Author Center
Editor Work
Peer Review
Editorial Entry
Email Alert
RSS2022 Vol. 41, No. 9
Display Method:
2022, 41(9): 1313-1320.
doi: 10.13433/j.cnki.1003-8728.20200515
PDF 2563KB
Abstract:
The aim of this study is to explore the influence rule of temperature effect on the dynamics properties of magnetorheological damper (MRD). Based on the Bingham mechanical model and the principle of magnetic circuit equivalent, a parametric model of the MRD prototype is established, and ANSYS is utilized to simulate and research influence mechanism and rule of temperature on damping force characteristics, adjustable damping force coefficient and response time. A temperature-dynamics measurement and control test platform for MRD was built. We have carried out experiments on the influence of temperature effect on MRD dynamic performance under different input currents, excitation frequencies and amplitudes, and analyzed the dynamic changes of damping force-displacement characteristics, adjustable coefficients and response time. The result shows that the influence of temperature on the damping force and response time is negatively correlated, and the influence of temperature on the adjustable coefficient is positively correlated. The results of simulation and experiment are well consistent. The results have reference value for the temperature compensation design and performance optimization of MRD.
The aim of this study is to explore the influence rule of temperature effect on the dynamics properties of magnetorheological damper (MRD). Based on the Bingham mechanical model and the principle of magnetic circuit equivalent, a parametric model of the MRD prototype is established, and ANSYS is utilized to simulate and research influence mechanism and rule of temperature on damping force characteristics, adjustable damping force coefficient and response time. A temperature-dynamics measurement and control test platform for MRD was built. We have carried out experiments on the influence of temperature effect on MRD dynamic performance under different input currents, excitation frequencies and amplitudes, and analyzed the dynamic changes of damping force-displacement characteristics, adjustable coefficients and response time. The result shows that the influence of temperature on the damping force and response time is negatively correlated, and the influence of temperature on the adjustable coefficient is positively correlated. The results of simulation and experiment are well consistent. The results have reference value for the temperature compensation design and performance optimization of MRD.
2022, 41(9): 1321-1326.
doi: 10.13433/j.cnki.1003-8728.20200494
Abstract:
In order to study the characteristics of the hydraulic hydrogen injection system matching with the direct injection hydrogen engine, the simulation model for the hydraulic hydrogen injection system of the in cylinder direct injection hydrogen engine is established via AMESim software. The dynamic process of the hydrogen injection system is simulated and analyzed with the present model. Single factor analysis method was used to study the influence of the hydraulic pipeline structure parameters, absolute viscosity and supply pressure of hydraulic oil, preload and stiffness of return spring on response delay of needle valve in hydrogen injection system. It is finally decided to select the structure parameters of hydrogen injection system matching the in cylinder direct injection hydrogen engine, including preload of return spring 210 N, spring stiffness 190 N/mm, oil supply pressure 10 MPa, diameter of hydraulic pipe 4 mm and absolute viscosity of hydraulic oil 51 cp. It provides a reference for designing the electronic hydraulic hydrogen injection system.
In order to study the characteristics of the hydraulic hydrogen injection system matching with the direct injection hydrogen engine, the simulation model for the hydraulic hydrogen injection system of the in cylinder direct injection hydrogen engine is established via AMESim software. The dynamic process of the hydrogen injection system is simulated and analyzed with the present model. Single factor analysis method was used to study the influence of the hydraulic pipeline structure parameters, absolute viscosity and supply pressure of hydraulic oil, preload and stiffness of return spring on response delay of needle valve in hydrogen injection system. It is finally decided to select the structure parameters of hydrogen injection system matching the in cylinder direct injection hydrogen engine, including preload of return spring 210 N, spring stiffness 190 N/mm, oil supply pressure 10 MPa, diameter of hydraulic pipe 4 mm and absolute viscosity of hydraulic oil 51 cp. It provides a reference for designing the electronic hydraulic hydrogen injection system.
2022, 41(9): 1327-1333.
doi: 10.13433/j.cnki.1003-8728.20200485
Abstract:
The brushless DC motor (BLDCM) is widely used in an electronic hydraulic braking system (EHB), but its cogging torque affects its servo control quality, thereby hindering the improvement of the EHB's comprehensive performance. For this reason, the research on thecurrentcompensation control strategy for reducing the cogging torque of the BLDCM in the EHB is carried out in this paper. Firstly, the cogging torque variation law is obtainedwith the analytical method and the finite element method. Secondly, based on the mapping relationship between cogging torque and rotor position, a control strategy for the real-time current compensation of the cogging torque based on the motor position signal is proposed. Finally, the control model and the finite element model of the BLDCM are built and their simulations are jointly conducted. The research results show that after the current compensation control strategy is used, the motor speed and torque fluctuation are significantly reduced, the position servo accuracy is improved, and the influence of cogging torque on the quality of motor servo control is effectively suppressed.
The brushless DC motor (BLDCM) is widely used in an electronic hydraulic braking system (EHB), but its cogging torque affects its servo control quality, thereby hindering the improvement of the EHB's comprehensive performance. For this reason, the research on thecurrentcompensation control strategy for reducing the cogging torque of the BLDCM in the EHB is carried out in this paper. Firstly, the cogging torque variation law is obtainedwith the analytical method and the finite element method. Secondly, based on the mapping relationship between cogging torque and rotor position, a control strategy for the real-time current compensation of the cogging torque based on the motor position signal is proposed. Finally, the control model and the finite element model of the BLDCM are built and their simulations are jointly conducted. The research results show that after the current compensation control strategy is used, the motor speed and torque fluctuation are significantly reduced, the position servo accuracy is improved, and the influence of cogging torque on the quality of motor servo control is effectively suppressed.
2022, 41(9): 1334-1339.
doi: 10.13433/j.cnki.1003-8728.20200503
Abstract:
In this paper, a flexible bending joint is designed, which is composed of aluminum alloy ring, superelastic shape memory alloy (SMA) and two-way shape memory alloy wire. The superelastic SMA is used as the supporting rod and the two-way SMA wire is used as the driving mechanism. The flexible joint can be bent autonomously by current driving the two-way SMA to contract. After the current is unloaded, the joint can return to the initial state. The simulationmodel via ABAQUS at a current of 2.1 A and shrinkage rate of 4.02% is established. The 3D kinematic model for the bending joint is established, and the theoretical values of the bending angles of the two joints under different loading conditions are obtained. By comparing the simulated results via the present model with the experimental, the results show that superelastic SMA can effectively increase the bending angle, and the maximum bending angle of the two joints is 43.1° and 22° respectively.
In this paper, a flexible bending joint is designed, which is composed of aluminum alloy ring, superelastic shape memory alloy (SMA) and two-way shape memory alloy wire. The superelastic SMA is used as the supporting rod and the two-way SMA wire is used as the driving mechanism. The flexible joint can be bent autonomously by current driving the two-way SMA to contract. After the current is unloaded, the joint can return to the initial state. The simulationmodel via ABAQUS at a current of 2.1 A and shrinkage rate of 4.02% is established. The 3D kinematic model for the bending joint is established, and the theoretical values of the bending angles of the two joints under different loading conditions are obtained. By comparing the simulated results via the present model with the experimental, the results show that superelastic SMA can effectively increase the bending angle, and the maximum bending angle of the two joints is 43.1° and 22° respectively.
2022, 41(9): 1340-1345.
doi: 10.13433/j.cnki.1003-8728.20200504
Abstract:
n order to obtain process volatility and the best process parameters of ultrasonic impact 45 steel surface integrity, the ultrasonic impact orthogonal test was carried out on the surface of 45 steel. The signal-to-noise ratio (SNR) method is used to analyze the influence of rotational speed, feeding speed and interference on surface integrity (surface roughness, hardness and residual stress). The multi-objective parameter optimization was carried out by combining grey relational degree (GRD), and the optimal process parameter combination of ultrasonic impact 45 steel surface integrity is obtained. The experimental results show that: the importance of process parameters on surface integrity are as follows: rotational speed, interference, feed speed; the optimal process parameters are rotational speed 45 r/min, feed speed 0.18 mm/r and interference 0.025 mm. It is found that the optimized parameters can significantly reduce the surface roughness, improve the surface hardness and surface residual compressive stress, which further proves the reliability of the optimized parameters.
n order to obtain process volatility and the best process parameters of ultrasonic impact 45 steel surface integrity, the ultrasonic impact orthogonal test was carried out on the surface of 45 steel. The signal-to-noise ratio (SNR) method is used to analyze the influence of rotational speed, feeding speed and interference on surface integrity (surface roughness, hardness and residual stress). The multi-objective parameter optimization was carried out by combining grey relational degree (GRD), and the optimal process parameter combination of ultrasonic impact 45 steel surface integrity is obtained. The experimental results show that: the importance of process parameters on surface integrity are as follows: rotational speed, interference, feed speed; the optimal process parameters are rotational speed 45 r/min, feed speed 0.18 mm/r and interference 0.025 mm. It is found that the optimized parameters can significantly reduce the surface roughness, improve the surface hardness and surface residual compressive stress, which further proves the reliability of the optimized parameters.
2022, 41(9): 1346-1351.
doi: 10.13433/j.cnki.1003-8728.20200505
Abstract:
In the current research center, the soft actuator is generally controlled with the pneumatic method, which has the advantage of ductility. With the improvement and promotion of this advantage, the authors have developed a new soft actuator composed of a variety of soft composites by imitating the characteristics of a multi-jointfinger-like structure. The radial driving force of the driving part is improved by the circumferential binding of the fine line wound around the cavity. Therefore, on the premise of maintaining the original softness, the clamping performance is improved by improving the bending angle of the main part. The D-H kinematics model is established toaccuratelycalculate the pose of the structure. Finally, the bending angle of each joint and the clamping performance of the mechanism are measured by experiments, which prove that the structural design can be widely used in practical application.
In the current research center, the soft actuator is generally controlled with the pneumatic method, which has the advantage of ductility. With the improvement and promotion of this advantage, the authors have developed a new soft actuator composed of a variety of soft composites by imitating the characteristics of a multi-jointfinger-like structure. The radial driving force of the driving part is improved by the circumferential binding of the fine line wound around the cavity. Therefore, on the premise of maintaining the original softness, the clamping performance is improved by improving the bending angle of the main part. The D-H kinematics model is established toaccuratelycalculate the pose of the structure. Finally, the bending angle of each joint and the clamping performance of the mechanism are measured by experiments, which prove that the structural design can be widely used in practical application.
2022, 41(9): 1352-1361.
doi: 10.13433/j.cnki.1003-8728.20200497
Abstract:
In order to achieve the flexible movement of wheeled mobile robot and improve its environmental adaptability, a new mobile chassis structure is proposed in this paper. The dual power differential system is used to accomplish power distribution under different modes. A special structure is used to complete the four-wheel independent steering, which makes the chassis steering easier and realizes the pure rolling in the steering process. The balance rocker arm adjusting mechanism is used to adjust the movement of the chassis swing arms and the body, and self-adaptive to the undulating road surface is realized with the rotation of swing arms, so as to enhance the ability of the chassis to surmount obstacles. The work principle of the mobile chassis is analyzed, and the corresponding control strategy is designed. On this basis, the deviation coupling control module is added to improve the synchronous coordination performance of multi motor steering. The effect of the control module is verified by MATLAB simulation, and the experimental prototype and control system are built and tested. The test results show that the mobile chassis structure principle proposed in this paper is correct and feasible, the chassis has strong obstacle crossing ability and strong adaptability in the field environment.
In order to achieve the flexible movement of wheeled mobile robot and improve its environmental adaptability, a new mobile chassis structure is proposed in this paper. The dual power differential system is used to accomplish power distribution under different modes. A special structure is used to complete the four-wheel independent steering, which makes the chassis steering easier and realizes the pure rolling in the steering process. The balance rocker arm adjusting mechanism is used to adjust the movement of the chassis swing arms and the body, and self-adaptive to the undulating road surface is realized with the rotation of swing arms, so as to enhance the ability of the chassis to surmount obstacles. The work principle of the mobile chassis is analyzed, and the corresponding control strategy is designed. On this basis, the deviation coupling control module is added to improve the synchronous coordination performance of multi motor steering. The effect of the control module is verified by MATLAB simulation, and the experimental prototype and control system are built and tested. The test results show that the mobile chassis structure principle proposed in this paper is correct and feasible, the chassis has strong obstacle crossing ability and strong adaptability in the field environment.
2022, 41(9): 1362-1368.
doi: 10.13433/j.cnki.1003-8728.20200524
Abstract:
In view of the influence of the working pressure and hydraulic resistance coefficient of the hydraulic cylinder on the working effect of the dynamic stability device, the wheel rail contact characteristics, the working principle of the hydraulic cylinder and the stress characteristics of the rail are studied in detail. Based on the bond graph model of rigid rail dynamic stabilizer track lateral coupling system, a new bond graph model of flexible rail dynamic stabilizer track lateral coupling system based on Euler beam theory is proposed. Based on this new model, the vibration characteristics of sleepers are analyzed, and the accuracy of the model is verified by comparing the analysis results with the experimental results. The influence of working pressure of clamp cylinder, hydraulic resistance parameters of inlet and outlet of hydraulic cylinder and wheel rail contact angle on energy transfer efficiency and operation effect between wheel and rail are analyzed. The results show that when the efficiency of energy transfer between wheel and rail is above 95%, the angle between wheel and rail should be kept between 0 and 40°; when the clearance between wheel and rail is eliminated (that is, when the working pressure of clamp cylinder is 7 MPa), the energy transfer efficiency between wheel and rail will increase from 30% to 99%, which is increased by 69%.
In view of the influence of the working pressure and hydraulic resistance coefficient of the hydraulic cylinder on the working effect of the dynamic stability device, the wheel rail contact characteristics, the working principle of the hydraulic cylinder and the stress characteristics of the rail are studied in detail. Based on the bond graph model of rigid rail dynamic stabilizer track lateral coupling system, a new bond graph model of flexible rail dynamic stabilizer track lateral coupling system based on Euler beam theory is proposed. Based on this new model, the vibration characteristics of sleepers are analyzed, and the accuracy of the model is verified by comparing the analysis results with the experimental results. The influence of working pressure of clamp cylinder, hydraulic resistance parameters of inlet and outlet of hydraulic cylinder and wheel rail contact angle on energy transfer efficiency and operation effect between wheel and rail are analyzed. The results show that when the efficiency of energy transfer between wheel and rail is above 95%, the angle between wheel and rail should be kept between 0 and 40°; when the clearance between wheel and rail is eliminated (that is, when the working pressure of clamp cylinder is 7 MPa), the energy transfer efficiency between wheel and rail will increase from 30% to 99%, which is increased by 69%.
2022, 41(9): 1369-1375.
doi: 10.13433/j.cnki.1003-8728.20220188
Abstract:
To comprehensively consider the effects of hinge friction, cable tensions and flexibility of the driving-cable on the deployment process of ring truss mesh deployable antennas, a dynamic model of ring truss antenna system including driving-cable and pulley was established. The deployment strategy based on position control was used to plan the deployment process of the antenna, through which the peak of deployment angular acceleration was minimized and the optimal input trajectory of the driving-cable was obtained. With the dynamic model of the driving-cable being established using the bushing force method and the cable tensions being equivalent to time-varying external loads acting on the truss hinges, the dynamic model of the overall antenna system was obtained. Simulation results show that the parameters such as the flexibility of driving-cable and the deployment time will have a significant impact on the deployment angular acceleration and driving-cable force in the deployment process.
To comprehensively consider the effects of hinge friction, cable tensions and flexibility of the driving-cable on the deployment process of ring truss mesh deployable antennas, a dynamic model of ring truss antenna system including driving-cable and pulley was established. The deployment strategy based on position control was used to plan the deployment process of the antenna, through which the peak of deployment angular acceleration was minimized and the optimal input trajectory of the driving-cable was obtained. With the dynamic model of the driving-cable being established using the bushing force method and the cable tensions being equivalent to time-varying external loads acting on the truss hinges, the dynamic model of the overall antenna system was obtained. Simulation results show that the parameters such as the flexibility of driving-cable and the deployment time will have a significant impact on the deployment angular acceleration and driving-cable force in the deployment process.
2022, 41(9): 1376-1380.
doi: 10.13433/j.cnki.1003-8728.20200476
Abstract:
In order to study the gas-liquid two-phase distribution and the torque characteristics of the torque limited hydrodynamic coupling, the YOX500 torque limited hydrodynamic coupling is used as the analysis model. The VOF two-phase flow model, the realizable k-ε turbulence model and the PISO algorithm are used to perform the transient simulations of the internal flow field of the hydrodynamiccoupling under different filling rates and different working conditions. The results show that as the speed ratio decreases, the internal circulation of the hydrodynamiccoupling gradually changes from a small circulation to a large one. Under the condition of 80% filling rate, the gas-liquid two-phase distribution to the suction surface and pressure surface of the impeller blade is basically consistent with the experimental results, thus proving the effectiveness of the method. At a high-speed ratio, the torque characteristics are consistent with the experimental results. At a low speed ratio, the error is large; therefore the method is no longer applicable.
In order to study the gas-liquid two-phase distribution and the torque characteristics of the torque limited hydrodynamic coupling, the YOX500 torque limited hydrodynamic coupling is used as the analysis model. The VOF two-phase flow model, the realizable k-ε turbulence model and the PISO algorithm are used to perform the transient simulations of the internal flow field of the hydrodynamiccoupling under different filling rates and different working conditions. The results show that as the speed ratio decreases, the internal circulation of the hydrodynamiccoupling gradually changes from a small circulation to a large one. Under the condition of 80% filling rate, the gas-liquid two-phase distribution to the suction surface and pressure surface of the impeller blade is basically consistent with the experimental results, thus proving the effectiveness of the method. At a high-speed ratio, the torque characteristics are consistent with the experimental results. At a low speed ratio, the error is large; therefore the method is no longer applicable.
2022, 41(9): 1381-1386.
doi: 10.13433/j.cnki.1003-8728.20200475
Abstract:
In order to improve the tracking accuracy of the welding seam of the double metal saw blade laser welding machine, the welding seam tracking control model for the double metal saw blade laser welding machine was established. The method based on adaptive region of interest (ROI) is used to preprocess the weld track image, and the center line of weld track is obtained by using the horizontal projection method. According to the characteristics of laser stripe discontinuity at the weld position, the characteristic information of weld can be obtained by using the scanning the center line of laser stripe, thus the weld track can be determined. Considering the nonholonomic constraints, the dynamic model for the laser welding machine of bimetal saw blade is described by using Lagrange dynamics method. Based on the dynamic model, different seam tracking control strategies are formulated according to the correlation between the distance between the welding gun and the center line of the weld track and the limit length of the transverse slider in the tracking process. The inertia and workpiece table of the laser welding machine for bimetal saw blade are considered. The sliding mode variable structure control model is designed based on the dynamics of mobile welding robot and the coordinated control of cross slider. The test results show that under the control of the model, the tracking results of the welding seam track of the research object basically coincide with the actual track.
In order to improve the tracking accuracy of the welding seam of the double metal saw blade laser welding machine, the welding seam tracking control model for the double metal saw blade laser welding machine was established. The method based on adaptive region of interest (ROI) is used to preprocess the weld track image, and the center line of weld track is obtained by using the horizontal projection method. According to the characteristics of laser stripe discontinuity at the weld position, the characteristic information of weld can be obtained by using the scanning the center line of laser stripe, thus the weld track can be determined. Considering the nonholonomic constraints, the dynamic model for the laser welding machine of bimetal saw blade is described by using Lagrange dynamics method. Based on the dynamic model, different seam tracking control strategies are formulated according to the correlation between the distance between the welding gun and the center line of the weld track and the limit length of the transverse slider in the tracking process. The inertia and workpiece table of the laser welding machine for bimetal saw blade are considered. The sliding mode variable structure control model is designed based on the dynamics of mobile welding robot and the coordinated control of cross slider. The test results show that under the control of the model, the tracking results of the welding seam track of the research object basically coincide with the actual track.
2022, 41(9): 1387-1393.
doi: 10.13433/j.cnki.1003-8728.20200495
Abstract:
In order to improve the prediction ability of shaving tooth profile concave error, a multi-source coupled error prediction model was proposed by taking the axial gear shaving method as the example. In the present model, some factors such as shaving tooth contact ratio and machine tool movement are coupled while considering the installation error. Firstly, a gear shaving analysis model with axial angle error, center distance error and high speed axis synchronization error is established. Then, based on the principle of shaving, multi-source factors affecting the shaving processing are coupled into a single cutting area of the meshing point, and a prediction model for the concave error of the shaving tooth profile is built on the basis of the genetic algorithm BP neural network (GA-BP). The paper reveals the influence of the single cutting area of the meshing point on the concave error of the tooth profile, and realizes the quantitative prediction and mechanism research of the multi-source factor coupling of the concave error of the shaving tooth profile. The experimental results show that, considering the installation error, the single cutting area of the tooth shaving mesh point is too large, which is the main cause of the concave error of the shaving tooth profile.
In order to improve the prediction ability of shaving tooth profile concave error, a multi-source coupled error prediction model was proposed by taking the axial gear shaving method as the example. In the present model, some factors such as shaving tooth contact ratio and machine tool movement are coupled while considering the installation error. Firstly, a gear shaving analysis model with axial angle error, center distance error and high speed axis synchronization error is established. Then, based on the principle of shaving, multi-source factors affecting the shaving processing are coupled into a single cutting area of the meshing point, and a prediction model for the concave error of the shaving tooth profile is built on the basis of the genetic algorithm BP neural network (GA-BP). The paper reveals the influence of the single cutting area of the meshing point on the concave error of the tooth profile, and realizes the quantitative prediction and mechanism research of the multi-source factor coupling of the concave error of the shaving tooth profile. The experimental results show that, considering the installation error, the single cutting area of the tooth shaving mesh point is too large, which is the main cause of the concave error of the shaving tooth profile.
2022, 41(9): 1394-1402.
doi: 10.13433/j.cnki.1003-8728.20220143
Abstract:
Based on the idea of quasi-physical algorithm and performance analysis, a high-performance heuristic algorithm for solving the unequal circle packing problem is proposed in this study. The new algorithm is based on a fixed-step sequence gradient descent quasi-physical algorithm, and it uses relative potential energy as the constraint function of the layout to eliminate the influence of graph size, and also uses the adjacency matrix acceleration method with variable adjacency coefficient to improve the computational efficiency. In the optimization strategy, an improved branch search method is proposed to extend the branch length to expand the search range and realize the expansion of the survival of the fittest strategy. In the later stage of the iteration, multiple simulated annealing calculations are performed through the domain operator to increase the diversity of solutions and avoid local optimum. A large number of experiments on containers with different shapes and international open examples show that the new algorithm is more efficient and stable for unequal circle packing problem.
Based on the idea of quasi-physical algorithm and performance analysis, a high-performance heuristic algorithm for solving the unequal circle packing problem is proposed in this study. The new algorithm is based on a fixed-step sequence gradient descent quasi-physical algorithm, and it uses relative potential energy as the constraint function of the layout to eliminate the influence of graph size, and also uses the adjacency matrix acceleration method with variable adjacency coefficient to improve the computational efficiency. In the optimization strategy, an improved branch search method is proposed to extend the branch length to expand the search range and realize the expansion of the survival of the fittest strategy. In the later stage of the iteration, multiple simulated annealing calculations are performed through the domain operator to increase the diversity of solutions and avoid local optimum. A large number of experiments on containers with different shapes and international open examples show that the new algorithm is more efficient and stable for unequal circle packing problem.
2022, 41(9): 1403-1408.
doi: 10.13433/j.cnki.1003-8728.20200490
Abstract:
Taking a domestic motorized spindle as an object, the secondary finite element modeling of the model was carried out through SolidWorks, and then imported into the Workbench to be parameterized. On the basis of static and modal analysis, taking the span of front and rear bearing group, overhanging amount, front radius of spindle and inner hole radius of front end of motorized spindle as design variables, the sensitivity analysis of design parameters is carried out with minimum total deformation, maximum first natural frequency and lightest geometry mass as optimization objectives, and then response surface optimization model is established and optimized. The optimization results of motorized spindle show that the static stiffness increases by 4.2%, the first natural frequency increases by 7.4%, and the mass decreases by 5.3%, these improve mechanic performances of motorized spindle.
Taking a domestic motorized spindle as an object, the secondary finite element modeling of the model was carried out through SolidWorks, and then imported into the Workbench to be parameterized. On the basis of static and modal analysis, taking the span of front and rear bearing group, overhanging amount, front radius of spindle and inner hole radius of front end of motorized spindle as design variables, the sensitivity analysis of design parameters is carried out with minimum total deformation, maximum first natural frequency and lightest geometry mass as optimization objectives, and then response surface optimization model is established and optimized. The optimization results of motorized spindle show that the static stiffness increases by 4.2%, the first natural frequency increases by 7.4%, and the mass decreases by 5.3%, these improve mechanic performances of motorized spindle.
2022, 41(9): 1409-1413.
doi: 10.13433/j.cnki.1003-8728.20220149
Abstract:
In this paper, the effects of the different welding methods, contact configuration and thickness differences on the formability (Limiting dome height, LDH) value of aluminum alloy tailor welded blanks were studied, and the three influencing factors were analyzed with Taguchi method. For the aluminum alloy tailor welded blanks with different thickness: the LDH of Face configuration is less than that of Root configuration, and has nothing to do with the welding method; the LDH of laser welding is less than that of friction stir welding and has nothing to do with the configuration. For the aluminum alloy tailor welded blanks with the same thickness: the LDH is higher than that of the different thickness, regardless of the configuration; the LDH in Face configuration is still smaller than that in Root configuration. The results show that the thickness difference is the most important factor affecting the LDH value, the contact configuration has slight influence on the LDH value, and the welding method has the least influence on the LDH value.
In this paper, the effects of the different welding methods, contact configuration and thickness differences on the formability (Limiting dome height, LDH) value of aluminum alloy tailor welded blanks were studied, and the three influencing factors were analyzed with Taguchi method. For the aluminum alloy tailor welded blanks with different thickness: the LDH of Face configuration is less than that of Root configuration, and has nothing to do with the welding method; the LDH of laser welding is less than that of friction stir welding and has nothing to do with the configuration. For the aluminum alloy tailor welded blanks with the same thickness: the LDH is higher than that of the different thickness, regardless of the configuration; the LDH in Face configuration is still smaller than that in Root configuration. The results show that the thickness difference is the most important factor affecting the LDH value, the contact configuration has slight influence on the LDH value, and the welding method has the least influence on the LDH value.
2022, 41(9): 1414-1419.
doi: 10.13433/j.cnki.1003-8728.20200487
Abstract:
A numerical model for shot peening of TC4 alloy was established based on the finite element method. Firstly, the finite element for shot peening of TC4 alloy established based on the software of ABAQUS was used to simulate the shot peening speeds of 40, 60, 80, 100 m/s. The results showed that the thickness of the surface residual stress, the maximum residual compressive stress and residual compressive stress layers increasegradually with the increasing of shot peening speed. Secondly, the finite element simulations of shot peening processes were carried out for normal incidence, incidence angle of 10° and incidence angle of 20°. The results showed that with the increasing of incidence angle, the surface roughness of the target would change slightly, but the influence on the residual compressive stress cannot be ignored, which can be explained by that the gradual decrease of the maximum residual stress from 607.3 MPa to 504.4 MPa, a decrease of 20.4%, and the thickness of the residual compressive stress layer from 158.5 μm to 145.2 μm, a decrease of 8.4%. In order to achieve the best shot peening strength and effect, it is suggested to control the incident angle between 0 and 10°.
A numerical model for shot peening of TC4 alloy was established based on the finite element method. Firstly, the finite element for shot peening of TC4 alloy established based on the software of ABAQUS was used to simulate the shot peening speeds of 40, 60, 80, 100 m/s. The results showed that the thickness of the surface residual stress, the maximum residual compressive stress and residual compressive stress layers increasegradually with the increasing of shot peening speed. Secondly, the finite element simulations of shot peening processes were carried out for normal incidence, incidence angle of 10° and incidence angle of 20°. The results showed that with the increasing of incidence angle, the surface roughness of the target would change slightly, but the influence on the residual compressive stress cannot be ignored, which can be explained by that the gradual decrease of the maximum residual stress from 607.3 MPa to 504.4 MPa, a decrease of 20.4%, and the thickness of the residual compressive stress layer from 158.5 μm to 145.2 μm, a decrease of 8.4%. In order to achieve the best shot peening strength and effect, it is suggested to control the incident angle between 0 and 10°.
2022, 41(9): 1420-1427.
doi: 10.13433/j.cnki.1003-8728.20200478
Abstract:
For recognition and classificationof metal defect, traditional machine learning requires manual feature extraction while deep learning requires a large number of samples. This paper proposes a classification method of metal defectbased on the shallow convolutional neural network (CNN) and decision tree (DT) for small and medium-sized defect data sets. The feature is extracted by the convolutional neural network, and the defect is classified with the decision tree. The principal component analysis (PCA) method is introduced to reduce the dimension of feature vectors to reduce the efficiency of recognition and classification by overfitting. In order to verify the generality of this method, non-image defect data is introduced in addition to image defect data. Experimental results show that the present method can classify not only image defects but also non-image defects, and is superior to traditional machine learning methods in three evaluation indexes of recognition rate, equal to deep learning methods, but less time-consuming than deep learning in classification.
For recognition and classificationof metal defect, traditional machine learning requires manual feature extraction while deep learning requires a large number of samples. This paper proposes a classification method of metal defectbased on the shallow convolutional neural network (CNN) and decision tree (DT) for small and medium-sized defect data sets. The feature is extracted by the convolutional neural network, and the defect is classified with the decision tree. The principal component analysis (PCA) method is introduced to reduce the dimension of feature vectors to reduce the efficiency of recognition and classification by overfitting. In order to verify the generality of this method, non-image defect data is introduced in addition to image defect data. Experimental results show that the present method can classify not only image defects but also non-image defects, and is superior to traditional machine learning methods in three evaluation indexes of recognition rate, equal to deep learning methods, but less time-consuming than deep learning in classification.
2022, 41(9): 1428-1435.
doi: 10.13433/j.cnki.1003-8728.20200498
Abstract:
In order to unify the number of geometric error modeling methods for the machine measurement system, a more accurate geometric error model is established. Only the effect of the speed and spatial position on the machine error, a genetic algorithm to optimize the supporting vector return machine (GA-SVR) modeling methodis proposed. Taking the X-axis as an example, the error model is established by BP, GA-BP, SVR and GA-SVR algorithm, and modeling accuracy is compared. The experimental results show that the three geometric error based on the GA-SVR algorithm are higher, the maximum residuals of positioning errors, linearity errors, and angular error predictive values and measured truth are 0.179 6 μm, 0.067 57 μm and 0.019 2", respectively. More suitable for three geometric errors of machine tools and precise modeling and error compensation.
In order to unify the number of geometric error modeling methods for the machine measurement system, a more accurate geometric error model is established. Only the effect of the speed and spatial position on the machine error, a genetic algorithm to optimize the supporting vector return machine (GA-SVR) modeling methodis proposed. Taking the X-axis as an example, the error model is established by BP, GA-BP, SVR and GA-SVR algorithm, and modeling accuracy is compared. The experimental results show that the three geometric error based on the GA-SVR algorithm are higher, the maximum residuals of positioning errors, linearity errors, and angular error predictive values and measured truth are 0.179 6 μm, 0.067 57 μm and 0.019 2", respectively. More suitable for three geometric errors of machine tools and precise modeling and error compensation.
2022, 41(9): 1436-1441.
doi: 10.13433/j.cnki.1003-8728.20200500
Abstract:
In order to improve the cruising range and energy conversion rate of pure electric vehicles, a pure electric vehicle was taken as the research object, and a braking force distribution strategy based on the Economic Commission of Europe regulation curve, I curve and f curve was proposed. At the same time, taking into account the constraints of the maximum charging power of the motor and the battery, and after perfecting the regenerative torque of the motor and limiting the maximum value of regenerative braking, the fuzzy control method is adopted to determine the ratio of mechanical braking force and regenerative braking force according to different braking strengths, thereby formulating energy recovery control strategy. The regenerative braking control strategy model was established in MATLAB/Simulink and co-simulated with AVL-Cruise to analyze the optimization effect of this strategy. The simulation results show that the proposed control strategy can make full use of the motor braking torque on the basis of satisfying braking safety, so that the braking energy recovery rate is significantly improved compared with the system's own strategy, and to a certain extent, the battery life of the pure electric vehicles is prolonged.
In order to improve the cruising range and energy conversion rate of pure electric vehicles, a pure electric vehicle was taken as the research object, and a braking force distribution strategy based on the Economic Commission of Europe regulation curve, I curve and f curve was proposed. At the same time, taking into account the constraints of the maximum charging power of the motor and the battery, and after perfecting the regenerative torque of the motor and limiting the maximum value of regenerative braking, the fuzzy control method is adopted to determine the ratio of mechanical braking force and regenerative braking force according to different braking strengths, thereby formulating energy recovery control strategy. The regenerative braking control strategy model was established in MATLAB/Simulink and co-simulated with AVL-Cruise to analyze the optimization effect of this strategy. The simulation results show that the proposed control strategy can make full use of the motor braking torque on the basis of satisfying braking safety, so that the braking energy recovery rate is significantly improved compared with the system's own strategy, and to a certain extent, the battery life of the pure electric vehicles is prolonged.
2022, 41(9): 1442-1449.
doi: 10.13433/j.cnki.1003-8728.20200506
Abstract:
Firstly, the main performance indexes of the micro gas turbine range-extender are determined by matching calculations, and the design parameters of the micro radial turbine are obtained through model analysis in this paper. Secondly, according to the working principles of the radial turbine, its loss model is established, and its genetic algorithm is integrated into the design scheme. On this basis, its design processes and calculation programs are compiled.Finally, according to the design results, the structural design of the micro radial turbine is completed, and the CFD method is used for numerical simulation.The simulation results show that the peripheral efficiency, entropic efficiency and output power of the micro radial turbine thus designed meet the design requirements. Meanwhile, the internal flow fieldsimulation results show that the micro radial turbine has good aerodynamic performances, indicating that the design method adopted in the paper is reliable.
Firstly, the main performance indexes of the micro gas turbine range-extender are determined by matching calculations, and the design parameters of the micro radial turbine are obtained through model analysis in this paper. Secondly, according to the working principles of the radial turbine, its loss model is established, and its genetic algorithm is integrated into the design scheme. On this basis, its design processes and calculation programs are compiled.Finally, according to the design results, the structural design of the micro radial turbine is completed, and the CFD method is used for numerical simulation.The simulation results show that the peripheral efficiency, entropic efficiency and output power of the micro radial turbine thus designed meet the design requirements. Meanwhile, the internal flow fieldsimulation results show that the micro radial turbine has good aerodynamic performances, indicating that the design method adopted in the paper is reliable.
2022, 41(9): 1450-1457.
doi: 10.13433/j.cnki.1003-8728.20200492
Abstract:
Structural health monitoring method based on active Lamb wave will be disturbed by strong noise such as structural vibration and service environment noise, which affects the accuracy of damage location. Aiming at these problems, a probability-based diagnostic imaging method based on the improved damage factor under the environment of strong noise was proposed. The Locally Weighted Scatterplot Smoothing (LOWESS) method was used to smooth the envelope of the noisy signal after Hilbert Transform (HT), and the Time of Flight (ToF) for each channel was obtained. Then, the improved damage factor was obtained according to the ToF with or without damage, and combining with the damage probability-based diagnostic imaging method. The fatigue damage localization imaging was realized for the internal carbon fiber composite plate. The experiment result shows that this method can effectively locate the internal fatigue damage of the structure in the strong noise environment, improve the accuracy of the damage location, and the damage location error of the present method is 63.7% or more lower than that of the existing damage probability imaging method.
Structural health monitoring method based on active Lamb wave will be disturbed by strong noise such as structural vibration and service environment noise, which affects the accuracy of damage location. Aiming at these problems, a probability-based diagnostic imaging method based on the improved damage factor under the environment of strong noise was proposed. The Locally Weighted Scatterplot Smoothing (LOWESS) method was used to smooth the envelope of the noisy signal after Hilbert Transform (HT), and the Time of Flight (ToF) for each channel was obtained. Then, the improved damage factor was obtained according to the ToF with or without damage, and combining with the damage probability-based diagnostic imaging method. The fatigue damage localization imaging was realized for the internal carbon fiber composite plate. The experiment result shows that this method can effectively locate the internal fatigue damage of the structure in the strong noise environment, improve the accuracy of the damage location, and the damage location error of the present method is 63.7% or more lower than that of the existing damage probability imaging method.
2022, 41(9): 1458-1467.
doi: 10.13433/j.cnki.1003-8728.20220187
Abstract:
The civil aircraft nosewheel is clamped and lifted through the pick-up and holding system of the towbarless towing vehicles (TLTV), and the aircraft is towed to the destination such as the take-off position on the runway or the maintenance hangar only driven by the TLTV. Based on Newton's second law and the bending formula of beam, the vibration differential equation of the rigid-flexible coupled TLATS is derived by considering the flexibility of the TLTV frame. The ride comfort of key measurement points such as the TLTV seat, centre of gravity (CG) of the TLTV, and the airframe under both random and bump airport road excitations during low-speed and high-speed towing operation are comparatively analysed. The differences of the time-domain vibration characteristics between the quasi-static and dynamic TLATS models are discussed.The effects of aircraft sprung mass, TLTV frame flexibility, TLTV CG and driver seat positions on the ride comfort of the rigid-flexible coupled TLATS during high-speed towing operation are further investigated. The results show that properly changing some key parameters of the TLTV could improve the TLATS ride comfort.
The civil aircraft nosewheel is clamped and lifted through the pick-up and holding system of the towbarless towing vehicles (TLTV), and the aircraft is towed to the destination such as the take-off position on the runway or the maintenance hangar only driven by the TLTV. Based on Newton's second law and the bending formula of beam, the vibration differential equation of the rigid-flexible coupled TLATS is derived by considering the flexibility of the TLTV frame. The ride comfort of key measurement points such as the TLTV seat, centre of gravity (CG) of the TLTV, and the airframe under both random and bump airport road excitations during low-speed and high-speed towing operation are comparatively analysed. The differences of the time-domain vibration characteristics between the quasi-static and dynamic TLATS models are discussed.The effects of aircraft sprung mass, TLTV frame flexibility, TLTV CG and driver seat positions on the ride comfort of the rigid-flexible coupled TLATS during high-speed towing operation are further investigated. The results show that properly changing some key parameters of the TLTV could improve the TLATS ride comfort.
2022, 41(9): 1468-1474.
doi: 10.13433/j.cnki.1003-8728.20200473
Abstract:
Based on the validated ALE modeling method, a typical aircraft wing damage model was established by LS-DYNA. The effects of explosion equivalent, distance and direction of explosion point on typical aircraft wing under blast wave damage were analyzed. The results show that the skin first appears local concave deformation under the action of explosion shock wave, and then expands rapidly; but the inner stringer/wing rib knot inhibits the deformation; with the further deformation of the skin, the initial tearing crack appears at the junction of the stringer and wing rib. The damage range and mode of the wing are greatly affected by explosion equivalent, explosion distance and explosion direction. And with the increase of TNT equivalent or the decrease of explosion distance, the earlier and the greater the deformation will be. When the explosion point is located in the front of the wing, the wing has a large deformation on the leading structure which affects the aerodynamic characteristics. When the explosion point is located at the back of the wing, it may lead to the failure of the control surface.
Based on the validated ALE modeling method, a typical aircraft wing damage model was established by LS-DYNA. The effects of explosion equivalent, distance and direction of explosion point on typical aircraft wing under blast wave damage were analyzed. The results show that the skin first appears local concave deformation under the action of explosion shock wave, and then expands rapidly; but the inner stringer/wing rib knot inhibits the deformation; with the further deformation of the skin, the initial tearing crack appears at the junction of the stringer and wing rib. The damage range and mode of the wing are greatly affected by explosion equivalent, explosion distance and explosion direction. And with the increase of TNT equivalent or the decrease of explosion distance, the earlier and the greater the deformation will be. When the explosion point is located in the front of the wing, the wing has a large deformation on the leading structure which affects the aerodynamic characteristics. When the explosion point is located at the back of the wing, it may lead to the failure of the control surface.
