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RSS2023 Vol. 42, No. 8
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2023, 42(8): 1171-1177.
doi: 10.13433/j.cnki.1003-8728.20220047
PDF 7008KB
Abstract:
Diaphragm air pump will produce vibration during operation. The constrained damping gasket (SCDG) can effectively reduce the vibration of the diaphragm air pump. A SCDG is designed and prepared in this paper, in which the aluminum alloys as the constrained layer and the viscoelastic materials as the damping layer. The vibration response of the diaphragm air pump with and without SCDG was compared through the time-domain and frequency-domain response. It is found that the SCDG can achieve good damping effect with 4 mm (or 1/10 thickness of traditional gaskets) as the thickness, thus improving the stability of the system. At the same time, the damping mechanism of SCDG is analyzed from the aspects of material and structure.
Diaphragm air pump will produce vibration during operation. The constrained damping gasket (SCDG) can effectively reduce the vibration of the diaphragm air pump. A SCDG is designed and prepared in this paper, in which the aluminum alloys as the constrained layer and the viscoelastic materials as the damping layer. The vibration response of the diaphragm air pump with and without SCDG was compared through the time-domain and frequency-domain response. It is found that the SCDG can achieve good damping effect with 4 mm (or 1/10 thickness of traditional gaskets) as the thickness, thus improving the stability of the system. At the same time, the damping mechanism of SCDG is analyzed from the aspects of material and structure.
2023, 42(8): 1178-1183.
doi: 10.13433/j.cnki.1003-8728.20220054
Abstract:
In order to study the vibration transmission of hydraulic host-arc gate, the effective vibration suppression measures are put forward. In this paper, through the establishment of the three-dimensional entity model, the dynamic equation of hydraulic host-arc gate is established, and the stiffness damping characteristics of the hydraulic oil is theoretically analyzed. Taking the hydraulic system as the vibration source, the hydraulic hoist-coupling dynamics simulation model of radial gate is established in Simpack, and parameters of the base partition damper and gate partition damper are optimized to suppress the system vibration. The results showed that: The base partition damper and gate partition damper can effectively suppress vibration transmission, and the dominant range of stiffness and damping of the two dampers is obtained, where the base partition damper stiffness is 1 × 104-1 × 105 N/mm, and the damping is 100-2 000 Ns/mm; the rigidity of the gate partition damper is 1 × 104-5×105 N/mm, and the damping is 100-2 000 Ns/mm.
In order to study the vibration transmission of hydraulic host-arc gate, the effective vibration suppression measures are put forward. In this paper, through the establishment of the three-dimensional entity model, the dynamic equation of hydraulic host-arc gate is established, and the stiffness damping characteristics of the hydraulic oil is theoretically analyzed. Taking the hydraulic system as the vibration source, the hydraulic hoist-coupling dynamics simulation model of radial gate is established in Simpack, and parameters of the base partition damper and gate partition damper are optimized to suppress the system vibration. The results showed that: The base partition damper and gate partition damper can effectively suppress vibration transmission, and the dominant range of stiffness and damping of the two dampers is obtained, where the base partition damper stiffness is 1 × 104-1 × 105 N/mm, and the damping is 100-2 000 Ns/mm; the rigidity of the gate partition damper is 1 × 104-5×105 N/mm, and the damping is 100-2 000 Ns/mm.
2023, 42(8): 1184-1191.
doi: 10.13433/j.cnki.1003-8728.20220052
Abstract:
Rolling body in the process of manufacturing is often affected by the precision of the grinding equipment, grinding disc parameters and groove shape, processing parameters (pressure, speed, etc.) and "error reflection" phenomenon and other factors, and there is a certain diameter error, coupled with the bearing assembly may have several rolling bodies with different diameter error mixed. It is of great significance to study the influence of rolling body diameter error on bearing noise. This study takes D17621N4Q double half inner ring angular contact ball bearing as an example, through the design of experiments to collect the noise signal under different diameter error and arrangement mode working condition, respectively extract the signal effective sound pressure and wavelet packet-AR energy entropy two characteristic parameters, and two aspects from the noise signal strength and confusion degree are analysed. The experimental results show that the size and number of error rolling elements as well as different arrangement methods will affect the noise characteristics of rolling bearings in a certain way, and the reasonable arrangement of error rolling elements can effectively reduce the operation noise of rolling bearings.
Rolling body in the process of manufacturing is often affected by the precision of the grinding equipment, grinding disc parameters and groove shape, processing parameters (pressure, speed, etc.) and "error reflection" phenomenon and other factors, and there is a certain diameter error, coupled with the bearing assembly may have several rolling bodies with different diameter error mixed. It is of great significance to study the influence of rolling body diameter error on bearing noise. This study takes D17621N4Q double half inner ring angular contact ball bearing as an example, through the design of experiments to collect the noise signal under different diameter error and arrangement mode working condition, respectively extract the signal effective sound pressure and wavelet packet-AR energy entropy two characteristic parameters, and two aspects from the noise signal strength and confusion degree are analysed. The experimental results show that the size and number of error rolling elements as well as different arrangement methods will affect the noise characteristics of rolling bearings in a certain way, and the reasonable arrangement of error rolling elements can effectively reduce the operation noise of rolling bearings.
2023, 42(8): 1192-1199.
doi: 10.13433/j.cnki.1003-8728.20220075
Abstract:
To perform contact analysis of rough surface with Greenwood-Williamson (GW) model, both the asperity identification scheme based method and spectral moment approach on the basis of random process theory are widely used for the calculation of asperity distribution parameters. In order to clarify the difference in contact solution caused by the application of the two methods, rough surface samples with various statistical distributions are randomly generated by using Fast Fourier Transformation. Asperity peak distribution parameters of the simulated samples are determined by using three-point definition and spectral moment approach, respectively. Contact analysis of the samples are carried out by using GW model with the two methods. The calculated results are compared and the effects of the statistical distribution parameters, high pass filtering, radius of curvature and load are discussed. Finally, the experimental data are used to inspect the deviation of spectral moment approach. Suggestions for calculating the asperity distribution parameters are provided.
To perform contact analysis of rough surface with Greenwood-Williamson (GW) model, both the asperity identification scheme based method and spectral moment approach on the basis of random process theory are widely used for the calculation of asperity distribution parameters. In order to clarify the difference in contact solution caused by the application of the two methods, rough surface samples with various statistical distributions are randomly generated by using Fast Fourier Transformation. Asperity peak distribution parameters of the simulated samples are determined by using three-point definition and spectral moment approach, respectively. Contact analysis of the samples are carried out by using GW model with the two methods. The calculated results are compared and the effects of the statistical distribution parameters, high pass filtering, radius of curvature and load are discussed. Finally, the experimental data are used to inspect the deviation of spectral moment approach. Suggestions for calculating the asperity distribution parameters are provided.
2023, 42(8): 1200-1206.
doi: 10.13433/j.cnki.1003-8728.20220034
Abstract:
Inspired by the deformation mechanism of honeybee abdomen, this paper designed a bionic morphing mechanism that can achieve expansion and bending. The morphing mechanism adopted three groups of RSH/RRR branch chains in parallel. The screw theory was used to calculate the degree of freedom of the morphing mechanism. The results show that the kinematic degree of freedom of the morphing mechanism meets the deformation requirements of the morphing nose cone and can be used as its deformation expanding skeleton. Then the dynamic performance of the variant mechanism was simulated and analyzed. The results show that the deformation of the variant mechanism can meet the design requirements and that it can still maintain a relatively stable motion state under load condition. The dynamic performance of the morphing nose cone is good. The variant mechanism can improve the flexibility and adaptability of the morphing nose cone. Meanwhile, the self-locking characteristic and the parallel distribution of three groups of branch chains of the morphing mechanism enhance the stability of the morphing nose cone.
Inspired by the deformation mechanism of honeybee abdomen, this paper designed a bionic morphing mechanism that can achieve expansion and bending. The morphing mechanism adopted three groups of RSH/RRR branch chains in parallel. The screw theory was used to calculate the degree of freedom of the morphing mechanism. The results show that the kinematic degree of freedom of the morphing mechanism meets the deformation requirements of the morphing nose cone and can be used as its deformation expanding skeleton. Then the dynamic performance of the variant mechanism was simulated and analyzed. The results show that the deformation of the variant mechanism can meet the design requirements and that it can still maintain a relatively stable motion state under load condition. The dynamic performance of the morphing nose cone is good. The variant mechanism can improve the flexibility and adaptability of the morphing nose cone. Meanwhile, the self-locking characteristic and the parallel distribution of three groups of branch chains of the morphing mechanism enhance the stability of the morphing nose cone.
2023, 42(8): 1207-1212.
doi: 10.13433/j.cnki.1003-8728.20230277
Abstract:
In the past, most of the studies on the joint stiffness characteristics focused on the transverse comparison of the joint with different roughness, less or ignored the longitudinal comparison of the stiffness characteristics of the same joint before and after loading with multiple cyclic loading, and the longitudinal comparison of the change of height of some micro convex bodies change before and after loading with multiple cyclic loading. In fact, both stiffness and height of some micro convex bodies will change under multiple load cycles, which makes it more complex to predict the dynamic and static performance of the equipment. In order to solve this problem, the variation law of the stiffness characteristics of the bolt joint of rough surface element under the cyclic load history based on experiments is studied. In order to quantitatively study and better apply this law, the load history curves are fitted. The longitudinal comparative study shows that the stiffness characteristics of the element joint change with the change of the load cycle times, that is, with the increasing of load history, the deformation of the element bolt joint decreases, and the joint stiffness increases. In order to further understand the mechanism of the change in stiffness characteristics, the microscopic observation of the contact surface of the joint before and after the load is also carried out. It is found that the height of the micro convex body of the surface near the bolt hole of the joint has the different degrees of plastic deformation under the repeated cyclic preload of the bolt.
In the past, most of the studies on the joint stiffness characteristics focused on the transverse comparison of the joint with different roughness, less or ignored the longitudinal comparison of the stiffness characteristics of the same joint before and after loading with multiple cyclic loading, and the longitudinal comparison of the change of height of some micro convex bodies change before and after loading with multiple cyclic loading. In fact, both stiffness and height of some micro convex bodies will change under multiple load cycles, which makes it more complex to predict the dynamic and static performance of the equipment. In order to solve this problem, the variation law of the stiffness characteristics of the bolt joint of rough surface element under the cyclic load history based on experiments is studied. In order to quantitatively study and better apply this law, the load history curves are fitted. The longitudinal comparative study shows that the stiffness characteristics of the element joint change with the change of the load cycle times, that is, with the increasing of load history, the deformation of the element bolt joint decreases, and the joint stiffness increases. In order to further understand the mechanism of the change in stiffness characteristics, the microscopic observation of the contact surface of the joint before and after the load is also carried out. It is found that the height of the micro convex body of the surface near the bolt hole of the joint has the different degrees of plastic deformation under the repeated cyclic preload of the bolt.
2023, 42(8): 1213-1220.
doi: 10.13433/j.cnki.1003-8728.20220067
Abstract:
In the process of robot design, the robot workspace needs to be calculated repeatedly, so it is of great significance to improve the computational efficiency and accuracy of the workspace. An improved method to solve the problems of low precision and slow speed of the traditional method is proposed. The seed space is generated by the traditional method and discretized into multiple subspaces, the normal distribution is used to expand the subspace with insufficient number of workspace points, and the normal distribution parameters are adjusted according to the positions of the expanded workspace points to obtain the reachable workspace. Then, the operability value to evaluate the flexibility of the robot is used, the flexible seed space from the reachable workspace is filtered out, and the normal distribution of adjustable parameters to expand the boundary of the flexible seed space to obtain a flexible workspace is used. By taking the 6-axis robot as an example to simulate and analyze the improved method, the results show that the present method can greatly improve the solving efficiency on the premise of ensuring the solving accuracy, and provide convenience for the subsequent optimization design of the robot.
In the process of robot design, the robot workspace needs to be calculated repeatedly, so it is of great significance to improve the computational efficiency and accuracy of the workspace. An improved method to solve the problems of low precision and slow speed of the traditional method is proposed. The seed space is generated by the traditional method and discretized into multiple subspaces, the normal distribution is used to expand the subspace with insufficient number of workspace points, and the normal distribution parameters are adjusted according to the positions of the expanded workspace points to obtain the reachable workspace. Then, the operability value to evaluate the flexibility of the robot is used, the flexible seed space from the reachable workspace is filtered out, and the normal distribution of adjustable parameters to expand the boundary of the flexible seed space to obtain a flexible workspace is used. By taking the 6-axis robot as an example to simulate and analyze the improved method, the results show that the present method can greatly improve the solving efficiency on the premise of ensuring the solving accuracy, and provide convenience for the subsequent optimization design of the robot.
2023, 42(8): 1221-1228.
doi: 10.13433/j.cnki.1003-8728.20220081
Abstract:
To meet the requirements of a lightweight vehicle side door latch and its effective space utilization, the configuration scheme of its over-constrainedspatial mechanism is proposed based on its position and orientation characteristics. The mechanismsfor decoupling feature synthesis are carried out for its topology and dimensional constraint types, and two clusters of mutually perpendicular rotational pairs are constructed (\begin{document}$\{R_A\|R_B\| R_F \perp R_E\|R_C\| R_D\} $\end{document} ![]()
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To meet the requirements of a lightweight vehicle side door latch and its effective space utilization, the configuration scheme of its over-constrainedspatial mechanism is proposed based on its position and orientation characteristics. The mechanismsfor decoupling feature synthesis are carried out for its topology and dimensional constraint types, and two clusters of mutually perpendicular rotational pairs are constructed (
2023, 42(8): 1229-1235.
doi: 10.13433/j.cnki.1003-8728.20220245
Abstract:
In order to solve the complex problem of cavitation in axial piston pump, the motion law of pump is introduced, and the models for piston cavity pressure, pump inlet and outlet flow and swashplate torque are established respectively, taking the pressure in piston cavity and oil outlet flow as the benchmark, orthogonal test, Kriging surface interpolation and genetic particle swarm optimization algorithm are used to calculate the air content of hydraulic oil, oil inlet pressure gradient. The piston speed and piston diameter are optimized. The test shows that the significant values of air content in oil, piston speed and piston diameter on chamber pressure and oil outlet flow are below 0.05. When the piston speed is 700 r/min, piston diameter is 8mm and air content in oil is 3%, the pressure in piston chamber and oil outlet flow are 47991 Pa and 2.1 L/min respectively.The optimal results are introduced into the model for Amesim single piston pump. The negative pressure in the piston chamber is −29573.5 Pa, the flow rate at the oil outlet is 2.18 L/min, and no cavitation occurs, the superiority of the control algorithm is verified, which provides a reference for preventing the occurrence of cavity in axial piston pump.
In order to solve the complex problem of cavitation in axial piston pump, the motion law of pump is introduced, and the models for piston cavity pressure, pump inlet and outlet flow and swashplate torque are established respectively, taking the pressure in piston cavity and oil outlet flow as the benchmark, orthogonal test, Kriging surface interpolation and genetic particle swarm optimization algorithm are used to calculate the air content of hydraulic oil, oil inlet pressure gradient. The piston speed and piston diameter are optimized. The test shows that the significant values of air content in oil, piston speed and piston diameter on chamber pressure and oil outlet flow are below 0.05. When the piston speed is 700 r/min, piston diameter is 8mm and air content in oil is 3%, the pressure in piston chamber and oil outlet flow are 47991 Pa and 2.1 L/min respectively.The optimal results are introduced into the model for Amesim single piston pump. The negative pressure in the piston chamber is −29573.5 Pa, the flow rate at the oil outlet is 2.18 L/min, and no cavitation occurs, the superiority of the control algorithm is verified, which provides a reference for preventing the occurrence of cavity in axial piston pump.
2023, 42(8): 1236-1241.
doi: 10.13433/j.cnki.1003-8728.20220032
Abstract:
The claw-type hydrogen circulation pump is the key equipment of a fuel cell system, which has the advantages of stable gas transmission, wide operating range and high efficiency. In this paper, the mathematical model of the hydrogen circulation pump is established, its internal flow characteristics are numerically simulated, and the flow field distribution law in its working chamber is obtained. The results show that there is an equal-volume conveyance process in the working process of the rotor of the circulation pump. The gas pressure and temperature in the two working cavities are different, and the leakage leads to higher pressure in the working chamber with smaller volume, with the pressure difference being about 8.1 kPa.The pressure increases with the increase of clearance, suction and discharge pressure; the temperature decreases with the increase of suction pressure. The maximum thermal deformation of the rotor is located at the rotor's claw tip.The simulation results are basically consistent with the experimental values, thus verifying the accuracy of the simulation method.
The claw-type hydrogen circulation pump is the key equipment of a fuel cell system, which has the advantages of stable gas transmission, wide operating range and high efficiency. In this paper, the mathematical model of the hydrogen circulation pump is established, its internal flow characteristics are numerically simulated, and the flow field distribution law in its working chamber is obtained. The results show that there is an equal-volume conveyance process in the working process of the rotor of the circulation pump. The gas pressure and temperature in the two working cavities are different, and the leakage leads to higher pressure in the working chamber with smaller volume, with the pressure difference being about 8.1 kPa.The pressure increases with the increase of clearance, suction and discharge pressure; the temperature decreases with the increase of suction pressure. The maximum thermal deformation of the rotor is located at the rotor's claw tip.The simulation results are basically consistent with the experimental values, thus verifying the accuracy of the simulation method.
2023, 42(8): 1242-1248.
doi: 10.13433/j.cnki.1003-8728.20220065
Abstract:
The manufacturing errors of the hydrostatic bearing throttle aperture d0, bearing radius clearance h0, oil cavity length L and oil cavity width B of the precision machine tool spindleare analyzed, and the throttle aperture d0 and radius clearance h0 that have a greater impact on manufacturing errors as the object are selected. A calculation model for hydrostatic bearing performance considering the throttle aperture error εd and radius clearance error εh is established. The bearing stiffness J and rotation accuracy e under the influence of εd and εh are calculated and analyzed, and the theoretical analysis results are verified by experiments.The research results show that the influence of manufacturing error εd and εh on J increases with the increase of load W. When W is 600 N and εd is 0.05 mm, the value of J is 1.34 times that when εd is −0.05 mm, and εh is 10 μm. The J value at εh is only 29.9% when εh is −10 μm; for e, εd will bring about 1 μm, and εh will increase about 2 μm influence.
The manufacturing errors of the hydrostatic bearing throttle aperture d0, bearing radius clearance h0, oil cavity length L and oil cavity width B of the precision machine tool spindleare analyzed, and the throttle aperture d0 and radius clearance h0 that have a greater impact on manufacturing errors as the object are selected. A calculation model for hydrostatic bearing performance considering the throttle aperture error εd and radius clearance error εh is established. The bearing stiffness J and rotation accuracy e under the influence of εd and εh are calculated and analyzed, and the theoretical analysis results are verified by experiments.The research results show that the influence of manufacturing error εd and εh on J increases with the increase of load W. When W is 600 N and εd is 0.05 mm, the value of J is 1.34 times that when εd is −0.05 mm, and εh is 10 μm. The J value at εh is only 29.9% when εh is −10 μm; for e, εd will bring about 1 μm, and εh will increase about 2 μm influence.
2023, 42(8): 1249-1260.
doi: 10.13433/j.cnki.1003-8728.20220080
Abstract:
In recent years, intelligent manufacturing has become an important direction for the development of manufacturing industry. Digital Twin, as an enabling technology to practice the concept and targets of intelligent manufacturing, provides the effective means to solve the cyber-physical integration in the intelligent manufacturing, which has received the extensive attention in the world. In order to comprehensively analyze the research states and development trends of the digital twin technology in the intelligent manufacturing, according to the data sources of Web of Science (WoS) and China National Knowledge Infrastructure (CNKI), CiteSpace5.7 is used to sort out the publications from 2011 to 2021 at home and abroad. The map of scientific knowledge is drawn and analyzed qualitatively and quantitatively from different dimensions, such as literature characteristics, scientific research cooperation, research hotspots and frontiers. Finally, the development tendency of digital twin technology in the intelligent manufacturing is prospected from the angles of technology and application.
In recent years, intelligent manufacturing has become an important direction for the development of manufacturing industry. Digital Twin, as an enabling technology to practice the concept and targets of intelligent manufacturing, provides the effective means to solve the cyber-physical integration in the intelligent manufacturing, which has received the extensive attention in the world. In order to comprehensively analyze the research states and development trends of the digital twin technology in the intelligent manufacturing, according to the data sources of Web of Science (WoS) and China National Knowledge Infrastructure (CNKI), CiteSpace5.7 is used to sort out the publications from 2011 to 2021 at home and abroad. The map of scientific knowledge is drawn and analyzed qualitatively and quantitatively from different dimensions, such as literature characteristics, scientific research cooperation, research hotspots and frontiers. Finally, the development tendency of digital twin technology in the intelligent manufacturing is prospected from the angles of technology and application.
2023, 42(8): 1261-1269.
doi: 10.13433/j.cnki.1003-8728.20220082
Abstract:
A compression packer is widely used in an oilfield’s stratified production processes, and the setting of its rubber cylinder is achieved by compressing the rubber cylinder or pipe string through the action of high-pressure fluid on the piston. Field operations find that the rubber cylinder is far from the load end and that the majority of it are loaded in one direction, resulting in incomplete setting and low contact stress and sealing performance coefficient. Due to the above problems, based on the Mooney-Rivlin hyper-elastic model, the hose deformation and contact nonlinear theory, the finite element model for calculating the compression rubber cylinder group was established, and the single factor analysis was carried out from the inner bushing and the anti-shoulder structure, and the open-hole sealing was carried out. The performance is studied, and the results show that: 1） the triangular inner bushing can effectively improve the contact stress in the middle of the rubber cylinder; 2） the metal ring anti-burst structure can improve the sealing performance coefficient of the rubber cylinder; 3） compared with the conventional compression packer, the sealing performance of the optimized compression packer is significantly improved; 4） when the irregularity of the open hole wall is within a certain range, the sealing performance of the compression packer is not affected much.
A compression packer is widely used in an oilfield’s stratified production processes, and the setting of its rubber cylinder is achieved by compressing the rubber cylinder or pipe string through the action of high-pressure fluid on the piston. Field operations find that the rubber cylinder is far from the load end and that the majority of it are loaded in one direction, resulting in incomplete setting and low contact stress and sealing performance coefficient. Due to the above problems, based on the Mooney-Rivlin hyper-elastic model, the hose deformation and contact nonlinear theory, the finite element model for calculating the compression rubber cylinder group was established, and the single factor analysis was carried out from the inner bushing and the anti-shoulder structure, and the open-hole sealing was carried out. The performance is studied, and the results show that: 1） the triangular inner bushing can effectively improve the contact stress in the middle of the rubber cylinder; 2） the metal ring anti-burst structure can improve the sealing performance coefficient of the rubber cylinder; 3） compared with the conventional compression packer, the sealing performance of the optimized compression packer is significantly improved; 4） when the irregularity of the open hole wall is within a certain range, the sealing performance of the compression packer is not affected much.
2023, 42(8): 1270-1276.
doi: 10.13433/j.cnki.1003-8728.20220099
Abstract:
The thermal expansion and cold shrinkage of thermoplastic materials in FDM (Fused deposition modeling) process is an important factor affecting the dimensional accuracy of 3D printed parts. The influence of the printing parameters on the dimensional accuracy of polymer spur gear was studied by using orthogonal experiment with four printing parameters as control variables, including layer thickness, nozzle temperature, printing speed and bed temperature. Three-dimensional scanning technology was used to measure the printed polymer spur gears, and the deformation characteristics of each gear were analyzed, thereby determining the tooth profile deviation of the polymer spur gears. The pitch deviation was measured by pitch meter. The influence order of the printing parameters on the tooth profile deviation and pitch deviation was analyzed by using the range method. Finally, the optimal combination of printing parameters obtained by using the comprehensive balance method is as follows: nozzle temperature is 230 ℃, bed temperature is 87 ℃, printing speed is 40 mm/s, and layer thickness is 0.1 mm.
The thermal expansion and cold shrinkage of thermoplastic materials in FDM (Fused deposition modeling) process is an important factor affecting the dimensional accuracy of 3D printed parts. The influence of the printing parameters on the dimensional accuracy of polymer spur gear was studied by using orthogonal experiment with four printing parameters as control variables, including layer thickness, nozzle temperature, printing speed and bed temperature. Three-dimensional scanning technology was used to measure the printed polymer spur gears, and the deformation characteristics of each gear were analyzed, thereby determining the tooth profile deviation of the polymer spur gears. The pitch deviation was measured by pitch meter. The influence order of the printing parameters on the tooth profile deviation and pitch deviation was analyzed by using the range method. Finally, the optimal combination of printing parameters obtained by using the comprehensive balance method is as follows: nozzle temperature is 230 ℃, bed temperature is 87 ℃, printing speed is 40 mm/s, and layer thickness is 0.1 mm.
2023, 42(8): 1277-1284.
doi: 10.13433/j.cnki.1003-8728.20220055
Abstract:
In order to solve the problems of ambiguity, complexity, and subjectivity in the previous extraction process of automobile styling design elements, this study uses extension comprehensive evaluation to extract perceptually the key design elements of the front face of the automobile. First, starting from the user's perceptual cognition information on the front face of the car, the inferential perceptual engineering is used to establish a perceptual evaluation index system. Secondly, the subjective and objective weights of each perceptual index are obtained through fuzzy analytic hierarchy process and entropy weight method, and the comprehensive weight is obtained. Then, extension theory is used to evaluate the importance of car front face design elements for each perceptual index. Finally, according to the weight of each index and the evaluation results of design elements, the degree of importance of the design elements affecting the front face of the car is comprehensively determined. The process of this research method is simple and logical, which not only enhances the objective science of extracting key design elements of the front face of the car, but also provides an effective reference for the extraction of key design elements of other products.
In order to solve the problems of ambiguity, complexity, and subjectivity in the previous extraction process of automobile styling design elements, this study uses extension comprehensive evaluation to extract perceptually the key design elements of the front face of the automobile. First, starting from the user's perceptual cognition information on the front face of the car, the inferential perceptual engineering is used to establish a perceptual evaluation index system. Secondly, the subjective and objective weights of each perceptual index are obtained through fuzzy analytic hierarchy process and entropy weight method, and the comprehensive weight is obtained. Then, extension theory is used to evaluate the importance of car front face design elements for each perceptual index. Finally, according to the weight of each index and the evaluation results of design elements, the degree of importance of the design elements affecting the front face of the car is comprehensively determined. The process of this research method is simple and logical, which not only enhances the objective science of extracting key design elements of the front face of the car, but also provides an effective reference for the extraction of key design elements of other products.
2023, 42(8): 1285-1292.
doi: 10.13433/j.cnki.1003-8728.20220051
Abstract:
There are many factors affecting the accuracy of machine tools, among which the error caused by workpiece load can not be ignored. Through the macro statics analysis of the loading condition of the machine tool, the positioning error and other geometric errors of the machine tool are measured by using the laser interferometer. The results show that the workpiece load has the significant influence on the geometric error of the machine tool, especially in the positioning accuracy, the difference between the load of 100 kg and the no-load is about 10%, and after the error compensation, the difference will be increased to about 40%. Therefore, the positioning error compensation method combined with the load is proposed. This method solves the problem of under compensation or over compensation of pitch error compensation in actual working conditions, and provides theoretical guidance for further improving the positioning accuracy of machine tool in working conditions.
There are many factors affecting the accuracy of machine tools, among which the error caused by workpiece load can not be ignored. Through the macro statics analysis of the loading condition of the machine tool, the positioning error and other geometric errors of the machine tool are measured by using the laser interferometer. The results show that the workpiece load has the significant influence on the geometric error of the machine tool, especially in the positioning accuracy, the difference between the load of 100 kg and the no-load is about 10%, and after the error compensation, the difference will be increased to about 40%. Therefore, the positioning error compensation method combined with the load is proposed. This method solves the problem of under compensation or over compensation of pitch error compensation in actual working conditions, and provides theoretical guidance for further improving the positioning accuracy of machine tool in working conditions.
2023, 42(8): 1293-1315.
doi: 10.13433/j.cnki.1003-8728.20220086
Abstract:
Texture surface defect detection is meaningful and challenging in the field of machine vision. The history of texture surface defect detection can be traced back to the middle to late 20th century. Moreover, in recent years, with the flourishing development of deep learning technology, texture surface defect detection technology had a big leap. However, so far, there are still few surveys and reviews of texture surface defect detection. Against such a background, we comprehensively reviewed more than 200 papers about texture surface defect detection with machine vision from 2017 to 2021 and made a timely and comprehensive investigation of its research progress. This paper reviews the development history and latest research progress of texture surface defect detection. In principle, the methods of texture surface defect detection by machine vision are divided into the traditional method and the deep learning method, which were studied and analyzed deeply, especially the deep learning method. The paper summarizes several methods of texture surface defect detection by machine vision that appeared recently and reviews the research progress of these methods. Finally, it introduced the future research trends to provide enlightenment for further studies.
Texture surface defect detection is meaningful and challenging in the field of machine vision. The history of texture surface defect detection can be traced back to the middle to late 20th century. Moreover, in recent years, with the flourishing development of deep learning technology, texture surface defect detection technology had a big leap. However, so far, there are still few surveys and reviews of texture surface defect detection. Against such a background, we comprehensively reviewed more than 200 papers about texture surface defect detection with machine vision from 2017 to 2021 and made a timely and comprehensive investigation of its research progress. This paper reviews the development history and latest research progress of texture surface defect detection. In principle, the methods of texture surface defect detection by machine vision are divided into the traditional method and the deep learning method, which were studied and analyzed deeply, especially the deep learning method. The paper summarizes several methods of texture surface defect detection by machine vision that appeared recently and reviews the research progress of these methods. Finally, it introduced the future research trends to provide enlightenment for further studies.
2023, 42(8): 1316-1323.
doi: 10.13433/j.cnki.1003-8728.20220058
Abstract:
To address the problem of low diagnostic accuracy caused by samples satisfying independent identical distribution in machine learning methods, in this paper, we propose a bearing fault transfer diagnosis method combining the balanced distribution adaptive algorithm and the K-nearest neighbor classification algorithm. Firstly, the time domain features of the bearing fault signals under variable operating conditions are extracted as the source and target domains, respectively, the Fisher discriminant analysis method is used to prefer the features. Secondly, the feature samples of different working conditions are mapped to the reproducible Hilbert space based on balanced distribution adaptive, the maximum mean discrepancy is introduced to adapt the edge distribution discrepancy and conditional distribution discrepancy of the variable working condition samples. Finally, the K-nearest neighbor classifier is used to perform migration diagnosis on the samples after the distribution adaptation. Simulation and experimental validation show that the accuracy and distribution distance of the bearing diagnosis of the proposed method are significantly advantageous compared with other algorithms on both same-experimental platform and cross-experimental platform transference.
To address the problem of low diagnostic accuracy caused by samples satisfying independent identical distribution in machine learning methods, in this paper, we propose a bearing fault transfer diagnosis method combining the balanced distribution adaptive algorithm and the K-nearest neighbor classification algorithm. Firstly, the time domain features of the bearing fault signals under variable operating conditions are extracted as the source and target domains, respectively, the Fisher discriminant analysis method is used to prefer the features. Secondly, the feature samples of different working conditions are mapped to the reproducible Hilbert space based on balanced distribution adaptive, the maximum mean discrepancy is introduced to adapt the edge distribution discrepancy and conditional distribution discrepancy of the variable working condition samples. Finally, the K-nearest neighbor classifier is used to perform migration diagnosis on the samples after the distribution adaptation. Simulation and experimental validation show that the accuracy and distribution distance of the bearing diagnosis of the proposed method are significantly advantageous compared with other algorithms on both same-experimental platform and cross-experimental platform transference.
2023, 42(8): 1324-1331.
doi: 10.13433/j.cnki.1003-8728.20230266
Abstract:
Aiming at the typical time delay problem in the continuous damping adjustable suspension system, a cloud-based over-the-horizon preview control strategy is proposed in this paper. First, MATLAB/Simulink is used to build the vehicle dynamics model of the 7 DOF continuous damping suspension system; then, the cloud server is used to build the over-the-horizon preview control strategy operation platform, and the MQTT (Message queuing telemetry transport) is used to connect the vehicle control unit and the cloud server to the IoT platform to realize the data communication between the cloud control strategy and the vehicle control unit. Finally, the Carsim-Simulink co-simulation model and the vehicle control unit are used to conduct hardware-in-the-loop tests. The results show that the proposed control strategy can not only improve the ride comfort of the suspension system, but also can effectively reduce the load of the vehicle electronic control unit by deploying the preview control strategy in the cloud.
Aiming at the typical time delay problem in the continuous damping adjustable suspension system, a cloud-based over-the-horizon preview control strategy is proposed in this paper. First, MATLAB/Simulink is used to build the vehicle dynamics model of the 7 DOF continuous damping suspension system; then, the cloud server is used to build the over-the-horizon preview control strategy operation platform, and the MQTT (Message queuing telemetry transport) is used to connect the vehicle control unit and the cloud server to the IoT platform to realize the data communication between the cloud control strategy and the vehicle control unit. Finally, the Carsim-Simulink co-simulation model and the vehicle control unit are used to conduct hardware-in-the-loop tests. The results show that the proposed control strategy can not only improve the ride comfort of the suspension system, but also can effectively reduce the load of the vehicle electronic control unit by deploying the preview control strategy in the cloud.
2023, 42(8): 1332-1339.
doi: 10.13433/j.cnki.1003-8728.20220076
Abstract:
The single-domain feature cannot fully reflect the operating state of check valve of the high-pressure diaphragm pump, and the high-dimensional feature set composed of multi-domain features will produce dimensional disasters, and the information redundancy leads to low recognition accuracy of the fault diagnosis model. To this end, a fault diagnosis method for check valve of high-pressure diaphragm pump based on KLPP(Kernel local preservation projection) and RELM(Regularized extreme learning machine) is proposed in this paper. First, the time domain, frequency domain and time-frequency domain features of check valve vibration signal are respectively extracted to construct a multi-domain feature set. Then, dimensionality reduction is performed on the constructed multi-domain feature set through the KLPP algorithm. Finally, a fault diagnosis model based on RELM is established to identify the operating status of check valve. The experimental results show that the detection accuracy of the fault diagnosis method based on multi-domain features is higher than that of the single-domain feature recognition method; KLPP reduces the multi-domain feature set, which can effectively eliminate information redundancy; the established RELM fault diagnosis model has a recognition accuracy of 98.89%, which can effectively identify the fault type of check valve of the high-pressure diaphragm pump.
The single-domain feature cannot fully reflect the operating state of check valve of the high-pressure diaphragm pump, and the high-dimensional feature set composed of multi-domain features will produce dimensional disasters, and the information redundancy leads to low recognition accuracy of the fault diagnosis model. To this end, a fault diagnosis method for check valve of high-pressure diaphragm pump based on KLPP(Kernel local preservation projection) and RELM(Regularized extreme learning machine) is proposed in this paper. First, the time domain, frequency domain and time-frequency domain features of check valve vibration signal are respectively extracted to construct a multi-domain feature set. Then, dimensionality reduction is performed on the constructed multi-domain feature set through the KLPP algorithm. Finally, a fault diagnosis model based on RELM is established to identify the operating status of check valve. The experimental results show that the detection accuracy of the fault diagnosis method based on multi-domain features is higher than that of the single-domain feature recognition method; KLPP reduces the multi-domain feature set, which can effectively eliminate information redundancy; the established RELM fault diagnosis model has a recognition accuracy of 98.89%, which can effectively identify the fault type of check valve of the high-pressure diaphragm pump.
2023, 42(8): 1340-1348.
doi: 10.13433/j.cnki.1003-8728.20220070
Abstract:
Aiming at the characteristics of non-linear, non-stationary and large sample of rock fracture acoustic emission signals and the problem that traditional VMD and ITD algorithms have some limitations in denoising, an improved VMD-ITD joint denoising method is proposed. Taking tungsten rock as the research object, firstly, the component energy ratio is used as the termination condition of VMD, and rock fracture acoustic emission signal is decomposed into multiple IMF components. The mutual information between each component and original signal is used as the weighting factor of each component to reconstruct the signal, and then reconstructed signal is decomposed by ITD to achieve the purpose of secondary noise reduction. Finally, taking root mean square error and signal-to-noise ratio as the evaluation indexes,denoising effects of VMD, ITD and improved VMD-ITD joint denoising algorithm are compared and analyzed. Experiments show that improved VMD-ITD joint denoising algorithm has a root mean square error of 4.552 1 and a signal-to-noise ratio of 10.012 8. Compared with single VMD and ITD algorithms, it is better.
Aiming at the characteristics of non-linear, non-stationary and large sample of rock fracture acoustic emission signals and the problem that traditional VMD and ITD algorithms have some limitations in denoising, an improved VMD-ITD joint denoising method is proposed. Taking tungsten rock as the research object, firstly, the component energy ratio is used as the termination condition of VMD, and rock fracture acoustic emission signal is decomposed into multiple IMF components. The mutual information between each component and original signal is used as the weighting factor of each component to reconstruct the signal, and then reconstructed signal is decomposed by ITD to achieve the purpose of secondary noise reduction. Finally, taking root mean square error and signal-to-noise ratio as the evaluation indexes,denoising effects of VMD, ITD and improved VMD-ITD joint denoising algorithm are compared and analyzed. Experiments show that improved VMD-ITD joint denoising algorithm has a root mean square error of 4.552 1 and a signal-to-noise ratio of 10.012 8. Compared with single VMD and ITD algorithms, it is better.
2023, 42(8): 1349-1356.
doi: 10.13433/j.cnki.1003-8728.20220039
Abstract:
To optimize a naval ship's residential cabin layout and improve its design speed, the energy method is introduced into the NSGA-Ⅱgenetic algorithm and used to establish the mathematical model of the residential cabin layout, quantify specific requirements for the placement of accessories in the cabin and form the objective function for program selection. The MATLAB program is used to realize the algorithm's iterative calculation and automatic output of the layout scheme. Finally, a naval ship′s 20-person living cabin is taken as an example to verify the optimization. The experimental results show that the layout design speed is obviously improved, the layout scheme meets the requirements and improves the cabin layout utilization rate.
To optimize a naval ship's residential cabin layout and improve its design speed, the energy method is introduced into the NSGA-Ⅱgenetic algorithm and used to establish the mathematical model of the residential cabin layout, quantify specific requirements for the placement of accessories in the cabin and form the objective function for program selection. The MATLAB program is used to realize the algorithm's iterative calculation and automatic output of the layout scheme. Finally, a naval ship′s 20-person living cabin is taken as an example to verify the optimization. The experimental results show that the layout design speed is obviously improved, the layout scheme meets the requirements and improves the cabin layout utilization rate.
2023, 42(8): 1357-1361.
doi: 10.13433/j.cnki.1003-8728.20220048
Abstract:
Based on the Box-behnken design (BBD) test design method, the mechanical properties analysis of aluminum alloy clinched joints was carried out. Three kinds of aluminum alloy sheets 5182、5052 and 6061 were used in the test. A multivariate regression model with punching pressure, sheet thickness and sheet hardness as the influence factors and failure load as response value was established, and the model was verified via experiments. The results show that the multivariate regression model can accurately predict the tension-shear failure load of aluminum alloy clinched joints in a certain range of processing parameters, the maximum error is 17.7%, and the error is small in application. Variance analysis shows that the impact on the failure load is the largest in the order of punching pressure, followed by the sheet hardness and the sheet thickness. The failure load of the clinched joint firstly increases and then decreases with the increasing of punching pressure, and firstly decreases and then increases with the increasing of sheet thickness. The influence of the sheet hardness on the failure load of joint is positively linear correlation.
Based on the Box-behnken design (BBD) test design method, the mechanical properties analysis of aluminum alloy clinched joints was carried out. Three kinds of aluminum alloy sheets 5182、5052 and 6061 were used in the test. A multivariate regression model with punching pressure, sheet thickness and sheet hardness as the influence factors and failure load as response value was established, and the model was verified via experiments. The results show that the multivariate regression model can accurately predict the tension-shear failure load of aluminum alloy clinched joints in a certain range of processing parameters, the maximum error is 17.7%, and the error is small in application. Variance analysis shows that the impact on the failure load is the largest in the order of punching pressure, followed by the sheet hardness and the sheet thickness. The failure load of the clinched joint firstly increases and then decreases with the increasing of punching pressure, and firstly decreases and then increases with the increasing of sheet thickness. The influence of the sheet hardness on the failure load of joint is positively linear correlation.
2023, 42(8): 1362-1365.
doi: 10.13433/j.cnki.1003-8728.20220056
Abstract:
A large ultrasonic attenuation is found in water-squirting through-transmission ultrasonic C-scan detection of composite aramid paper honeycomb sandwich structure, which is caused by the defects of honeycomb collapse and cell bubbling. 3D finite element modeling simulation method is used to analyze and verify the influence of the honeycomb sandwich defects on the ultrasonic propagation in penetrating method. The propagation modes of ultrasonic wave in the integrity honeycomb, honeycomb with collapse and cell bubbling defects are simulated. The influences of the size and number of different defects on the amplitude of ultrasonic transmission wave are analyzed. The causes of the ultrasonic wave attenuation are discussed. The results of finite element simulation are consistent with those of the ultrasonic C scan test.
A large ultrasonic attenuation is found in water-squirting through-transmission ultrasonic C-scan detection of composite aramid paper honeycomb sandwich structure, which is caused by the defects of honeycomb collapse and cell bubbling. 3D finite element modeling simulation method is used to analyze and verify the influence of the honeycomb sandwich defects on the ultrasonic propagation in penetrating method. The propagation modes of ultrasonic wave in the integrity honeycomb, honeycomb with collapse and cell bubbling defects are simulated. The influences of the size and number of different defects on the amplitude of ultrasonic transmission wave are analyzed. The causes of the ultrasonic wave attenuation are discussed. The results of finite element simulation are consistent with those of the ultrasonic C scan test.
2023, 42(8): 1366-1372.
doi: 10.13433/j.cnki.1003-8728.20220084
Abstract:
This paper presents an experimental study on on-line monitoring of crack growth in metal structures under fatigue loading by using ultrasonic Lamb waves. An aluminum alloy plate structure with a central crack is manufactured and a network of piezoelectric wafers are mounted on the surface of the plate. During the process of fatigue test, piezoelectric wafers are used to excite and receive Lamb wave signals to monitor the fatigue crack growth behavior between the actuators and the sensors, mean-while, the crack length is observed in real-time. With time domain signal processing, the features of amplitude (AMP) and time of flight (ToF) features at the peak points of Lamb wave signals are extracted. An improved degree of health index and correspond-ing damage index are defined through Cauchy membership function, and their variations with the crack growth are evaluated. Finally, the DIs in all excitation-receive paths are fused by the damage presence probability imaging method to approximately characterize the variations of crack lengths, proving that the algorithm proposed in this paper is feasible and effective.
This paper presents an experimental study on on-line monitoring of crack growth in metal structures under fatigue loading by using ultrasonic Lamb waves. An aluminum alloy plate structure with a central crack is manufactured and a network of piezoelectric wafers are mounted on the surface of the plate. During the process of fatigue test, piezoelectric wafers are used to excite and receive Lamb wave signals to monitor the fatigue crack growth behavior between the actuators and the sensors, mean-while, the crack length is observed in real-time. With time domain signal processing, the features of amplitude (AMP) and time of flight (ToF) features at the peak points of Lamb wave signals are extracted. An improved degree of health index and correspond-ing damage index are defined through Cauchy membership function, and their variations with the crack growth are evaluated. Finally, the DIs in all excitation-receive paths are fused by the damage presence probability imaging method to approximately characterize the variations of crack lengths, proving that the algorithm proposed in this paper is feasible and effective.
