a continuous beam with a layer of magnetoelectroelastic materials has been used as a dynamic absorber. This absorber helps to reduce the vibrations of the system by one degree of freedom and extracts energy from it. The best performance of this absorber will occur at the resonant frequency. The general absorber equations were extracted and the effect of different beam parameters on energy harvesting was investigated. Using the optimization method, appropriate values were obtained to achieve both goals. The studies were performed in the first three modes of the Bernoulli Euler beam. the highest energy harvesting occurred in the first mode and in the frequency range of 10 to 40 Hz. The vibrations of the main structure also decreased by about 65%.https://mej.aut.ac.ir/article_4801_0c7119e3a6a2209da6a5b90e5b5b75bd.pdfAmirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Pattern Recognition of Unbalanced Rigid Rotor Bearing ForcesPattern Recognition of Unbalanced Rigid Rotor Bearing Forces12491270485210.22060/mej.2022.20592.7267FAMohammad RezaHomaeinezhadK. N. Toosi University Of Technology, No. 17, Pardis Street, Mollasadra Ave., Vanak Square, Tehran, Iran. P.O Box: 19395-1999, Postal Code: 19991-43344.Tel: (+98 21) 84063284, Mobile: (+98) 9121899445, Fax: (+98 21) 88677274.0000-0003-4329-649XMohammad HoseinSaeidi MostaghimK. N. Toosi University Of Technology, No. 17, Pardis Street, Mollasadra Ave., Vanak Square, Tehran, Iran. P.O Box: 19395-1999, Postal Code: 19991-43344.Tel: (+98 21) 84063284, Mobile: (+98) 9121899445, Fax: (+98 21) 88677274.FarnoodArabK. N. Toosi University Of Technology, No. 17, Pardis Street, Mollasadra Ave., Vanak Square, Tehran, Iran. P.O Box: 19395-1999, Postal Code: 19991-43344.Tel: (+98 21) 84063284, Mobile: (+98) 9121899445, Fax: (+98 21) 88677274.Journal Article20210923In industrial rotatory machines, different forces in rotor bearings are generated due to various impaired mechanical sources, namely bearing misalignment and nonhomogeneous mass distribution (unbalance). By precisely analyzing and diagnosing the produced patterns of bearing forces, one can determine the unbalance parameters such as quantities of masses, their distance from the rotational axis, and characteristics of corresponding parallel planes. Consequently, it will be possible to formulate pragmatic protocols according to which the maintenance engineers of rotatory systems will pinpoint properties of problematic imbalance masses and then straightforwardly balance them. In the procedure of conducting this research, several exemplary imbalance masses are deployed on a rotatory mechanical shaft and the equations of motion and forces in perfectly aligned rigid bearings are extracted. Then, by applying a neural network-oriented system the patterns of bearing forces are recognized and the characteristics of the nominal masses including magnitudes, distances from the rotational axis, angles as well as the unbalance type are determined. The accuracy of predicting 8 variables of balancing masses was 41% and after eliminating the redundant overlaps from principal components, the accuracy of predicted 5 variables of balancing masses significantly increased to 95%. Also, by implementing another comprehensive neural network system, it was shown that by exerting two separate balancing masses, the applicability of this method in balancing any faulty systems with dynamic unbalance is possible.In industrial rotatory machines, different forces in rotor bearings are generated due to various impaired mechanical sources, namely bearing misalignment and nonhomogeneous mass distribution (unbalance). By precisely analyzing and diagnosing the produced patterns of bearing forces, one can determine the unbalance parameters such as quantities of masses, their distance from the rotational axis, and characteristics of corresponding parallel planes. Consequently, it will be possible to formulate pragmatic protocols according to which the maintenance engineers of rotatory systems will pinpoint properties of problematic imbalance masses and then straightforwardly balance them. In the procedure of conducting this research, several exemplary imbalance masses are deployed on a rotatory mechanical shaft and the equations of motion and forces in perfectly aligned rigid bearings are extracted. Then, by applying a neural network-oriented system the patterns of bearing forces are recognized and the characteristics of the nominal masses including magnitudes, distances from the rotational axis, angles as well as the unbalance type are determined. The accuracy of predicting 8 variables of balancing masses was 41% and after eliminating the redundant overlaps from principal components, the accuracy of predicted 5 variables of balancing masses significantly increased to 95%. Also, by implementing another comprehensive neural network system, it was shown that by exerting two separate balancing masses, the applicability of this method in balancing any faulty systems with dynamic unbalance is possible.https://mej.aut.ac.ir/article_4852_5cf68969fb67aa6082363a6d4e6468e2.pdfAmirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Nonlinear Torsional Vibrations of Axially Loaded Pretwisted Beam with Primary Resonance ExcitationsNonlinear Torsional Vibrations of Axially Loaded Pretwisted Beam with Primary Resonance Excitations12711302481210.22060/mej.2022.20718.7301FASeyed AliSinaصنعتی شاهرود-مهندسی مکانیکHassanHaddadpourDept. of Aerospace Engineering, Sharif Univ. of Tech.Journal Article20211028Frequently used thin walled beams have low torsional stiffness and their torsional deformations may be of such magnitudes that it is not adequate to treat the angles of cross section rotation as small. In this paper, nonlinear torsional vibrations of thin walled beams will be investigated. The method of multiple scales will be implemented as a solution method and different nonlinear phenomena will be studied. The obtained results are compared with the available results in the literature which reveals an excellent agreement between different solution methodologies. The outcomes of this study show that beam nonlinear torsional dynamics and the related phenomena could influence the linear torsional dynamic of beams under axial load, e.g. rotating beams. Forced torsional vibrations of a beam with the excitation in the form of primary resonance of the first and second modes have been investigated. It has been demonstrated that in the case of the beam with two ends clamped boundary conditions, three-to-one internal resonance will appear. The primary resonance of the first and second modes has been solved in two sets of boundary conditions, torsionally clamped-fixed and torsionally fixed-fixed. Nonlinear response, amplitude-phase equations, fixed points, and their stability have been studied.Frequently used thin walled beams have low torsional stiffness and their torsional deformations may be of such magnitudes that it is not adequate to treat the angles of cross section rotation as small. In this paper, nonlinear torsional vibrations of thin walled beams will be investigated. The method of multiple scales will be implemented as a solution method and different nonlinear phenomena will be studied. The obtained results are compared with the available results in the literature which reveals an excellent agreement between different solution methodologies. The outcomes of this study show that beam nonlinear torsional dynamics and the related phenomena could influence the linear torsional dynamic of beams under axial load, e.g. rotating beams. Forced torsional vibrations of a beam with the excitation in the form of primary resonance of the first and second modes have been investigated. It has been demonstrated that in the case of the beam with two ends clamped boundary conditions, three-to-one internal resonance will appear. The primary resonance of the first and second modes has been solved in two sets of boundary conditions, torsionally clamped-fixed and torsionally fixed-fixed. Nonlinear response, amplitude-phase equations, fixed points, and their stability have been studied.https://mej.aut.ac.ir/article_4812_7c022d9c6dd601e087e186ee6dfe1fc7.pdfAmirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Study of Nonlinear Vibration Behavior of an Electric Current-Carrying Ferromagnetic Plate in Magnetic FieldStudy of Nonlinear Vibration Behavior of an Electric Current-Carrying Ferromagnetic Plate in Magnetic Field13031318481110.22060/mej.2022.20221.7196FANarimanAshrafi Khorasaniهییت علمیElhamTahmasebiPhD studentJournal Article20210630In the present study, considering the magnetic tractions and heat generated by electric current and eddy current, new nonlinear equations have been proposed to investigate the vibrational behavior of ferromagnetic plates carrying an electric current under a magnetic field. After extracting the governing differential equations of the system using Newton's second law, the coupled nonlinear equations are discretized using the Galerkin method and then solved numerically. The numerical results presented in the present study are compared with the results in the technical literature and then the effect of different parameters on the vibration characteristics of soft ferromagnetic plates is investigated. The results show that the magnetic field and electric current have a significant effect on the vibration behavior of the plate and lead to an increase in the amplitude oscillations of the system. The presence of a magnetic field reduces the equivalent stiffness of the plate and increases it, resulting in static instability in the system. Also, by considering the force created by magnetic tractions, a static rise is created in the plate and affects its steady-state response. In the study of thermal effects, it was found that the assumption of thermal coupling increases the natural frequency of the plate. In the present study, considering the magnetic tractions and heat generated by electric current and eddy current, new nonlinear equations have been proposed to investigate the vibrational behavior of ferromagnetic plates carrying an electric current under a magnetic field. After extracting the governing differential equations of the system using Newton's second law, the coupled nonlinear equations are discretized using the Galerkin method and then solved numerically. The numerical results presented in the present study are compared with the results in the technical literature and then the effect of different parameters on the vibration characteristics of soft ferromagnetic plates is investigated. The results show that the magnetic field and electric current have a significant effect on the vibration behavior of the plate and lead to an increase in the amplitude oscillations of the system. The presence of a magnetic field reduces the equivalent stiffness of the plate and increases it, resulting in static instability in the system. Also, by considering the force created by magnetic tractions, a static rise is created in the plate and affects its steady-state response. In the study of thermal effects, it was found that the assumption of thermal coupling increases the natural frequency of the plate. https://mej.aut.ac.ir/article_4811_810bf83c7adfd8a04ac1f11508bab9e0.pdfAmirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Enhanced Extended State Observer Based on Trajectory Linearization Control for External and Internal DisturbancesEnhanced Extended State Observer Based on Trajectory Linearization Control for External and Internal Disturbances13191340480910.22060/mej.2022.20402.7236FAJavidHosseinpourFaculty of Aerospace Engineering, Malek Ashtar University of Technology, Tehran, IranS.hosseinSadatiAerospace Engineering -Malek Ashtar UniversityYosefAbbasiAerospace, Malek-Ashtar, Tehran, IranFirouzAllahverdizadehFaculty of Electrical Engineering, Malek Ashtar University of Technology, Tehran, IraJournal Article20210825<span style="letter-spacing: .05pt;">This paper proposes a novel hybrid control framework by combing enhanced extended state observer with trajectory linearization control for air vehicle acceleration tracking problems</span>. First, based on the tracking error dynamics derived by Taylor expansion for the original nonlinear system along the desired trajectory, a feedback linearization-based control law is designed to stabilize a linear time-varying system. To reduce the controller performance sensitivity to uncertainties, with partial model information, an <span style="letter-spacing: .05pt;">enhanced extended state observer </span>is constructed to estimate the tracking error vector, as well as the uncertainties in an integrated manner. The closed-loop stability of the system under the proposed compound scheme is established. Both numerical simulation studies and an application example of <span style="letter-spacing: .05pt;">air vehicle</span> acceleration autopilot design demonstrate the feasibility and efficacy of the proposed method.<span style="letter-spacing: .05pt;">This paper proposes a novel hybrid control framework by combing enhanced extended state observer with trajectory linearization control for air vehicle acceleration tracking problems</span>. First, based on the tracking error dynamics derived by Taylor expansion for the original nonlinear system along the desired trajectory, a feedback linearization-based control law is designed to stabilize a linear time-varying system. To reduce the controller performance sensitivity to uncertainties, with partial model information, an <span style="letter-spacing: .05pt;">enhanced extended state observer </span>is constructed to estimate the tracking error vector, as well as the uncertainties in an integrated manner. The closed-loop stability of the system under the proposed compound scheme is established. Both numerical simulation studies and an application example of <span style="letter-spacing: .05pt;">air vehicle</span> acceleration autopilot design demonstrate the feasibility and efficacy of the proposed method.https://mej.aut.ac.ir/article_4809_a5bad363fc47f424ddf5091c8471480a.pdfAmirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Experimental Study and Finite Element Simulation of Cutting Tool Temperature in Laser Assisted MachiningExperimental Study and Finite Element Simulation of Cutting Tool Temperature in Laser Assisted Machining13411356474110.22060/mej.2022.20462.7234FASayed MohammadNikoueiAmirkabir university of technologyMohammad RezaRazfarDepartment of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran.MohsenKhajehzadehMechanical Engineering Department of Amirkabir University of TechnologyJournal Article20210824The present paper has been dedicated to finite element simulation and experimental study of cutting tool temperature during laser-assisted machining. To achieve this objective, a finite element model of the processes has been developed for Inconel 718 super alloy and the results have been verified by experimental measurements of cutting forces and cutting tool temperature. In this regard, first of all, a finite element model of the laser-assisted turning process was developed and then an experimental setup was designed and manufactured. Finally, a series of experimental tests were arranged to achieve a proper range of process parameters and also to measure cutting forces and cutting tool temperatures during the machining process. Experimental results were then used to verify the results of the finite element model. Using the developed model, the effect of laser source power, cutting speed, and feed on cutting tool temperature were studied. According to the achieved results, using a laser heat source, in the range without microstructural effects, will lead to a 25% reduction in the average main component of cutting force and an 80% reduction in the average maximum temperature of the cutting tool in comparison to conventional turning.The present paper has been dedicated to finite element simulation and experimental study of cutting tool temperature during laser-assisted machining. To achieve this objective, a finite element model of the processes has been developed for Inconel 718 super alloy and the results have been verified by experimental measurements of cutting forces and cutting tool temperature. In this regard, first of all, a finite element model of the laser-assisted turning process was developed and then an experimental setup was designed and manufactured. Finally, a series of experimental tests were arranged to achieve a proper range of process parameters and also to measure cutting forces and cutting tool temperatures during the machining process. Experimental results were then used to verify the results of the finite element model. Using the developed model, the effect of laser source power, cutting speed, and feed on cutting tool temperature were studied. According to the achieved results, using a laser heat source, in the range without microstructural effects, will lead to a 25% reduction in the average main component of cutting force and an 80% reduction in the average maximum temperature of the cutting tool in comparison to conventional turning.https://mej.aut.ac.ir/article_4741_a5585a4d4b12277fee5cad0880611bc6.pdfAmirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Investigation of Failure Mechanism of the Composite Tubes Made by Filament Winding Process by Acoustic Emission MethodInvestigation of Failure Mechanism of the Composite Tubes Made by Filament Winding Process by Acoustic Emission Method13571372475410.22060/mej.2022.20663.7292FASajadAlimirzaeiMechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran0000-0002-2265-6540MehdiAhmadi NajafabadiMechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, IranAmirBani Mohmmad AliMechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, IranJournal Article20211014To study the energy absorption features in composite structures, it is necessary to identify the functional mechanisms and determine the impact of each on the energy absorption. In this study, the behavior of composite tubes under compressive axial load was investigated by acoustic emission monitoring. To make a filament wound composite tube, the optimal parameters were first determined using literature. In determining the optimal parameters, due to the uncertainty effect of fiber angles, from the intermediate range, the angle of 35 degrees was selected. Then, to ensure the experimental results, the finite element simulation method and the use of the VUMAT subroutine based on the 3D Hashin criterion were used. The results showed that the dominant failure mode was a local shear failure and lateral damage, which first caused the plastic deformation of the sample and then caused the growth of cracks in the fiber direction. Also, the highest percentage of failure mechanisms are matrix cracking, fiber breakage, and separation of fibers from the matrix, respectively. Finally, the use of the developed subroutine to predict the behavior of the structure was useful and was able to predict the behavior of the composite tube even after the maximum crushing force.To study the energy absorption features in composite structures, it is necessary to identify the functional mechanisms and determine the impact of each on the energy absorption. In this study, the behavior of composite tubes under compressive axial load was investigated by acoustic emission monitoring. To make a filament wound composite tube, the optimal parameters were first determined using literature. In determining the optimal parameters, due to the uncertainty effect of fiber angles, from the intermediate range, the angle of 35 degrees was selected. Then, to ensure the experimental results, the finite element simulation method and the use of the VUMAT subroutine based on the 3D Hashin criterion were used. The results showed that the dominant failure mode was a local shear failure and lateral damage, which first caused the plastic deformation of the sample and then caused the growth of cracks in the fiber direction. Also, the highest percentage of failure mechanisms are matrix cracking, fiber breakage, and separation of fibers from the matrix, respectively. Finally, the use of the developed subroutine to predict the behavior of the structure was useful and was able to predict the behavior of the composite tube even after the maximum crushing force.https://mej.aut.ac.ir/article_4754_84899ae725ba49884f4c85c086f1b340.pdfAmirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Optimization of Characteristics and Construction of Composite Bipolar Plates of Polymer Fuel CellsOptimization of Characteristics and Construction of Composite Bipolar Plates of Polymer Fuel Cells13731390479010.22060/mej.2022.20762.7319FAMatinMohammadzadehdepartment of mechanical engineering,, Amirkabir University of TechnologyMojtabaGhadimiMalek Ashtar University of Technology, Fuel Cell Technology Research Laboratory, Tehran, IranMohammadMomenifarDepartment of mechanical engineering, Malek Ashtar university of technology, IranJournal Article20211124<span style="letter-spacing: .05pt;">This study investigates the construction of polymer/graphic composite bipolar plates via hot compression molding for use in polymer fuel cells and the optimization of characteristics by experimental test design. For this purpose, the Minitab software is used. Besides, this study examined the physical, mechanical, and electrical characteristics of the constructed bipolar plates by performing the tests of water absorption, calculation of density, the test bending strength, interfacial contact resistance, and electrical conductance. The pressure and the curing time were considered as the input parameters of the optimization, and the goal is to optimize the flexural strength and interfacial contact resistance to achieve the United States Department of Energy's 2020 target for the bipolar plates of polymer fuel cells. The results show that with a pressure of 79.499 MPa and the curing time under pressure was 70s, the parameters of flexural strength and optimum interfacial contact resistance are 53.91 MPa and 10.57 mΩ.cm<sup>2</sup>, respectively. The properties also include water absorption and electrical conductivity in the through-plane direction of 0.36 percent and 27.22 (S/m) respectively, which is in line with the goals of the United States Department of Energy.</span><span style="letter-spacing: .05pt;">This study investigates the construction of polymer/graphic composite bipolar plates via hot compression molding for use in polymer fuel cells and the optimization of characteristics by experimental test design. For this purpose, the Minitab software is used. Besides, this study examined the physical, mechanical, and electrical characteristics of the constructed bipolar plates by performing the tests of water absorption, calculation of density, the test bending strength, interfacial contact resistance, and electrical conductance. The pressure and the curing time were considered as the input parameters of the optimization, and the goal is to optimize the flexural strength and interfacial contact resistance to achieve the United States Department of Energy's 2020 target for the bipolar plates of polymer fuel cells. The results show that with a pressure of 79.499 MPa and the curing time under pressure was 70s, the parameters of flexural strength and optimum interfacial contact resistance are 53.91 MPa and 10.57 mΩ.cm<sup>2</sup>, respectively. The properties also include water absorption and electrical conductivity in the through-plane direction of 0.36 percent and 27.22 (S/m) respectively, which is in line with the goals of the United States Department of Energy.</span>https://mej.aut.ac.ir/article_4790_9a02387b02ce7de2dac4b925892f68fb.pdfAmirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Theoretical Analysis of the Effects of Hardening Laws, Normal and Through Thickness Shear Stresses on Forming Limit Curves of AA6016-T4Theoretical Analysis of the Effects of Hardening Laws, Normal and Through Thickness Shear Stresses on Forming Limit Curves of AA6016-T413911408479310.22060/mej.2022.20811.7318FASoheilaSojodiFaculty of Mechanical Engineering, University of Guilan, Rasht, IranAliBastiFaculty of Mechanical Engineering, University of Guilan, Rasht, IranSeyed RezaFalahatgarFaculty of Mechanical Engineering, University of Guilan, Rasht, Iran0000-0003-1573-5619Seyedeh MaryamMirfalah NasiriFaculty of Mechanical Engineering, University of Guilan, Rasht, IranJournal Article20211122Forming limit Curves are one of the common tools to predict the necking in various forming processes. In this study, the Marciniak-Kuczynski instability theory by applying the Gotoh yield function is utilized to estimate the forming limit curves for the AA6016-T4 aluminum sheet in plane stress conditions. Also, the effect of three different hardening models including Swift, Voce, and a linear combination of the Swift and Voce models to determine the limit curves are investigated. The comparison between the theoretical forming limit curves and experimental results from the Nakajima test determines the accuracy of the hardening models in predicting the limit strains. Since in many new forming processes such as hydroforming and incremental sheet forming processes, investigation of the process in plane stress state is not an exact assumption, Therefore, in continuation of the paper, generalized forming limit curves are plotted based on the developed Marciniak-Kuczynski model by extending the Gotoh yield function, and the effect of compressive normal stress and through-thickness shear stress on forming limits of the sheet are investigated. The results indicated that by applying the compressive normal stress and through-thickness shear stresses, the limit strains increase, and the formability is improved, in contrast, limit stresses move down in the diagram.Forming limit Curves are one of the common tools to predict the necking in various forming processes. In this study, the Marciniak-Kuczynski instability theory by applying the Gotoh yield function is utilized to estimate the forming limit curves for the AA6016-T4 aluminum sheet in plane stress conditions. Also, the effect of three different hardening models including Swift, Voce, and a linear combination of the Swift and Voce models to determine the limit curves are investigated. The comparison between the theoretical forming limit curves and experimental results from the Nakajima test determines the accuracy of the hardening models in predicting the limit strains. Since in many new forming processes such as hydroforming and incremental sheet forming processes, investigation of the process in plane stress state is not an exact assumption, Therefore, in continuation of the paper, generalized forming limit curves are plotted based on the developed Marciniak-Kuczynski model by extending the Gotoh yield function, and the effect of compressive normal stress and through-thickness shear stress on forming limits of the sheet are investigated. The results indicated that by applying the compressive normal stress and through-thickness shear stresses, the limit strains increase, and the formability is improved, in contrast, limit stresses move down in the diagram.https://mej.aut.ac.ir/article_4793_b28d8e3ccb1ff9d46fa2d9e70222c9e7.pdfAmirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Experimental Investigation of Electrochemical Finishing Process Using Box-Behnken Design in Response Surface MethodologyExperimental Investigation of Electrochemical Finishing Process Using Box-Behnken Design in Response Surface Methodology14091422480210.22060/mej.2022.20708.7299FABahmanNematiدانشگاه زنجان گروه مهندسی مکانیکRasoulMoharramiگروه مهندسی مکانیک، دانشکده مهندسی، دانشگاه زنجان،Mohammad MostafaMohammadiزنجان-مهندسی- گروه مهندسی مکانیکJournal Article20211025Electrochemical polishing is a nontraditional finishing process by which the surface roughness of the metallic workpiece is reduced due to anodic dissolution. In this process, an electrochemical cell is formed using the workpiece as the anode, a tool as the cathode, and a power supply. Different parameters like inter electrode gap, the chemical composition of the electrolyte, and its temperature along with the electric potential affect the finishing performance. The important performance parameters are surface roughness, material removal rate, and the dimensional tolerance of the workpiece. In this article, the effect of inter electrode gap, cathode geometry, tool feed rate, and electric potential on the process outputs are evaluated experimentally. Due to the high number of input and output variables and possible interactions between the input variables, Box-Behnken design in response surface methodology is selected for designing the experiments. The experimental models are evaluated by analysis of variance. Using the response surface methodology, the effect of input parameters on process outputs and the possible interactions between the input variables are extracted. Also, multi-objective optimization is performed for determining the input variables which are adequate for maximizing the material removal rate along with achieving a predetermined amount for surface smoothness and geometric tolerance.Electrochemical polishing is a nontraditional finishing process by which the surface roughness of the metallic workpiece is reduced due to anodic dissolution. In this process, an electrochemical cell is formed using the workpiece as the anode, a tool as the cathode, and a power supply. Different parameters like inter electrode gap, the chemical composition of the electrolyte, and its temperature along with the electric potential affect the finishing performance. The important performance parameters are surface roughness, material removal rate, and the dimensional tolerance of the workpiece. In this article, the effect of inter electrode gap, cathode geometry, tool feed rate, and electric potential on the process outputs are evaluated experimentally. Due to the high number of input and output variables and possible interactions between the input variables, Box-Behnken design in response surface methodology is selected for designing the experiments. The experimental models are evaluated by analysis of variance. Using the response surface methodology, the effect of input parameters on process outputs and the possible interactions between the input variables are extracted. Also, multi-objective optimization is performed for determining the input variables which are adequate for maximizing the material removal rate along with achieving a predetermined amount for surface smoothness and geometric tolerance.https://mej.aut.ac.ir/article_4802_137bdd55f159c4f5556391f53e608f2e.pdfAmirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Numerical Investigation of Elastoplastic and Damage Behavior of Cortical Bone by Applying a New Damage ModelNumerical Investigation of Elastoplastic and Damage Behavior of Cortical Bone by Applying a New Damage Model14231442482710.22060/mej.2022.20773.7310FAMasoudNasiriSchool of Mechanic Engineering, Arak University,
Arak, IranMojtabaZolfaghariاراک-مهندسی مکانیکVahidTahmasbiصنعتی اراک-مهندسی مکانیکHamedHeydariSchool of Mechanic Engineering, Shahrekord University,
Shahrekord, IranJournal Article20211110Due to the need for orthopedic surgery, the mechanical behavior of the cortical bone in cyclic loading and physiological strain rate has been investigated. The emphasis is on developing a structural law that can establish the behavior during loading, unloading and reloading observed in experiments. These models will be formulated by combining rheological elements and energy principles. First, two one-dimensional models independent of the strain rate are formulated, one with one damage variable and the other with two different damage variables in tension and compression, are examined, and using laboratory data, the coefficients of each model are obtained. By comparing the simulation results and laboratory data, the necessary modifications have been made to the models. Finally, by combining the Bresler-Pister anisotropic yield criterion and the one-dimensional model independent of the rate associated with the two damage variables, the corresponding three-dimensional model was obtained. This three-dimensional model was implemented in the form of an explicit finite element method and the result showed acceptable compatibility with the simulation results of the one-dimensional model and experimental data. This three-dimensional model will be suitable for simulating complex geometries. The coefficient of determination for one-dimensional modelsRI ,RI± ,RI , RI±and has been modified and the three-dimensional model has obtained values of 0.882174, 0.965665, 0.995508, 0.996279, and 0.984866, respectively.Due to the need for orthopedic surgery, the mechanical behavior of the cortical bone in cyclic loading and physiological strain rate has been investigated. The emphasis is on developing a structural law that can establish the behavior during loading, unloading and reloading observed in experiments. These models will be formulated by combining rheological elements and energy principles. First, two one-dimensional models independent of the strain rate are formulated, one with one damage variable and the other with two different damage variables in tension and compression, are examined, and using laboratory data, the coefficients of each model are obtained. By comparing the simulation results and laboratory data, the necessary modifications have been made to the models. Finally, by combining the Bresler-Pister anisotropic yield criterion and the one-dimensional model independent of the rate associated with the two damage variables, the corresponding three-dimensional model was obtained. This three-dimensional model was implemented in the form of an explicit finite element method and the result showed acceptable compatibility with the simulation results of the one-dimensional model and experimental data. This three-dimensional model will be suitable for simulating complex geometries. The coefficient of determination for one-dimensional modelsRI ,RI± ,RI , RI±and has been modified and the three-dimensional model has obtained values of 0.882174, 0.965665, 0.995508, 0.996279, and 0.984866, respectively.https://mej.aut.ac.ir/article_4827_5857d68cd9280bc98d079fa912fd6740.pdfAmirkabir University of TechnologyAmirkabir Journal of Mechanical Engineering2008-603254620220823Mixed Finite Element Formulation for 2D Problems Analysis Based on Analytical Solutions of Deferential EquationMixed Finite Element Formulation for 2D Problems Analysis Based on Analytical Solutions of Deferential Equation14431458480710.22060/mej.2022.20650.7287FAMohammadKarkonAssistant Professor, Department of Civil Engineering, Faculty of Engineering, Islamic Azad University, Larestan Branch, Iran.0000-0001-6490-1017MajidYaghoobiAssistant Professor, Civil Engineering and Architectural Department, Faculty of Engineering, University of Torbat Heydarieh, Torbat Heydarieh, Iran.Journal Article20211009<span style="letter-spacing: .05pt;">In this paper, a high-order eight-node element based on the analytical response of the governing differential equation is proposed for the analysis of plane structures.</span> <span style="letter-spacing: .05pt;">The formulation of the proposed element is based on the Hellinger-Reisner mixed functional and the analytical response of the compatibility equation governing plane problems.</span> <span style="letter-spacing: .05pt;">It is worth noting that in order to formulate finite elements with the Hellinger-Reisner functional, two independent stress and displacement fields are required.</span> <span style="letter-spacing: .05pt;">For this purpose, Airy stress functions are first made available by the analytical solution of the compatibility equation.</span> <span style="letter-spacing: .05pt;">By utilizing these stress functions, the stress field within the element is obtained.</span> <span style="letter-spacing: .05pt;">Also, the quadratic displacement field of the isoparametric element is used for intra-element displacement.</span> <span style="letter-spacing: .05pt;">By applying the Hellinger-Reisner mixed functional and stationary of this functional relative to the independent stress and displacement fields, the stiffness matrix, and the element node force vector are made available.</span> <span style="letter-spacing: .05pt;">Finally, with various numerical tests, the accuracy and efficiency of the proposed element are evaluated.</span> <span style="letter-spacing: .05pt;">These tests prove the high accuracy of the proposed element in the analysis of plane structures.</span><span style="letter-spacing: .05pt;">In this paper, a high-order eight-node element based on the analytical response of the governing differential equation is proposed for the analysis of plane structures.</span> <span style="letter-spacing: .05pt;">The formulation of the proposed element is based on the Hellinger-Reisner mixed functional and the analytical response of the compatibility equation governing plane problems.</span> <span style="letter-spacing: .05pt;">It is worth noting that in order to formulate finite elements with the Hellinger-Reisner functional, two independent stress and displacement fields are required.</span> <span style="letter-spacing: .05pt;">For this purpose, Airy stress functions are first made available by the analytical solution of the compatibility equation.</span> <span style="letter-spacing: .05pt;">By utilizing these stress functions, the stress field within the element is obtained.</span> <span style="letter-spacing: .05pt;">Also, the quadratic displacement field of the isoparametric element is used for intra-element displacement.</span> <span style="letter-spacing: .05pt;">By applying the Hellinger-Reisner mixed functional and stationary of this functional relative to the independent stress and displacement fields, the stiffness matrix, and the element node force vector are made available.</span> <span style="letter-spacing: .05pt;">Finally, with various numerical tests, the accuracy and efficiency of the proposed element are evaluated.</span> <span style="letter-spacing: .05pt;">These tests prove the high accuracy of the proposed element in the analysis of plane structures.</span>https://mej.aut.ac.ir/article_4807_f7dafc45da369f8581fdf3bd599075aa.pdf