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RSS2024 Vol. 43, No. 4
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2024, 43(4): 553-558.
doi: 10.13433/j.cnki.1003-8728.20220263
PDF 1921KB
Abstract:
The combination of optimization algorithm with the finite element simulation analysis can reverse the parameters of rubber materials. This method is based on the experimental data of a laminated rubber spring, and the Mooney-Rivlin hyperelastic constitutive model is selected. In the process of parameter inversion, in order to solve the problem of prematurity, poor stability and slow convergence of the traditional genetic algorithm, the coding method is changed into real number coding, and the elite retention strategy, adaptive crossover, mutation probability are also introduced into the algorithm. The stiffness characteristic curve obtained with the improved genetic algorithm is compared with the experimental results, which are in good agreement with the stiffness characteristic curve, indicating that the inversed parameters can accurately describe the mechanical properties of rubber materials.
The combination of optimization algorithm with the finite element simulation analysis can reverse the parameters of rubber materials. This method is based on the experimental data of a laminated rubber spring, and the Mooney-Rivlin hyperelastic constitutive model is selected. In the process of parameter inversion, in order to solve the problem of prematurity, poor stability and slow convergence of the traditional genetic algorithm, the coding method is changed into real number coding, and the elite retention strategy, adaptive crossover, mutation probability are also introduced into the algorithm. The stiffness characteristic curve obtained with the improved genetic algorithm is compared with the experimental results, which are in good agreement with the stiffness characteristic curve, indicating that the inversed parameters can accurately describe the mechanical properties of rubber materials.
2024, 43(4): 559-565.
doi: 10.13433/j.cnki.1003-8728.20220244
Abstract:
Aiming at the nonlinear factors such as flexible deformation, friction and motion error in the dynamic model of harmonic transmission system, in order to improve the transmission accuracy of the system, the nonlinear stiffness and static error factors of the system are modeled, and a Back-stepping sliding mode control method is proposed in this paper. Using Lyapunov stability theory, it is proved that the error of the closed-loop system is uniformly bounded. The simulation results show that compared with PID control, the peak-peak value of the transmission error curve of the system is reduced by 66.63% with the Back-stepping sliding mode control; The peak-peak value of the angular rate error curve at the load end is reduced by 77.35%. Back stepping sliding mode control can effectively compensate the transmission error of the system, suppress the speed fluctuation at the load end, and improve the transmission accuracy of the system.
Aiming at the nonlinear factors such as flexible deformation, friction and motion error in the dynamic model of harmonic transmission system, in order to improve the transmission accuracy of the system, the nonlinear stiffness and static error factors of the system are modeled, and a Back-stepping sliding mode control method is proposed in this paper. Using Lyapunov stability theory, it is proved that the error of the closed-loop system is uniformly bounded. The simulation results show that compared with PID control, the peak-peak value of the transmission error curve of the system is reduced by 66.63% with the Back-stepping sliding mode control; The peak-peak value of the angular rate error curve at the load end is reduced by 77.35%. Back stepping sliding mode control can effectively compensate the transmission error of the system, suppress the speed fluctuation at the load end, and improve the transmission accuracy of the system.
2024, 43(4): 566-572.
doi: 10.13433/j.cnki.1003-8728.20220287
Abstract:
Imitation of the gait of real animals is a focus on the gait planning research for bionic robot. In this paper, aiming at the gait planning of a new type of bionic crocodile robot, the motion capture technology is used to obtain the gait of the real crocodile. On this basis, the angle of the leg joint of the crocodile robot was solved by the Gauss-Newton method. Bionic gait obtained by fitting is similar to the real gait trajectory, and the kinematic stability of the crocodile robot in this gait was analyzed. The kinematic simulation results of the virtual prototype show that the crocodile robot can crawl forward at a speed of 0.3 m/s with a gait similar to that of the real crocodile and has high stability.
Imitation of the gait of real animals is a focus on the gait planning research for bionic robot. In this paper, aiming at the gait planning of a new type of bionic crocodile robot, the motion capture technology is used to obtain the gait of the real crocodile. On this basis, the angle of the leg joint of the crocodile robot was solved by the Gauss-Newton method. Bionic gait obtained by fitting is similar to the real gait trajectory, and the kinematic stability of the crocodile robot in this gait was analyzed. The kinematic simulation results of the virtual prototype show that the crocodile robot can crawl forward at a speed of 0.3 m/s with a gait similar to that of the real crocodile and has high stability.
2024, 43(4): 573-581.
doi: 10.13433/j.cnki.1003-8728.20220288
Abstract:
Because of the poor robustness and accuracy of the conventional Kalman filter for vehicle state estimation in the non-Gaussian environment, an improved adaptive iterative extended Kalman filtering (AIEKF) algorithm (MC-AIEKF) under the maximum correntropy criterion (MCC) is proposed. A three-degree-of-freedom lateral-longitudinal coupled vehicle model is established, and a state observer containing the yaw rate, mass-central sideslip angle and longitudinal speed of the vehicle is designed by utilizing the easily available information on onboard sensor. The proposed algorithm is verified with the Simulink/CarSim simulation platform under the conditions of double lane change and sine sweep input. The results show that the MC-AIEKF algorithm has higher estimation accuracy and better robustness than the extended Kalman filtering (EKF) and the AIEKF in the non-Gaussian environment, being more applicable for vehicle state estimation in real situations.
Because of the poor robustness and accuracy of the conventional Kalman filter for vehicle state estimation in the non-Gaussian environment, an improved adaptive iterative extended Kalman filtering (AIEKF) algorithm (MC-AIEKF) under the maximum correntropy criterion (MCC) is proposed. A three-degree-of-freedom lateral-longitudinal coupled vehicle model is established, and a state observer containing the yaw rate, mass-central sideslip angle and longitudinal speed of the vehicle is designed by utilizing the easily available information on onboard sensor. The proposed algorithm is verified with the Simulink/CarSim simulation platform under the conditions of double lane change and sine sweep input. The results show that the MC-AIEKF algorithm has higher estimation accuracy and better robustness than the extended Kalman filtering (EKF) and the AIEKF in the non-Gaussian environment, being more applicable for vehicle state estimation in real situations.
2024, 43(4): 582-590.
doi: 10.13433/j.cnki.1003-8728.20240047
Abstract:
To address the complex technical challenges in modeling the hysteresis nonlinearity of piezoelectric actuators, this article proposed a nonlinear modeling approach based on the modified Rayleigh model. Firstly, starting from the microscopic structure of piezoelectric ceramic materials, a linear constitutive equation for piezoelectric actuators is established. Then, based on the analysis of causes and microscopic mechanisms of the hysteresis effect, a nonlinear modeling method using the Rayleigh model is proposed. On this basis, a first-order linear equation is used to describe the frequency-dependent characteristics of piezoelectric actuators and its validity is verified through experiments. Subsequently, an asymmetric Rayleigh model with dual Rayleigh coefficients is constructed. Finally, the applicability of the Rayleigh model in the sub-loop response of piezoelectric actuators is experimentally verified.
To address the complex technical challenges in modeling the hysteresis nonlinearity of piezoelectric actuators, this article proposed a nonlinear modeling approach based on the modified Rayleigh model. Firstly, starting from the microscopic structure of piezoelectric ceramic materials, a linear constitutive equation for piezoelectric actuators is established. Then, based on the analysis of causes and microscopic mechanisms of the hysteresis effect, a nonlinear modeling method using the Rayleigh model is proposed. On this basis, a first-order linear equation is used to describe the frequency-dependent characteristics of piezoelectric actuators and its validity is verified through experiments. Subsequently, an asymmetric Rayleigh model with dual Rayleigh coefficients is constructed. Finally, the applicability of the Rayleigh model in the sub-loop response of piezoelectric actuators is experimentally verified.
2024, 43(4): 591-599.
doi: 10.13433/j.cnki.1003-8728.20220251
Abstract:
In the design of power ultrasonic plastic riveted horn, the resonant frequency and amplitude of longitudinal wave are the key parameters to the design. In an engineering practice, the stepped riveted horn is taken as the design object. In the finite element modal analysis, the natural frequency of longitudinal wave is 19 982 Hz. The resonance frequency of its harmonic sweep response is 20 082 Hz. In impedance analysis, the resonance frequency of the stepped riveted horn vibration is 19 813 Hz. In general, the error change rate between three frequencies is small. Under the condition that the material damping rate is 0.004, the maximum amplitude displacement at the end of horn with harmonic response is 59.16 μm. Using laser vibrometer, the amplitude of the end of horn is about 49.8 μm. The error between them is also very small. Practical processing verification, the riveting effect is better. The results show that the natural mode, harmonic response, impedance analysis and amplitude test analysis can provide efficient analysis and test methods for the engineering design of ultrasonic horn.
In the design of power ultrasonic plastic riveted horn, the resonant frequency and amplitude of longitudinal wave are the key parameters to the design. In an engineering practice, the stepped riveted horn is taken as the design object. In the finite element modal analysis, the natural frequency of longitudinal wave is 19 982 Hz. The resonance frequency of its harmonic sweep response is 20 082 Hz. In impedance analysis, the resonance frequency of the stepped riveted horn vibration is 19 813 Hz. In general, the error change rate between three frequencies is small. Under the condition that the material damping rate is 0.004, the maximum amplitude displacement at the end of horn with harmonic response is 59.16 μm. Using laser vibrometer, the amplitude of the end of horn is about 49.8 μm. The error between them is also very small. Practical processing verification, the riveting effect is better. The results show that the natural mode, harmonic response, impedance analysis and amplitude test analysis can provide efficient analysis and test methods for the engineering design of ultrasonic horn.
2024, 43(4): 600-610.
doi: 10.13433/j.cnki.1003-8728.20220246
Abstract:
The traditional two-dimensional convolutional neural network (2D CNN) not only has high computational complexity and is easier to over fitting, but also is difficult to deal with low signal-to-noise ratio (SNR) signal effectively. In order to overcome the shortcomings of 2D CNN, a new fault diagnosis method based on cyclic correntropy (CCe) and one-dimensional shallow convolutional neural network (1D SCNN) is proposed. This new method (CCe-1D SCNN) makes fully use of the advantages of 1D SCNN and CCe, in which the 1D SCNN has simple structure and low computational complexity. Firstly, the cyclic correntropy function, the cyclic correntropy spectral density (CCSD) function and generalized degree of cyclostationary (DCS) of bearing fault vibration signal are calculated. Secondly, the one-dimensional normalized generalized degree of cyclostationary is used as the input layer of one-dimensional shallow convolutional neural network. The fault feature extraction and pattern classification are automatically realized by one-dimensional shallow convolutional neural network. Finally, the CCe-1D SCNN method is applied to fault feature extraction and pattern classification of motor bearing fault. The experimental results show that the CCe-1D SCNN technique can still maintain a high accuracy of pattern recognition in the case of very low signal-to-noise ratio, which is an effective method for automatic fault feature extraction and pattern recognition.
The traditional two-dimensional convolutional neural network (2D CNN) not only has high computational complexity and is easier to over fitting, but also is difficult to deal with low signal-to-noise ratio (SNR) signal effectively. In order to overcome the shortcomings of 2D CNN, a new fault diagnosis method based on cyclic correntropy (CCe) and one-dimensional shallow convolutional neural network (1D SCNN) is proposed. This new method (CCe-1D SCNN) makes fully use of the advantages of 1D SCNN and CCe, in which the 1D SCNN has simple structure and low computational complexity. Firstly, the cyclic correntropy function, the cyclic correntropy spectral density (CCSD) function and generalized degree of cyclostationary (DCS) of bearing fault vibration signal are calculated. Secondly, the one-dimensional normalized generalized degree of cyclostationary is used as the input layer of one-dimensional shallow convolutional neural network. The fault feature extraction and pattern classification are automatically realized by one-dimensional shallow convolutional neural network. Finally, the CCe-1D SCNN method is applied to fault feature extraction and pattern classification of motor bearing fault. The experimental results show that the CCe-1D SCNN technique can still maintain a high accuracy of pattern recognition in the case of very low signal-to-noise ratio, which is an effective method for automatic fault feature extraction and pattern recognition.
2024, 43(4): 611-618.
doi: 10.13433/j.cnki.1003-8728.20240055
Abstract:
The parameters of the constitutive model for fan disk material are identified. In order to fit the finite element model with accurate stress field in the machining, the empirical formula of residual stress of TC11 titanium alloy is modeled, and the simulation method of residual stress is studied. The simulation modeling and verification are carried out on the small end of the fan disk semi-finishing turning. The processing parameters are optimized based on the simulation results of residual stress, and the effectiveness of the method is verified by an example.
The parameters of the constitutive model for fan disk material are identified. In order to fit the finite element model with accurate stress field in the machining, the empirical formula of residual stress of TC11 titanium alloy is modeled, and the simulation method of residual stress is studied. The simulation modeling and verification are carried out on the small end of the fan disk semi-finishing turning. The processing parameters are optimized based on the simulation results of residual stress, and the effectiveness of the method is verified by an example.
2024, 43(4): 619-627.
doi: 10.13433/j.cnki.1003-8728.20220253
Abstract:
As a common material in the aviation industry, the residual stresses of titanium alloy after machining can seriously affect the service life of the components. In this study, a finite element model based on the Coupled Eulerian-Lagrangian (CEL) method in the machining of titanium alloy was established, and the orthogonal experimental platform was used to obtain the chip morphology and residual stresses to verify the validity of the model. The present model was compared with the traditional Lagrangian and Arbitrary Lagrange-Eulerian (ALE) methods, the results show that although the CEL method takes a long time, the prediction results are more accurate without mesh distortion and have the best comprehensive performance. Finally, the present method was used to investigate the chip morphology and residual stresses on the machined surface under the different feeds and edge radius. The results show that the degree of chip serration and equivalent chip thickness increase with the increasing of feed and edge radius, and the residual stresses of surface become more compressive.
As a common material in the aviation industry, the residual stresses of titanium alloy after machining can seriously affect the service life of the components. In this study, a finite element model based on the Coupled Eulerian-Lagrangian (CEL) method in the machining of titanium alloy was established, and the orthogonal experimental platform was used to obtain the chip morphology and residual stresses to verify the validity of the model. The present model was compared with the traditional Lagrangian and Arbitrary Lagrange-Eulerian (ALE) methods, the results show that although the CEL method takes a long time, the prediction results are more accurate without mesh distortion and have the best comprehensive performance. Finally, the present method was used to investigate the chip morphology and residual stresses on the machined surface under the different feeds and edge radius. The results show that the degree of chip serration and equivalent chip thickness increase with the increasing of feed and edge radius, and the residual stresses of surface become more compressive.
Evolution and Quantitative Analysis of Force Chain in Process of Horizontal Vibration Mass Finishing
2024, 43(4): 628-636.
doi: 10.13433/j.cnki.1003-8728.20220258
Abstract:
In the process of mass finishing, the internal force chain network in media between masses affects the macroscopic behavior of granular matter, then affects the processing effect. In this paper, the numerical simulation model of horizontal vibration mass finishing is established to analyze the relationship between the dynamic evolution mechanism of mesoscopic force chain network and macroscopic motion behavior of granular media, and the quantitative characterization of force chain network is studied. The results show that the complex temporal and spatial distribution of force chain network determines the macroscopic motion behavior of granular matter. Increasing the excitation parameters, the fluidization appearance occurred in the granular media, the number of force chains decreases, the length and alignment coefficient of the strong chains decrease, but the strength increases, and the directivity tends to the gravity direction. The research provides an analytical method for forming the multi-scale research strategy of the mass finishing.
In the process of mass finishing, the internal force chain network in media between masses affects the macroscopic behavior of granular matter, then affects the processing effect. In this paper, the numerical simulation model of horizontal vibration mass finishing is established to analyze the relationship between the dynamic evolution mechanism of mesoscopic force chain network and macroscopic motion behavior of granular media, and the quantitative characterization of force chain network is studied. The results show that the complex temporal and spatial distribution of force chain network determines the macroscopic motion behavior of granular matter. Increasing the excitation parameters, the fluidization appearance occurred in the granular media, the number of force chains decreases, the length and alignment coefficient of the strong chains decrease, but the strength increases, and the directivity tends to the gravity direction. The research provides an analytical method for forming the multi-scale research strategy of the mass finishing.
2024, 43(4): 637-642.
doi: 10.13433/j.cnki.1003-8728.20220243
Abstract:
In order to realize high-precision machining of SiC ceramics, laser irradiation is introduced into the grinding process. In this paper, SiC ceramics as research material, by using laser modified grinding (LMG) process, and then the grinding experiments of SiC ceramics modified by laser irradiation were carried out. Comparing with the ordinary grinding (OG), the grinding force, surface roughness, surface morphology and subsurface damage of SiC ceramic samples were studied. The experimental results show that LMG can effectively reduce normal grinding force, tangential grinding force and surface roughness, and the maximum decreases are 33.91%, 37.31% and 33.14%, respectively. LMG promotes the plastic removal of SiC ceramics in the grinding process, and the grinding surface is regular and smooth. There are fewer micro-cracks on the workpiece subsurface, and the subsurface damage depth is small. The plastic removal with a large grinding depth is realized, and the grinding quality of SiC ceramics is improved.
In order to realize high-precision machining of SiC ceramics, laser irradiation is introduced into the grinding process. In this paper, SiC ceramics as research material, by using laser modified grinding (LMG) process, and then the grinding experiments of SiC ceramics modified by laser irradiation were carried out. Comparing with the ordinary grinding (OG), the grinding force, surface roughness, surface morphology and subsurface damage of SiC ceramic samples were studied. The experimental results show that LMG can effectively reduce normal grinding force, tangential grinding force and surface roughness, and the maximum decreases are 33.91%, 37.31% and 33.14%, respectively. LMG promotes the plastic removal of SiC ceramics in the grinding process, and the grinding surface is regular and smooth. There are fewer micro-cracks on the workpiece subsurface, and the subsurface damage depth is small. The plastic removal with a large grinding depth is realized, and the grinding quality of SiC ceramics is improved.
2024, 43(4): 643-649.
doi: 10.13433/j.cnki.1003-8728.20240046
Abstract:
In this paper, Ti-6Al-4V ELI(TC4) titanium alloy is machined by end face milling, and the surface quality of the workpiece is predicted and the best cutting parameter is determined by combining the processing parameters. In order to realize the accurate prediction of workpiece surface quality, the corresponding experiments were carried out in three-axis CNC machining center. Based on Box Behnken method (BBD), the experiment was designed with four factors and three levels to reduce the number of experiments. In the experiment, the cutting depth, cutting width, cutting speed and feed per tooth are selected as the input parameters, and the surface roughness measured in each experiment is taken as the output parameters. Finally, the Response Surface Methodology (RSM) is used to establish the quadratic relationship between the input and the output parameters, and the analysis of variance (ANOVA) is conducted to evaluate the established model. At the same time, RSM is used to optimize the analysis and determine the milling parameters to achieve the minimum surface roughness. The analysis shows that the quadratic regression model for milling parameters and surface roughness is established via RSM, and its correction coefficient reaches 96.16%. The model can well reflect the mapping relationship between the input parameters and the surface roughness, and this method can provide the reliable surface roughness prediction for any cutting conditions within the input parameters. Through optimization analysis and experimental verification, the obtained milling parameters can obtain the smaller surface roughness, which can be applied to optimize the process in practice.
In this paper, Ti-6Al-4V ELI(TC4) titanium alloy is machined by end face milling, and the surface quality of the workpiece is predicted and the best cutting parameter is determined by combining the processing parameters. In order to realize the accurate prediction of workpiece surface quality, the corresponding experiments were carried out in three-axis CNC machining center. Based on Box Behnken method (BBD), the experiment was designed with four factors and three levels to reduce the number of experiments. In the experiment, the cutting depth, cutting width, cutting speed and feed per tooth are selected as the input parameters, and the surface roughness measured in each experiment is taken as the output parameters. Finally, the Response Surface Methodology (RSM) is used to establish the quadratic relationship between the input and the output parameters, and the analysis of variance (ANOVA) is conducted to evaluate the established model. At the same time, RSM is used to optimize the analysis and determine the milling parameters to achieve the minimum surface roughness. The analysis shows that the quadratic regression model for milling parameters and surface roughness is established via RSM, and its correction coefficient reaches 96.16%. The model can well reflect the mapping relationship between the input parameters and the surface roughness, and this method can provide the reliable surface roughness prediction for any cutting conditions within the input parameters. Through optimization analysis and experimental verification, the obtained milling parameters can obtain the smaller surface roughness, which can be applied to optimize the process in practice.
2024, 43(4): 650-659.
doi: 10.13433/j.cnki.1003-8728.20220252
Abstract:
An aerostatic spindle is studied in which the its orifices are distributed unevenly and have different diameters and to improve its static and dynamic characteristics. The effects of different orifice diameters and uneven distributions on bearing load capacity are analysed with Finite Difference Method combined with Linear Perturbation Method. The influences of circumferential or axial manufacturing errors (sine waviness, square waviness, triangular waviness) in sleeve on static and dynamic performances are analysed. The results indicate that the bearing capacity of aerostatic spindle increased most significantly if orifice diameter coefficient is within 0.9~0.95. Circumferential and axial manufacturing errors improve bearing capacity. Square waviness and triangular waviness have more significant influence on bearing capacity. Axial square waviness and triangular waviness are hopeful for dissipating the whirling energy and improving the stability of the spindle. The larger the amplitude of manufacturing errors is, the worse the stability of the spindle is.
An aerostatic spindle is studied in which the its orifices are distributed unevenly and have different diameters and to improve its static and dynamic characteristics. The effects of different orifice diameters and uneven distributions on bearing load capacity are analysed with Finite Difference Method combined with Linear Perturbation Method. The influences of circumferential or axial manufacturing errors (sine waviness, square waviness, triangular waviness) in sleeve on static and dynamic performances are analysed. The results indicate that the bearing capacity of aerostatic spindle increased most significantly if orifice diameter coefficient is within 0.9~0.95. Circumferential and axial manufacturing errors improve bearing capacity. Square waviness and triangular waviness have more significant influence on bearing capacity. Axial square waviness and triangular waviness are hopeful for dissipating the whirling energy and improving the stability of the spindle. The larger the amplitude of manufacturing errors is, the worse the stability of the spindle is.
2024, 43(4): 660-666.
doi: 10.13433/j.cnki.1003-8728.20220260
Abstract:
In order to explore the key effects of the surface quality in milling of 7050 aluminum alloy and the optimal processing parameters, the orthogonal experiment of 7050 aluminum alloy under the condition of flushing was carried out, and the regression model between the surface roughness and the cutting depth, feed rate and spindle speed was established. The differences of machined trace caused by the different relative states between the tool and the workpiece during the machining were analysed. The results showed that the cutting depth had the greatest influence on the surface roughness, followed by the spindle speed and the feed rate. The manifestation of the machined trace was directly related to the tool-workpiece contact state. The unidirectional arc-shaped traces could be found when the tool cut into the workpiece, mainly affecting by the cutting depth. The staggered arc-shaped traces were formed while milling in the middle of the workpiece. The shallower traces occurred when the tool cut out of the workpiece because of the feed rate.
In order to explore the key effects of the surface quality in milling of 7050 aluminum alloy and the optimal processing parameters, the orthogonal experiment of 7050 aluminum alloy under the condition of flushing was carried out, and the regression model between the surface roughness and the cutting depth, feed rate and spindle speed was established. The differences of machined trace caused by the different relative states between the tool and the workpiece during the machining were analysed. The results showed that the cutting depth had the greatest influence on the surface roughness, followed by the spindle speed and the feed rate. The manifestation of the machined trace was directly related to the tool-workpiece contact state. The unidirectional arc-shaped traces could be found when the tool cut into the workpiece, mainly affecting by the cutting depth. The staggered arc-shaped traces were formed while milling in the middle of the workpiece. The shallower traces occurred when the tool cut out of the workpiece because of the feed rate.
2024, 43(4): 667-673.
doi: 10.13433/j.cnki.1003-8728.20220269
Abstract:
To realize the tool wear condition monitoring in the production of a vehicle engine's cylinder head and to enhance the computational efficiency and recognition accuracy of tool wear monitoring, a tool condition monitoring method based on the gated recurrent unit neural network and the multi-feature fusion method is proposed for identifying the width of milling tool flank wear. The effectiveness of the proposed method is verified with the milling force signal data, and the effects of different hyper-parameter settings on the model recognition accuracy is analyzed. The optimal hyper-parameters are given; the accurate recognition of milling tool wear is realized.
To realize the tool wear condition monitoring in the production of a vehicle engine's cylinder head and to enhance the computational efficiency and recognition accuracy of tool wear monitoring, a tool condition monitoring method based on the gated recurrent unit neural network and the multi-feature fusion method is proposed for identifying the width of milling tool flank wear. The effectiveness of the proposed method is verified with the milling force signal data, and the effects of different hyper-parameter settings on the model recognition accuracy is analyzed. The optimal hyper-parameters are given; the accurate recognition of milling tool wear is realized.
2024, 43(4): 674-680.
doi: 10.13433/j.cnki.1003-8728.20220257
Abstract:
A new type of roll forming process is proposed, and a new design idea is proposed for the contour design of the main and auxiliary forming rollers, and the micro groove of TA1 titanium plate with a thickness of 0.1 mm (a depth of 2.5 mm, an aspect ratio of 86.2%). The roll forming test was carried out, and the maximum thinning rate and the maximum depth deviation were used as the evaluation indicators to verify the rationality and scientificity of the process. The results show that under the satisfying the deflection (< 0.02 mm) of the auxiliary forming roller, the number of features of the auxiliary forming roller should be reduced as much as possible, so that the sheet is bent instead of drawing during the rolling of sheet metal, and its maximum thinning rate is less than 0.4%, and the depth deviation is less than 0.5%. With the stamping die, the micro grooves with large aspect ratio can be formed without the influence of the draft angle. This new forming process can promote the production of sheet metal micro-grooves.
A new type of roll forming process is proposed, and a new design idea is proposed for the contour design of the main and auxiliary forming rollers, and the micro groove of TA1 titanium plate with a thickness of 0.1 mm (a depth of 2.5 mm, an aspect ratio of 86.2%). The roll forming test was carried out, and the maximum thinning rate and the maximum depth deviation were used as the evaluation indicators to verify the rationality and scientificity of the process. The results show that under the satisfying the deflection (< 0.02 mm) of the auxiliary forming roller, the number of features of the auxiliary forming roller should be reduced as much as possible, so that the sheet is bent instead of drawing during the rolling of sheet metal, and its maximum thinning rate is less than 0.4%, and the depth deviation is less than 0.5%. With the stamping die, the micro grooves with large aspect ratio can be formed without the influence of the draft angle. This new forming process can promote the production of sheet metal micro-grooves.
Fault Diagnosis Method of Rolling Bearing Combining Jump Connected Variational Auto-encoder with CNN
2024, 43(4): 681-689.
doi: 10.13433/j.cnki.1003-8728.20220273
Abstract:
For the problem that the failure rate of rolling bearings is small and it is not easy to collect fault data, a novel rolling bearing fault diagnosis method with small samples is proposed, which combines respective advantages of jumping connection variational auto-encoder and deep convolution neural network with wide kernel. The proposed method firstly introduces a jump connection structure between encoding and decoding of the variational auto-encoder, and Tanh is used as the activation function of the network, thus improving the feature diversity of the generated samples. Secondly, the diagnosis model of wide kernel deep convolution network is constructed, aiming to enhance the capability of fault feature extraction from vibration signals. Finally, the data set expanded by the generated samples is used as the model input to improve the amount of feature information contained in the training set, thereby realizing bearing fault diagnosis under small samples. Experimental analysis shows that the proposed method can generate effective fake samples and gains high diagnostic accuracy in the case of small samples.
For the problem that the failure rate of rolling bearings is small and it is not easy to collect fault data, a novel rolling bearing fault diagnosis method with small samples is proposed, which combines respective advantages of jumping connection variational auto-encoder and deep convolution neural network with wide kernel. The proposed method firstly introduces a jump connection structure between encoding and decoding of the variational auto-encoder, and Tanh is used as the activation function of the network, thus improving the feature diversity of the generated samples. Secondly, the diagnosis model of wide kernel deep convolution network is constructed, aiming to enhance the capability of fault feature extraction from vibration signals. Finally, the data set expanded by the generated samples is used as the model input to improve the amount of feature information contained in the training set, thereby realizing bearing fault diagnosis under small samples. Experimental analysis shows that the proposed method can generate effective fake samples and gains high diagnostic accuracy in the case of small samples.
2024, 43(4): 690-697.
doi: 10.13433/j.cnki.1003-8728.20220264
Abstract:
Aiming at the problems that conditional generative adversarial nets (CGAN) can only judge truth or false and not judge multiple classification, and semi-supervised generative adversarial nets (SGAN) needs to discriminate multiple classification and judge truth and false simultaneously, an improved generative adversarial nets called conditional semi-supervised generative adversarial nets (CSGAN) is proposed in this paper, and its specific design is also given. The generator of the CSGAN is based on CGAN and composed of multi-layer perceptron (MLP), and the discriminator of the CSGAN is based on SGAN and consists of convolutional neural networks (CNN). Based on CSGAN, a 2-D GAN method for bearing fault diagnosis is proposed. Firstly, the original fault signals are normalized to the interval [-1, 1], and then a sliding window is used to intercept 1024 length data from the normalized data, which is converted into a 2-D matrix with a size of 32×32 as the input of CSGAN. The validation of experiments on several public data sets shows that this method can effectively improve the diagnostic accuracy of the discriminator under different sample proportions and has good applicability.
Aiming at the problems that conditional generative adversarial nets (CGAN) can only judge truth or false and not judge multiple classification, and semi-supervised generative adversarial nets (SGAN) needs to discriminate multiple classification and judge truth and false simultaneously, an improved generative adversarial nets called conditional semi-supervised generative adversarial nets (CSGAN) is proposed in this paper, and its specific design is also given. The generator of the CSGAN is based on CGAN and composed of multi-layer perceptron (MLP), and the discriminator of the CSGAN is based on SGAN and consists of convolutional neural networks (CNN). Based on CSGAN, a 2-D GAN method for bearing fault diagnosis is proposed. Firstly, the original fault signals are normalized to the interval [-1, 1], and then a sliding window is used to intercept 1024 length data from the normalized data, which is converted into a 2-D matrix with a size of 32×32 as the input of CSGAN. The validation of experiments on several public data sets shows that this method can effectively improve the diagnostic accuracy of the discriminator under different sample proportions and has good applicability.
2024, 43(4): 698-703.
doi: 10.13433/j.cnki.1003-8728.20220247
Abstract:
Power shunt transmission system has been widely used in high-power transmission due to its advantages of strong bearing capacity, large transmission ratio, and compact structure. When each branch gear is fitted, the adjacency condition and transmission ratio condition are considered, and the collision between the gears is avoided, and the interference caused by each pair of gear meshing has become one of the key problems to be considered in the design of the system. Based on the six-branches coaxial transmission power configuration in this paper, a judgment condition is proposed which is easier to determine whether four gear mesh produce interference; and combined with modified gear, they established the teeth matching method of six-branch herringbone gear, which not only can quickly calculate the displacement coefficient of gear mesh not to produce interference, but also obtain the multi-group schemes satisfying transmission ratio and interference error requirements. The calculation results show that the gear design parameters obtained by this method meet all the requirements, which provides a practical method and theoretical basis for the design of a six-branch herringbone gear transmission system in a ship power system.
Power shunt transmission system has been widely used in high-power transmission due to its advantages of strong bearing capacity, large transmission ratio, and compact structure. When each branch gear is fitted, the adjacency condition and transmission ratio condition are considered, and the collision between the gears is avoided, and the interference caused by each pair of gear meshing has become one of the key problems to be considered in the design of the system. Based on the six-branches coaxial transmission power configuration in this paper, a judgment condition is proposed which is easier to determine whether four gear mesh produce interference; and combined with modified gear, they established the teeth matching method of six-branch herringbone gear, which not only can quickly calculate the displacement coefficient of gear mesh not to produce interference, but also obtain the multi-group schemes satisfying transmission ratio and interference error requirements. The calculation results show that the gear design parameters obtained by this method meet all the requirements, which provides a practical method and theoretical basis for the design of a six-branch herringbone gear transmission system in a ship power system.
2024, 43(4): 704-710.
doi: 10.13433/j.cnki.1003-8728.20220256
Abstract:
Aircraft seat belt is a key component to ensure the safety of passengers. In order to study the tensile mechanical properties of aircraft seat belt webbing, the tensile performance experiments of the AM SAFE seat belt webbing were carried out with the electronic universal testing machine under the loading rates of 6.35 mm/min, 30 mm/min, 152.4 mm/min, and the gauge segment sizes of 160 mm and 254 mm, and considering the influence of secondary loading. Moreover, three types of seat belt modeling methods, known as the segment belt, the finite element belt, the hybrid belt, were respectively used to simulate and compare the stretching process of seat belt webbing based on the experimental results. The results show that the hysteresis effect of the seat belt webbing is obvious, and the energy dissipation effect is significant; its tensile mechanical properties are little affected by the loading rate, but are greatly affected by the size of the gauge length, and are closely related to the loading times; all three modeling methods can better characterize the tensile mechanical properties of the seat belt webbing.
Aircraft seat belt is a key component to ensure the safety of passengers. In order to study the tensile mechanical properties of aircraft seat belt webbing, the tensile performance experiments of the AM SAFE seat belt webbing were carried out with the electronic universal testing machine under the loading rates of 6.35 mm/min, 30 mm/min, 152.4 mm/min, and the gauge segment sizes of 160 mm and 254 mm, and considering the influence of secondary loading. Moreover, three types of seat belt modeling methods, known as the segment belt, the finite element belt, the hybrid belt, were respectively used to simulate and compare the stretching process of seat belt webbing based on the experimental results. The results show that the hysteresis effect of the seat belt webbing is obvious, and the energy dissipation effect is significant; its tensile mechanical properties are little affected by the loading rate, but are greatly affected by the size of the gauge length, and are closely related to the loading times; all three modeling methods can better characterize the tensile mechanical properties of the seat belt webbing.
2024, 43(4): 711-720.
doi: 10.13433/j.cnki.1003-8728.20220282
Abstract:
In order to study the influence of the tension state of metal reflective net and cable net on the shape accuracy of deployable antenna, the form-state design of deployable antenna with cable membrane reflector is studied considering the deformation of support truss. Metal reflective net can be regarded as a kind of membrane structure, and both metal reflective net and cable net need to apply pretension to achieve a certain stiffness. Therefore, firstly the form-state design is carried out based on the force density equation of cable membrane structure to make it meet the requirement of the shape and accuracy under its own pretension and external load. The tension of cable membrane structure will lead to truss deformation, and after rebalancing, resulting in the reduction of shape accuracy of cable membrane reflector and unreasonable tension distribution. Therefore, it is necessary to establish the nonlinear finite element model for the whole antenna. By iteratively modifying the antenna model, the tension design variables and configuration of deployable antenna are obtained. The present method is programmed for a corresponding example at last, and the results indicate that the method is feasible.
In order to study the influence of the tension state of metal reflective net and cable net on the shape accuracy of deployable antenna, the form-state design of deployable antenna with cable membrane reflector is studied considering the deformation of support truss. Metal reflective net can be regarded as a kind of membrane structure, and both metal reflective net and cable net need to apply pretension to achieve a certain stiffness. Therefore, firstly the form-state design is carried out based on the force density equation of cable membrane structure to make it meet the requirement of the shape and accuracy under its own pretension and external load. The tension of cable membrane structure will lead to truss deformation, and after rebalancing, resulting in the reduction of shape accuracy of cable membrane reflector and unreasonable tension distribution. Therefore, it is necessary to establish the nonlinear finite element model for the whole antenna. By iteratively modifying the antenna model, the tension design variables and configuration of deployable antenna are obtained. The present method is programmed for a corresponding example at last, and the results indicate that the method is feasible.
2024, 43(4): 721-728.
doi: 10.13433/j.cnki.1003-8728.20220259
Abstract:
Aiming at the typical deadlock problem of U-shaped obstacles when applying traditional ant colony algorithm in mobile robot path planning, an improved ant colony algorithm with multi-directional and multi-layer filling of U-shaped obstacles is proposed. Firstly, it is proved that the optimal solution of path planning will not enter the U-shaped obstacles; Secondly, it is proved that the multi-directional and multi-layer filling method can fill U-shaped obstacles to solve the deadlock problem without blocking the original path, which has the retention of the original path and has less filling iteration times and total iteration time; After that, the number of iterations of the filling graph is theoretically determined. This filling method is not only suitable for U-shaped obstacles, but also suitable for other filling areas, and it can completely fill the fillable areas; Finally, this filling method is combined with ant colony algorithm to realize mobile robot path planning. The simulation results show that the improved ant colony algorithm is more efficient than the traditional ant colony algorithm.
Aiming at the typical deadlock problem of U-shaped obstacles when applying traditional ant colony algorithm in mobile robot path planning, an improved ant colony algorithm with multi-directional and multi-layer filling of U-shaped obstacles is proposed. Firstly, it is proved that the optimal solution of path planning will not enter the U-shaped obstacles; Secondly, it is proved that the multi-directional and multi-layer filling method can fill U-shaped obstacles to solve the deadlock problem without blocking the original path, which has the retention of the original path and has less filling iteration times and total iteration time; After that, the number of iterations of the filling graph is theoretically determined. This filling method is not only suitable for U-shaped obstacles, but also suitable for other filling areas, and it can completely fill the fillable areas; Finally, this filling method is combined with ant colony algorithm to realize mobile robot path planning. The simulation results show that the improved ant colony algorithm is more efficient than the traditional ant colony algorithm.
2024, 43(4): 729-736.
doi: 10.13433/j.cnki.1003-8728.20220289
Abstract:
To overcome the singularity and inadequate smoothness of the exit section in the original deflection control system of the axisymmetric vector exhaust nozzle, a new translation control scheme is developed. CATIA is used to create a 3D model for the axisymmetric vector exhaust nozzle translation control system, and the motion simulation is conducted in the DMU module, with the sensor activated to track the drive servo's rotation angle data. The spatial kinematic equations are established for numerical calculation, curve fitting, and error analysis, and the 3D model dimensional data and restrictions are substituted into MATLAB. The dynamic control commands were generated with a two-dimensional interpolation model describing the mapping relationship between the nozzle vector deflection angle, the vector azimuth angle, and the rudder rotation angle. The simulation results show that the translation control scheme has no singular positions and a good exit cross-section shape, which improves the nozzle's reliability and sealing while also meeting the demand for accurate control of axisymmetric vector exhaust nozzles. At last, the model prototype confirms the feasibility of the translation control scheme.
To overcome the singularity and inadequate smoothness of the exit section in the original deflection control system of the axisymmetric vector exhaust nozzle, a new translation control scheme is developed. CATIA is used to create a 3D model for the axisymmetric vector exhaust nozzle translation control system, and the motion simulation is conducted in the DMU module, with the sensor activated to track the drive servo's rotation angle data. The spatial kinematic equations are established for numerical calculation, curve fitting, and error analysis, and the 3D model dimensional data and restrictions are substituted into MATLAB. The dynamic control commands were generated with a two-dimensional interpolation model describing the mapping relationship between the nozzle vector deflection angle, the vector azimuth angle, and the rudder rotation angle. The simulation results show that the translation control scheme has no singular positions and a good exit cross-section shape, which improves the nozzle's reliability and sealing while also meeting the demand for accurate control of axisymmetric vector exhaust nozzles. At last, the model prototype confirms the feasibility of the translation control scheme.
