Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 55 8 2023 10 23 Designing and building a dialogue mechanism suitable for RoboPuppet with using deep inference learning Designing and building a dialogue mechanism suitable for RoboPuppet with using deep inference learning 919 942 5302 10.22060/mej.2023.22001.7553 FA Masoud Amirkhani Department of Mechanical Engineering, University of Isfahan, Isfahan, Iran Hamed Shahbazi Department of Mechanical Engineering, University of Isfahan, Isfahan, Iran Journal Article 2022 12 09 This research endeavors to construct a mechanism, blending text mining and natural language processing, to apply a deep learning dialogue and deep reasoning approach to "Puppet robot." Historically, tent dolls have been an ancient method of interacting with audiences, being directly managed by an operator. With breakthroughs in artificial intelligence and deep learning, it is now possible to reduce the dependence of tent dolls on operators, thereby enabling them to communicate intelligently with audiences. The robot, by identifying the audience's Persian speech, ascertains a fitting answer to their inquiries and broadcasts it in audible Persian. The dialogue mechanism, deeply ingrained in a deep learning algorithm, identifies the user's question and proffers a range of possible answers from the robot's dataset categories. Utilizing the highest probability, the category containing the user's question is identified, and responses to those questions are selected at random. Additionally, the Robo Tent Dialogue mechanism comprises several uncomplicated conditional sections that can furnish suitable responses to repetitive or inappropriate questions. Through diverse training and by altering parameters in the robot's deep learning model, using a 64-class dataset, results reveal that the application of technologically advanced, high-neuron layers outperforms multi-layers without detrimentally impacting the model's final accuracy. This research endeavors to construct a mechanism, blending text mining and natural language processing, to apply a deep learning dialogue and deep reasoning approach to "Puppet robot." Historically, tent dolls have been an ancient method of interacting with audiences, being directly managed by an operator. With breakthroughs in artificial intelligence and deep learning, it is now possible to reduce the dependence of tent dolls on operators, thereby enabling them to communicate intelligently with audiences. The robot, by identifying the audience's Persian speech, ascertains a fitting answer to their inquiries and broadcasts it in audible Persian. The dialogue mechanism, deeply ingrained in a deep learning algorithm, identifies the user's question and proffers a range of possible answers from the robot's dataset categories. Utilizing the highest probability, the category containing the user's question is identified, and responses to those questions are selected at random. Additionally, the Robo Tent Dialogue mechanism comprises several uncomplicated conditional sections that can furnish suitable responses to repetitive or inappropriate questions. Through diverse training and by altering parameters in the robot's deep learning model, using a 64-class dataset, results reveal that the application of technologically advanced, high-neuron layers outperforms multi-layers without detrimentally impacting the model's final accuracy.

https://mej.aut.ac.ir/article_5302_b7046757c3682a28c5bf2024e57678a0.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 55 8 2023 10 23 Singularity, dynamics, and kinetics analysis of a 5 degrees of freedom parallel robot using screw theory Singularity, dynamics, and kinetics analysis of a 5 degrees of freedom parallel robot using screw theory 943 970 5275 10.22060/mej.2023.22216.7580 FA Saeed Khosravi Technology Institute of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran Mechanical Engineering Department, Amirkabir University of Technology, Tehran, Iran Maryam Ghasabzadeh Saryazdi Technology Institute of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran Journal Article 2023 02 20 This paper examines a parallel robot with 5 degrees of freedom with a linear platform. Parallel robots have a restricted workspace, and singularities make the workspace even more confined. So the behavior of the robot in the workplace is examined by focusing on kinematics and dynamics. To do kinematic analysis, the constraint equations are developed using the geometric relations, and the speed and acceleration equations of the robot are derived. The Jacobian matrix is then calculated using the screw theory, and the state of the singularities in the workspace is determined based on the Jacobian matrix. Considering the singularity and physical and geometric limitations, an algorithm for calculating the workspace is presented. In addition, the kinematic index of dexterity is investigated using the Jacobian matrix as a measure of the robot's closeness to the singular configurations. The results of solving kinematic and dynamic problems are validated with the output of the simulation in MATLAB software. This paper examines a parallel robot with 5 degrees of freedom with a linear platform. Parallel robots have a restricted workspace, and singularities make the workspace even more confined. So the behavior of the robot in the workplace is examined by focusing on kinematics and dynamics. To do kinematic analysis, the constraint equations are developed using the geometric relations, and the speed and acceleration equations of the robot are derived. The Jacobian matrix is then calculated using the screw theory, and the state of the singularities in the workspace is determined based on the Jacobian matrix. Considering the singularity and physical and geometric limitations, an algorithm for calculating the workspace is presented. In addition, the kinematic index of dexterity is investigated using the Jacobian matrix as a measure of the robot's closeness to the singular configurations. The results of solving kinematic and dynamic problems are validated with the output of the simulation in MATLAB software.

https://mej.aut.ac.ir/article_5275_5e69fda38cda2060819766569fd93aa5.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 55 8 2023 10 23 Numerical modeling of rock cutting with abrasive waterjet to determine the optimal parameters affecting cutting depth and volume Numerical modeling of rock cutting with abrasive waterjet to determine the optimal parameters affecting cutting depth and volume 971 994 5312 10.22060/mej.2023.22439.7619 FA Satar Mahdevari Department of Mining Engineering, Amirkabir University of Technology, Tehran, Iran 0000-0002-2934-9500 Pedram Bakhtiari HaftLang Department of Mechanical Engineering, Bu-Ali Sina University, Hamedan, Iran Habib Sayehvand Department of Mechanical Engineering, Bu-Ali Sina University, Hamedan, Iran 0000-0003-1554-1128 Journal Article 2023 06 03 In this research, the optimal parameters have been investigated with the aim of increasing the efficiency and improving the quality of rock cutting using an Abrasive Water Jet (AWJ) through the modeling of high-velocity two-phase flow (water and abrasive). The rock-cutting process by AWJ has been simulated using the combined finite element method-smoothed particle hydrodynamics in LS-DYNA software. For this purpose, the effect of parameters of jet velocity, dwell time, changes in volumetric concentration, and changes in the diameter of abrasive particles on the cutting depth and cutting volume of siltstone and shale rock specimens have been investigated. Numerical modeling results showed that with increasing velocity, the cutting depth and cutting volume increased. As the dwell time increases, the energy used by the AWJ to cut the rock increases, which would lead to an increase in the depth and volume of the cut. By increasing the volumetric concentration of abrasive particles up to 3%, the depth and volume of the cut increased with a gentle slope, and after that, no significant improvement was observed. Also, by increasing the diameter of the abrasive particles up to 1.25 mm for siltstone and 1 mm for shale, the depth and volume of the cut increased at first, and after that, they remained constant or decreased. In this research, the optimal parameters have been investigated with the aim of increasing the efficiency and improving the quality of rock cutting using an Abrasive Water Jet (AWJ) through the modeling of high-velocity two-phase flow (water and abrasive). The rock-cutting process by AWJ has been simulated using the combined finite element method-smoothed particle hydrodynamics in LS-DYNA software. For this purpose, the effect of parameters of jet velocity, dwell time, changes in volumetric concentration, and changes in the diameter of abrasive particles on the cutting depth and cutting volume of siltstone and shale rock specimens have been investigated. Numerical modeling results showed that with increasing velocity, the cutting depth and cutting volume increased. As the dwell time increases, the energy used by the AWJ to cut the rock increases, which would lead to an increase in the depth and volume of the cut. By increasing the volumetric concentration of abrasive particles up to 3%, the depth and volume of the cut increased with a gentle slope, and after that, no significant improvement was observed. Also, by increasing the diameter of the abrasive particles up to 1.25 mm for siltstone and 1 mm for shale, the depth and volume of the cut increased at first, and after that, they remained constant or decreased.

https://mej.aut.ac.ir/article_5312_5e0f17d9e09d1881692cf84a3b869f75.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 55 8 2023 10 23 Numerical and Empirical Investigation on Bending Behavior of Composite Bipolar Plates for Polymer Electrolyte Membrane Fuel Cells Numerical and Empirical Investigation on Bending Behavior of Composite Bipolar Plates for Polymer Electrolyte Membrane Fuel Cells 995 1008 5276 10.22060/mej.2023.21720.7495 FA Leyla Emami Faculty of Martial and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran, Iran Mohammad Mahdi Barzegari Northern Research center for science & Technology, Malek Ashtar University of Technology, Fereydunkenar, Iran Mohammad Reza Zamani Faculty of Martial and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran, Iran Journal Article 2022 08 24 Polymer electrolyte membrane fuel cells, as an energy generator, convert the chemical energy of the fuel directly into electrical energy. An important component of polymer fuel cells is bipolar plates, which are responsible for the distribution of fuel and oxidants and facilitate the management of water inside the cell and the transmission of electric current. In this study, the fracture method of graphite-based composite bipolar plates of polymer fuel cells under bending loads was investigated experimentally and numerically. Simple and perforated composite bipolar plates were tested and simulated with the approach of determining flexural stability under static load. In numerical analysis, mechanical simulation using the finite element method and Abaqus software were used. Then, after making the laboratory samples, the experimental test of three-point bending was performed on them to validate the simulation results. Finally, the results of numerical and experimental analyses of the flexural behavior of composite bipolar plates were compared with each other. A comparison of the results of numerical and experimental analyses showed that the results of these two methods had an acceptable agreement with each other. In addition, the presence of a high percentage of graphite as well as high fragility weakens the body, and beams of this material increase the specimen of the sample, which occurs only due to the molecular bond of graphite, which causes the graphite to slip. Polymer electrolyte membrane fuel cells, as an energy generator, convert the chemical energy of the fuel directly into electrical energy. An important component of polymer fuel cells is bipolar plates, which are responsible for the distribution of fuel and oxidants and facilitate the management of water inside the cell and the transmission of electric current. In this study, the fracture method of graphite-based composite bipolar plates of polymer fuel cells under bending loads was investigated experimentally and numerically. Simple and perforated composite bipolar plates were tested and simulated with the approach of determining flexural stability under static load. In numerical analysis, mechanical simulation using the finite element method and Abaqus software were used. Then, after making the laboratory samples, the experimental test of three-point bending was performed on them to validate the simulation results. Finally, the results of numerical and experimental analyses of the flexural behavior of composite bipolar plates were compared with each other. A comparison of the results of numerical and experimental analyses showed that the results of these two methods had an acceptable agreement with each other. In addition, the presence of a high percentage of graphite as well as high fragility weakens the body, and beams of this material increase the specimen of the sample, which occurs only due to the molecular bond of graphite, which causes the graphite to slip.

https://mej.aut.ac.ir/article_5276_ed383ec94720d62a939bfb6bdd98f50c.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 55 8 2023 10 23 Finite Element Simulation and Experimental Verification of HAZ Softening during Welding of Aluminum alloy 7075 Finite Element Simulation and Experimental Verification of HAZ Softening during Welding of Aluminum alloy 7075 1009 1020 5272 10.22060/mej.2023.21436.7582 FA Mohammad Javad Pirbarjasteh Department of Maritime Engineering, Amirkabir University of Technology, Tehran, Iran Mahdi Iranmanesh Department of Maritime Engineering, Amirkabir University of Technology, Tehran, Iran Eslam Ranjbarnodeh Department of Materials and Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran 0000-0002-6958-7044 Emad Cheraghi Rizi Department of Materials and Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran Journal Article 2023 02 25 The one-of-a-kind properties of series 7xxx aluminum alloys such as high strength, relatively low density, good formability, and good resistance to stress corrosion cracking have made this class of materials a good choice for aerospace, automobile, and marine industries. Watertight, low weight, and fast procedure are the reasons why welding is used in many industries. The heat that welding produces causes many problems like softening in the heat-affected zone. In this research with the use of a 3-D finite element model, the heat transfer of the Al-7075-T6 is investigated and verified by comparing them with the experimental model, and the reduction of hardness in the heat-affected zone of the aluminum was predicted with good precision. In the next step, the softening of HAZ due to welding was measured with microhardness. With the use of the FEM model kinetic of over-aging was measured. The results show hardness of the alloy has two sources i.e., age-hardening and work-hardening. It seems welding eliminates the effects of age-hardening but has no effect on the hardness that comes from work hardening. Also, the decrease in the hardness of the solution-annealed area can be recovered through proper heat treatment. However, it is unrecoverable in the over-aged area. The one-of-a-kind properties of series 7xxx aluminum alloys such as high strength, relatively low density, good formability, and good resistance to stress corrosion cracking have made this class of materials a good choice for aerospace, automobile, and marine industries. Watertight, low weight, and fast procedure are the reasons why welding is used in many industries. The heat that welding produces causes many problems like softening in the heat-affected zone. In this research with the use of a 3-D finite element model, the heat transfer of the Al-7075-T6 is investigated and verified by comparing them with the experimental model, and the reduction of hardness in the heat-affected zone of the aluminum was predicted with good precision. In the next step, the softening of HAZ due to welding was measured with microhardness. With the use of the FEM model kinetic of over-aging was measured. The results show hardness of the alloy has two sources i.e., age-hardening and work-hardening. It seems welding eliminates the effects of age-hardening but has no effect on the hardness that comes from work hardening. Also, the decrease in the hardness of the solution-annealed area can be recovered through proper heat treatment. However, it is unrecoverable in the over-aged area.

https://mej.aut.ac.ir/article_5272_e8855b3528cb03d1def9803220bd3cb9.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 55 8 2023 10 23 Modeling and Analysis of the Bending Behavior of Soft Pneumatic Network Actuator with Hyperelastic Models Modeling and Analysis of the Bending Behavior of Soft Pneumatic Network Actuator with Hyperelastic Models 1021 1042 5311 10.22060/mej.2023.22104.7567 FA Sina Esmalipour Department of Mechanical Engineering, Faculty of Engineering ٍ University of Mohaghegh Ardabili, Ardabil, Iran Masoud Ajri Department of Mechanical Engineering, Faculty of Engineering ٍ University of Mohaghegh Ardabili, Ardabil, Iran Journal Article 2023 01 14 Soft robots made of hyperelastic materials are widely used in medicine. Designing and analyzing the behavior of soft actuators is challenging due to the nonlinear nature of hyperelastic materials. This study examines the effects of geometrical parameters including the wall thickness, the distance between the chambers, the layer’s thickness, the side walls thickness, the cross-section shape, the material of the actuator on the bending behavior, the created stresses in the inner walls and the resulting tip force to obtain the optimal geometry and material to create the maximum bending angle and tip force of the actuator. For modeling the common materials behavior of soft actuators such as Dragon Skin 30, TPU, Ecoflex30, and RTV2, five Hyperelastic model predictions are compared with the uniaxial stress-strain test on these materials, and the best model is selected to simulate each material. The results show that, by reducing the thickness of the walls, the distance between the chambers, and the lower layer’s thickness, and using the square cross-section with RTV2, the actuator's maximum bending angle was achieved. However, by increasing the thickness of the walls, the number of chambers, and the thickness of the lower layers, and using DS30, the maximum tip force was achieved. Soft robots made of hyperelastic materials are widely used in medicine. Designing and analyzing the behavior of soft actuators is challenging due to the nonlinear nature of hyperelastic materials. This study examines the effects of geometrical parameters including the wall thickness, the distance between the chambers, the layer’s thickness, the side walls thickness, the cross-section shape, the material of the actuator on the bending behavior, the created stresses in the inner walls and the resulting tip force to obtain the optimal geometry and material to create the maximum bending angle and tip force of the actuator. For modeling the common materials behavior of soft actuators such as Dragon Skin 30, TPU, Ecoflex30, and RTV2, five Hyperelastic model predictions are compared with the uniaxial stress-strain test on these materials, and the best model is selected to simulate each material. The results show that, by reducing the thickness of the walls, the distance between the chambers, and the lower layer’s thickness, and using the square cross-section with RTV2, the actuator's maximum bending angle was achieved. However, by increasing the thickness of the walls, the number of chambers, and the thickness of the lower layers, and using DS30, the maximum tip force was achieved.

https://mej.aut.ac.ir/article_5311_be3b0b544433b768685e3436621590ff.pdf