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RSS2024 Vol. 43, No. 6
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2024, 43(6): 917-924.
doi: 10.13433/j.cnki.1003-8728.20230031
PDF 1915KB
Abstract:
Traditional sparse representation (SR) methods have been widely studied in fault diagnosis field due to their unique advantages in impact feature extraction.However, the traditional SR theory is based on an assumption of Gaussian distribution of interference noise, which makes it difficult to apply to the actual scenario where multiple noise distributions are involved. Regarding the issue above, a new sparse representation method of impact features under mixed Gaussian noise conditionis proposed in this study. Depending on the Bayesian framework of the traditional sparse representation theory and the universal approximation property of the mixed Gaussian distribution, a sparse decomposition model of the mixed Gaussian noiseis established based on the db4 wavelet dictionary, and an optimization algorithm based on Expectation-Maximum (EM) and Alternating Direction Method of Multipliers (ADMM) is derived for model solution. The simulation and experimental results show that the proposed method can effectively extract the weak impact feature under mixed noise interference.
Traditional sparse representation (SR) methods have been widely studied in fault diagnosis field due to their unique advantages in impact feature extraction.However, the traditional SR theory is based on an assumption of Gaussian distribution of interference noise, which makes it difficult to apply to the actual scenario where multiple noise distributions are involved. Regarding the issue above, a new sparse representation method of impact features under mixed Gaussian noise conditionis proposed in this study. Depending on the Bayesian framework of the traditional sparse representation theory and the universal approximation property of the mixed Gaussian distribution, a sparse decomposition model of the mixed Gaussian noiseis established based on the db4 wavelet dictionary, and an optimization algorithm based on Expectation-Maximum (EM) and Alternating Direction Method of Multipliers (ADMM) is derived for model solution. The simulation and experimental results show that the proposed method can effectively extract the weak impact feature under mixed noise interference.
2024, 43(6): 925-933.
doi: 10.13433/j.cnki.1003-8728.20230020
Abstract:
As an important part of the propulsion device, the gear transmission system can still maintain good dynamic characteristics in the mode switching process, which has an important influence on the safety and maneuverability of the ship structure. In this paper, the combined drive helical gear transmission system of a ship is taken as the research object, the pure torsional dynamic model of the system is established, and the MASTA software is used to verify the correctness of the model. Based on the model, the dynamic characteristics of mode switching process between single drive mode and combined drive mode were analyzed. And the model is used to find the optimal speed and input torque of the mode switching, and the influence of the meshing stiffness and the torsional stiffness of the shaft on the mode switching process is explored. The results show that the optimum speed of gear 1 is 2250 r/min, and the optimum input torque of gear 7 is 3100 Nm. When the meshing stiffness increases 1 ~ 1.2 times, the vibration of each gear pair can be reduced at different switching stages. As long as the torsional stiffness of the shaft is more than 0.8 times of the base torsional stiffness, the vibration degree of each gear pair in the system will not change significantly.
As an important part of the propulsion device, the gear transmission system can still maintain good dynamic characteristics in the mode switching process, which has an important influence on the safety and maneuverability of the ship structure. In this paper, the combined drive helical gear transmission system of a ship is taken as the research object, the pure torsional dynamic model of the system is established, and the MASTA software is used to verify the correctness of the model. Based on the model, the dynamic characteristics of mode switching process between single drive mode and combined drive mode were analyzed. And the model is used to find the optimal speed and input torque of the mode switching, and the influence of the meshing stiffness and the torsional stiffness of the shaft on the mode switching process is explored. The results show that the optimum speed of gear 1 is 2250 r/min, and the optimum input torque of gear 7 is 3100 Nm. When the meshing stiffness increases 1 ~ 1.2 times, the vibration of each gear pair can be reduced at different switching stages. As long as the torsional stiffness of the shaft is more than 0.8 times of the base torsional stiffness, the vibration degree of each gear pair in the system will not change significantly.
2024, 43(6): 934-942.
doi: 10.13433/j.cnki.1003-8728.20220296
Abstract:
In order to realize the intelligent motion control of multi-DOF (degree of freedom) boom of construction machinery, combined with the parametric joint method and MOEA/D (Multi-objective evolutionary algorithm based on decomposition), an IM-IK algorithm (Improved MOEA/D-inverse kinematics) is proposed to solve the inverse kinematics problem of redundant manipulator in this paper. The algorithm adds an adaptive interval search strategy to the MOEA/D algorithm framework to improve the local search ability and solution speed of the algorithm. IM-IK algorithm is applied to an 8-DOF redundant manipulator, and compared with NSGA-II (Nondominated sorting genetic algorithm II), MOEA/D and T-IK algorithms. All test indexes prove that IM-IK algorithm has better comprehensive performance than other algorithms in dealing with the inverse kinematics of redundant manipulator, and can meet the position and orientation accuracy requirements of manipulator's end effector, it can also ensure the joints motion continuity of the manipulator and effectively avoids the joints limit.
In order to realize the intelligent motion control of multi-DOF (degree of freedom) boom of construction machinery, combined with the parametric joint method and MOEA/D (Multi-objective evolutionary algorithm based on decomposition), an IM-IK algorithm (Improved MOEA/D-inverse kinematics) is proposed to solve the inverse kinematics problem of redundant manipulator in this paper. The algorithm adds an adaptive interval search strategy to the MOEA/D algorithm framework to improve the local search ability and solution speed of the algorithm. IM-IK algorithm is applied to an 8-DOF redundant manipulator, and compared with NSGA-II (Nondominated sorting genetic algorithm II), MOEA/D and T-IK algorithms. All test indexes prove that IM-IK algorithm has better comprehensive performance than other algorithms in dealing with the inverse kinematics of redundant manipulator, and can meet the position and orientation accuracy requirements of manipulator's end effector, it can also ensure the joints motion continuity of the manipulator and effectively avoids the joints limit.
2024, 43(6): 943-949.
doi: 10.13433/j.cnki.1003-8728.20230003
Abstract:
Because the fault features of a planetary cycloid pinwheel reducer are difficult to extract in the swing fatigue experiment, this paper proposes a method that combines empirical mode decomposition and order tracking analysis to conduct the fault diagnosis of the reducer. Through performing equiangular domain resampling, empirical mode decomposition, calculating the kurtosis value of the intrinsic mode function, selecting the intrinsic mode component for reconstruction and the fast Fourier transform of collected time domain signals, the order map is verified. The results show that the method can accurately extract the inherent modal components that contain the information on faults and identify the fault features of the planetary cycloid pinwheel reducer in the non-stationary state.
Because the fault features of a planetary cycloid pinwheel reducer are difficult to extract in the swing fatigue experiment, this paper proposes a method that combines empirical mode decomposition and order tracking analysis to conduct the fault diagnosis of the reducer. Through performing equiangular domain resampling, empirical mode decomposition, calculating the kurtosis value of the intrinsic mode function, selecting the intrinsic mode component for reconstruction and the fast Fourier transform of collected time domain signals, the order map is verified. The results show that the method can accurately extract the inherent modal components that contain the information on faults and identify the fault features of the planetary cycloid pinwheel reducer in the non-stationary state.
2024, 43(6): 950-956.
doi: 10.13433/j.cnki.1003-8728.20220295
Abstract:
Based on the nonlinear fatigue cumulative damage evolution model and continuous damage theory, considering the threshold strain of damage's genration, a damage model is established, in which the fatigue cumulative damage is affected by the current strain state and loading times. The parameters of fatigue cumulative damage evolution model are determined by using the experimental data, and the rationality of the model is verified. The damage evolution simulation of fatigue accumulation related to loading times and deformation is realized via ABAQUS software, and the fatigue simulation calculation of three-point bending simply supported beams is carried out. Considering the linear distribution of damage along the thickness direction of the damaged layer, the bending stiffness of beams with unilateral damage and bilateral damage are studied respectively.
Based on the nonlinear fatigue cumulative damage evolution model and continuous damage theory, considering the threshold strain of damage's genration, a damage model is established, in which the fatigue cumulative damage is affected by the current strain state and loading times. The parameters of fatigue cumulative damage evolution model are determined by using the experimental data, and the rationality of the model is verified. The damage evolution simulation of fatigue accumulation related to loading times and deformation is realized via ABAQUS software, and the fatigue simulation calculation of three-point bending simply supported beams is carried out. Considering the linear distribution of damage along the thickness direction of the damaged layer, the bending stiffness of beams with unilateral damage and bilateral damage are studied respectively.
2024, 43(6): 957-961.
doi: 10.13433/j.cnki.1003-8728.20220301
Abstract:
In order to simplify the structure of the traditional automobile braking system and better meet the needs of intelligent networked vehicles for rapid adjustment of braking force, a pump-controlled direct-drive BBW unit is proposed, which adopts pump-controlled direct-drive volumetric servo technology, its motor directly drives the two-way gear pump to realize the control and rapid adjustment of the brake wheel cylinder pressure, eliminates the throttling loss of the valve control system, and effectively improves the system efficiency. Based on the parameter design and mathematical modeling of the pump-controlled direct-drive BBW unit, a prototype of the brake unit and a performance test platform are trial-produced, and the response curve and following characteristics of the wheel cylinder pressure change are analyzed. The simulation and test results prove the feasibility of the pump-controlled direct-drive BBW unit;the 12 MPa pressure step response time is 200 ms and the system has good response speed and stability,it provides a new implementation scheme for the BBW technology.
In order to simplify the structure of the traditional automobile braking system and better meet the needs of intelligent networked vehicles for rapid adjustment of braking force, a pump-controlled direct-drive BBW unit is proposed, which adopts pump-controlled direct-drive volumetric servo technology, its motor directly drives the two-way gear pump to realize the control and rapid adjustment of the brake wheel cylinder pressure, eliminates the throttling loss of the valve control system, and effectively improves the system efficiency. Based on the parameter design and mathematical modeling of the pump-controlled direct-drive BBW unit, a prototype of the brake unit and a performance test platform are trial-produced, and the response curve and following characteristics of the wheel cylinder pressure change are analyzed. The simulation and test results prove the feasibility of the pump-controlled direct-drive BBW unit;the 12 MPa pressure step response time is 200 ms and the system has good response speed and stability,it provides a new implementation scheme for the BBW technology.
2024, 43(6): 962-966.
doi: 10.13433/j.cnki.1003-8728.20220312
Abstract:
Because of the bad operating environment of the fan, when the bearing is faulty, its vibration signal is often disturbed by environmental noise, which leads to the difficulty of fault information extraction for vibration signal. To solve this problem, this paper proposes a feature extraction method based on complementary ensemble empirical mode decomposition (CEEMD) and sample entropy (SE), which combines the Tianying optimization algorithm (AO) and support vector machine (SVM) for fault classification, and realizes the fault diagnosis of fan bearings. In this paper, the bearing data of Case Western Reserve University are used for the experiment, and the real fan bearing data are used for further verification. The experimental results show that the proposed method has high fault identification accuracy when fault vibration signal is disturbed by environmental noise.
Because of the bad operating environment of the fan, when the bearing is faulty, its vibration signal is often disturbed by environmental noise, which leads to the difficulty of fault information extraction for vibration signal. To solve this problem, this paper proposes a feature extraction method based on complementary ensemble empirical mode decomposition (CEEMD) and sample entropy (SE), which combines the Tianying optimization algorithm (AO) and support vector machine (SVM) for fault classification, and realizes the fault diagnosis of fan bearings. In this paper, the bearing data of Case Western Reserve University are used for the experiment, and the real fan bearing data are used for further verification. The experimental results show that the proposed method has high fault identification accuracy when fault vibration signal is disturbed by environmental noise.
2024, 43(6): 967-974.
doi: 10.13433/j.cnki.1003-8728.20230065
Abstract:
Aiming at the problemthat the intrinsic time scale decomposition (ITD) method is difficult to extract bearing fault features under the influence of strong background noise, a new fault features extraction method for rolling bearings combining ITD and parameter optimized multipoint optimal minimum entropy deconvolution adjusted (MOMEDA) is proposed. First, the ITD component containing rich fault information is extractedfrom fault signals according to the principle of maximum crest factor of envelope spectrum. Then, the MOMEDA noise reduction process is performed on the decomposedcomponent. The two parameters - fault period T and filter length L that affect the filtering effect of MOMEDA, are optimized with multi-point kurtosis and Gini index of square envelope spectrum respectively. Finally, envelope spectrum analysis is performed to extract fault characteristic frequencies. The analysis of the simulated signal and the measured signal shows that the new method can effectively extract the fault features of rolling bearings under the strong noise interference.
Aiming at the problemthat the intrinsic time scale decomposition (ITD) method is difficult to extract bearing fault features under the influence of strong background noise, a new fault features extraction method for rolling bearings combining ITD and parameter optimized multipoint optimal minimum entropy deconvolution adjusted (MOMEDA) is proposed. First, the ITD component containing rich fault information is extractedfrom fault signals according to the principle of maximum crest factor of envelope spectrum. Then, the MOMEDA noise reduction process is performed on the decomposedcomponent. The two parameters - fault period T and filter length L that affect the filtering effect of MOMEDA, are optimized with multi-point kurtosis and Gini index of square envelope spectrum respectively. Finally, envelope spectrum analysis is performed to extract fault characteristic frequencies. The analysis of the simulated signal and the measured signal shows that the new method can effectively extract the fault features of rolling bearings under the strong noise interference.
2024, 43(6): 975-983.
doi: 10.13433/j.cnki.1003-8728.20230024
Abstract:
The erosion damage is a frequent failure for the elbow in gas-solid two-phase system, which is directly related to the reliability and working life of the pipeline system. A petal shaped elbow structure to improve the anti-erosion performance of the elbow is proposed. The gas-solid flow characteristics of the elbow structure were analyzed by using CFD-DPM method. The results show that the petal-shaped structure at different positions has the same V-shaped erosion distribution as the conventional elbow. Before the first impact on the particle wall, the particle track can be changed and a circulation zone can be formed on the back of the particle, which can inhibit the erosion to a certain extent. The best anti-erosion position of petal-shaped structure is θ = 20° and this position does not change with the change of flow rate and particle mass flow rate. Comparing with the conventional elbow without petal-shaped structure, the anti-erosion performance is improved by 17.27%. This structure can improve the erosion resistance of the elbow and extend the life of the pipe.
The erosion damage is a frequent failure for the elbow in gas-solid two-phase system, which is directly related to the reliability and working life of the pipeline system. A petal shaped elbow structure to improve the anti-erosion performance of the elbow is proposed. The gas-solid flow characteristics of the elbow structure were analyzed by using CFD-DPM method. The results show that the petal-shaped structure at different positions has the same V-shaped erosion distribution as the conventional elbow. Before the first impact on the particle wall, the particle track can be changed and a circulation zone can be formed on the back of the particle, which can inhibit the erosion to a certain extent. The best anti-erosion position of petal-shaped structure is θ = 20° and this position does not change with the change of flow rate and particle mass flow rate. Comparing with the conventional elbow without petal-shaped structure, the anti-erosion performance is improved by 17.27%. This structure can improve the erosion resistance of the elbow and extend the life of the pipe.
2024, 43(6): 984-990.
doi: 10.13433/j.cnki.1003-8728.20220309
Abstract:
With the increasing aging degree in China, for meeting more and more elderly people needs,a ride-by-ride walking aid device for lower limbs is designed and kinematics simulation is carried out. Firstly, the degree of freedom of the walking aid is allocated by analyzing the characteristics of human lower limb movement, and the weight reduction model of the walking aid is established and its feasibility is verified. Secondly, the entity modeling of the walking aid device is established. Then the standard D-H method is used to analyze the kinematics of the swing phase of the walker. Finally, the human lower limb angular displacement drive function is written based on OpenSim open source software, and the kinematics simulation is carried out with virtual prototyping technology to obtain the angular displacement curve of the walker joint. The simulation results show that the riding lower limb walker has good physical coupling with the human body.
With the increasing aging degree in China, for meeting more and more elderly people needs,a ride-by-ride walking aid device for lower limbs is designed and kinematics simulation is carried out. Firstly, the degree of freedom of the walking aid is allocated by analyzing the characteristics of human lower limb movement, and the weight reduction model of the walking aid is established and its feasibility is verified. Secondly, the entity modeling of the walking aid device is established. Then the standard D-H method is used to analyze the kinematics of the swing phase of the walker. Finally, the human lower limb angular displacement drive function is written based on OpenSim open source software, and the kinematics simulation is carried out with virtual prototyping technology to obtain the angular displacement curve of the walker joint. The simulation results show that the riding lower limb walker has good physical coupling with the human body.
2024, 43(6): 991-999.
doi: 10.13433/j.cnki.1003-8728.20220300
Abstract:
Aiming at high-altitude operations in the gas and pipeline engineering fields, a permanent magnet-assisted dual-gripper bionic climbing robot is designed. The robot has two gaits, creeping and flipping, and the step distance of the creeping gait can be adjusted. In order to prevent the robot from slipping and overturning instability, mechanical analysis was carried out. Kinematics and climbing gait analysis were performed on the robot according to its configuration. The linear path planning of the creeping climbing gait is carried out, and the two gaits are simulated in the SOLIDWORKS MOTION environment. The prototype test shows that the robot has the good stability in both creeping and turning gaits, and the two gaits can be used to achieve obstacles overturning. The robot has the good application of high-altitude operation in the pipeline engineering.
Aiming at high-altitude operations in the gas and pipeline engineering fields, a permanent magnet-assisted dual-gripper bionic climbing robot is designed. The robot has two gaits, creeping and flipping, and the step distance of the creeping gait can be adjusted. In order to prevent the robot from slipping and overturning instability, mechanical analysis was carried out. Kinematics and climbing gait analysis were performed on the robot according to its configuration. The linear path planning of the creeping climbing gait is carried out, and the two gaits are simulated in the SOLIDWORKS MOTION environment. The prototype test shows that the robot has the good stability in both creeping and turning gaits, and the two gaits can be used to achieve obstacles overturning. The robot has the good application of high-altitude operation in the pipeline engineering.
2024, 43(6): 1000-1005.
doi: 10.13433/j.cnki.1003-8728.20230005
Abstract:
An experimental study of the interaction between combustion phase, combustion duration and average indicated thermal efficiency of a single-cylinder gasoline engine before and after combustion chamber wall polishing was carried out. The results show that when the single-cylinder gasoline engine operates at stoichiometric air-fuel ratio, low load and low pressure ratios, the heat transfer loss of the polished combustion chamber wall is reduced and the economic performance is improved, and the average indicated thermal efficiency increases from 40.8% to 42.2%. With the increase of load and compression ratios, the knock effect caused by the reduction of heat transfer loss of the polished combustion chamber wall is enhanced, the combustion phase is delayed and the combustion duration is prolonged, and finally the average indicated thermal efficiency decreases. When the gasoline engine operates in the lean combustion mode, the average indicated thermal efficiency increases greatly, and the maximum thermal efficiency exceeds 45%. When the gasoline engine enters into the knock area and operates at a load of 10.5 bar, the heat transfer loss after wall polishing is reduced and the knock effect is enhanced, resulting in the overall decrease of the average indicated thermal efficiency compared with that before wall polishing.
An experimental study of the interaction between combustion phase, combustion duration and average indicated thermal efficiency of a single-cylinder gasoline engine before and after combustion chamber wall polishing was carried out. The results show that when the single-cylinder gasoline engine operates at stoichiometric air-fuel ratio, low load and low pressure ratios, the heat transfer loss of the polished combustion chamber wall is reduced and the economic performance is improved, and the average indicated thermal efficiency increases from 40.8% to 42.2%. With the increase of load and compression ratios, the knock effect caused by the reduction of heat transfer loss of the polished combustion chamber wall is enhanced, the combustion phase is delayed and the combustion duration is prolonged, and finally the average indicated thermal efficiency decreases. When the gasoline engine operates in the lean combustion mode, the average indicated thermal efficiency increases greatly, and the maximum thermal efficiency exceeds 45%. When the gasoline engine enters into the knock area and operates at a load of 10.5 bar, the heat transfer loss after wall polishing is reduced and the knock effect is enhanced, resulting in the overall decrease of the average indicated thermal efficiency compared with that before wall polishing.
2024, 43(6): 1006-1015.
doi: 10.13433/j.cnki.1003-8728.20230033
Abstract:
For the hydraulic grading hydrocyclone in the sludge water treatment of coal preparation plant, there is a problem of low separation performance of equipment due to unreasonable matching of variable parameters. In this paper, taking the YD350-14 hydraulic graded hydrocyclone commonly used in coal preparation plants as the research object, and the separation efficiency and pressure drop as the evaluation index of the separation performance of the hydrocyclone, the matching relationship between the variable parameters of the hydrocyclone (feed concentration, feed flow and installation angle) was studied and optimized based on the response surface method and the non-dominated sorting genetic algorithm (NSGA-II). Finally, according to the Pareto front, the best working parameters of the hydrocyclone are determined as follows: when the hydrocyclone feed concentration is 12 g/L, the installation angle is 80°, and the infeed flow is 80 m3/h, the separation efficiency can be achieved by 86.07%, and the pressure drop is 1155.62 Pa. The field verification of the separation efficiency matching model shows that the separation efficiency is increased by 5.07% after matching optimization, which verifies that the matching model can effectively improve the separation efficiency of the hydrocyclone. This research provides a theoretical basis for the reasonable matching of the process parameters of the hydrocyclone in the coal preparation plants, and opens up a new direction for improving the separation efficiency of the hydraulic gradinghydrocyclone.
For the hydraulic grading hydrocyclone in the sludge water treatment of coal preparation plant, there is a problem of low separation performance of equipment due to unreasonable matching of variable parameters. In this paper, taking the YD350-14 hydraulic graded hydrocyclone commonly used in coal preparation plants as the research object, and the separation efficiency and pressure drop as the evaluation index of the separation performance of the hydrocyclone, the matching relationship between the variable parameters of the hydrocyclone (feed concentration, feed flow and installation angle) was studied and optimized based on the response surface method and the non-dominated sorting genetic algorithm (NSGA-II). Finally, according to the Pareto front, the best working parameters of the hydrocyclone are determined as follows: when the hydrocyclone feed concentration is 12 g/L, the installation angle is 80°, and the infeed flow is 80 m3/h, the separation efficiency can be achieved by 86.07%, and the pressure drop is 1155.62 Pa. The field verification of the separation efficiency matching model shows that the separation efficiency is increased by 5.07% after matching optimization, which verifies that the matching model can effectively improve the separation efficiency of the hydrocyclone. This research provides a theoretical basis for the reasonable matching of the process parameters of the hydrocyclone in the coal preparation plants, and opens up a new direction for improving the separation efficiency of the hydraulic gradinghydrocyclone.
2024, 43(6): 1016-1023.
doi: 10.13433/j.cnki.1003-8728.20220308
Abstract:
The vibration characteristic of the pump is an important factor affecting the stable and safe operation, and also an important index to measure the performance of the pump. The CFD model of multi-stage centrifugal pump is built, simulation calculation obtains the fluid excitation force were for the equivalent dynamic characteristic solution. Simultaneously, the Ansys Workbench rotor vibration model is established to analyze the influence of the clocking effect on the rotor modal response. The research shows that the laws of fluid exciting force is identical on the impellers, and the largest exciting force at the first-stage impeller; The stiffness and damping coefficients of the impeller tend to increase, and the impeller of the last stage is about 2 times larger than first stage; The clocking effect can significantly reduce the radial force on the rotor system, and the peak amplitude is reduced by about 35% and 41% at first rotor frequency of 7APF (414 Hz) and the secondary rotor frequency of 8APF (473 Hz).
The vibration characteristic of the pump is an important factor affecting the stable and safe operation, and also an important index to measure the performance of the pump. The CFD model of multi-stage centrifugal pump is built, simulation calculation obtains the fluid excitation force were for the equivalent dynamic characteristic solution. Simultaneously, the Ansys Workbench rotor vibration model is established to analyze the influence of the clocking effect on the rotor modal response. The research shows that the laws of fluid exciting force is identical on the impellers, and the largest exciting force at the first-stage impeller; The stiffness and damping coefficients of the impeller tend to increase, and the impeller of the last stage is about 2 times larger than first stage; The clocking effect can significantly reduce the radial force on the rotor system, and the peak amplitude is reduced by about 35% and 41% at first rotor frequency of 7APF (414 Hz) and the secondary rotor frequency of 8APF (473 Hz).
2024, 43(6): 1024-1030.
doi: 10.13433/j.cnki.1003-8728.20220297
Abstract:
Taking the helical gear in the twelfth transmission of a heavy truck as the object, the effect of the roll finishing on the surface roughness, surface topography, microhardness, and residual stress of gearwereinvestigated,and the transmission efficiency and noise of the unpolished and polished transmission were obtained and compared. Results show that the tooth surface roughness Raof gear decreases from 0.815 to 0.317 μm, the surface crater marks treated by shot peening disappear, and the surface topography is uniform. The surface microhardness and residual stress of the tooth surface are improved significantly, and the surface residual compressive stress exceeds 1 000 MPa. The residual compressive stresswith a depth greater than 0.02 mm cannot be enlarged by roll finishing. After roll finishing, the comprehensive transmission efficiency is increased by 0.54% approximately, and the average noise value is reduced by about 1-3 dB(A).
Taking the helical gear in the twelfth transmission of a heavy truck as the object, the effect of the roll finishing on the surface roughness, surface topography, microhardness, and residual stress of gearwereinvestigated,and the transmission efficiency and noise of the unpolished and polished transmission were obtained and compared. Results show that the tooth surface roughness Raof gear decreases from 0.815 to 0.317 μm, the surface crater marks treated by shot peening disappear, and the surface topography is uniform. The surface microhardness and residual stress of the tooth surface are improved significantly, and the surface residual compressive stress exceeds 1 000 MPa. The residual compressive stresswith a depth greater than 0.02 mm cannot be enlarged by roll finishing. After roll finishing, the comprehensive transmission efficiency is increased by 0.54% approximately, and the average noise value is reduced by about 1-3 dB(A).
2024, 43(6): 1031-1041.
doi: 10.13433/j.cnki.1003-8728.20230006
Abstract:
Aiming at the problems that the layout of the sensor device in the existing wireless monitoring system for tool vibration has a large effect on the transformation of the tool holder and the high cost, a kind of wireless detection system of tool vibration used in milling based on the low power consumption and miniaturization of the sensor device is designed by adopting the low-power Bluetooth 5.0, MEMS sensor and Python. Sensing device testing and milling Comparing with the existing similar sensing devices, the system sensing device ensured signal transmission performance, reduced power consumption, and achieved miniaturization; the denoising effect of the present variational model decomposition-dual tree complex wavelet denoising method based on the fusion index is better than other common denoising methods such as wavelet threshold; comparing with the existing wireless system, the designed wireless system used the same convolutional neural networks model to recognize the tool wear status with higher accuracy. The results showed that the designed wireless system was more practical and can effectively retain the characteristics of the vibration signal, provideing a reliable way to obtain vibration data for tool wear status recognition.
Aiming at the problems that the layout of the sensor device in the existing wireless monitoring system for tool vibration has a large effect on the transformation of the tool holder and the high cost, a kind of wireless detection system of tool vibration used in milling based on the low power consumption and miniaturization of the sensor device is designed by adopting the low-power Bluetooth 5.0, MEMS sensor and Python. Sensing device testing and milling Comparing with the existing similar sensing devices, the system sensing device ensured signal transmission performance, reduced power consumption, and achieved miniaturization; the denoising effect of the present variational model decomposition-dual tree complex wavelet denoising method based on the fusion index is better than other common denoising methods such as wavelet threshold; comparing with the existing wireless system, the designed wireless system used the same convolutional neural networks model to recognize the tool wear status with higher accuracy. The results showed that the designed wireless system was more practical and can effectively retain the characteristics of the vibration signal, provideing a reliable way to obtain vibration data for tool wear status recognition.
2024, 43(6): 1042-1047.
doi: 10.13433/j.cnki.1003-8728.20230010
Abstract:
In order to solve the problem that the original DenseNet model with a long time and low accuracy to detect workpiece surface roughness, a deep learning model for workpiece surface roughness detection is proposed by combining the attention mechanism of convolutional layer filter and the scale coefficient of batch normalized layer. Firstly, the importance value of attention mechanism of convolution layer filter is used to determine the redundant channels in Dense Block module. Secondly, the scale coefficient of batch normalization layer was introduced into the Dense Block module of DenseNet model in order to distinguish the importance of feature channels. Finally, the attention importance value of convolution layer filter and scale coefficient of batch normalization layer are combined to crop redundant channels. Experimental results show that the accuracy of original DenseNet model is 91.875%, and the detection time is 483 s. When pruning rate is 20%, the detection accuracy was 96.875%, and detection time was 255 s. Comparing with the conventional model, the improved DenseNet model has better detection effect and larger application in the field of quality inspection.
In order to solve the problem that the original DenseNet model with a long time and low accuracy to detect workpiece surface roughness, a deep learning model for workpiece surface roughness detection is proposed by combining the attention mechanism of convolutional layer filter and the scale coefficient of batch normalized layer. Firstly, the importance value of attention mechanism of convolution layer filter is used to determine the redundant channels in Dense Block module. Secondly, the scale coefficient of batch normalization layer was introduced into the Dense Block module of DenseNet model in order to distinguish the importance of feature channels. Finally, the attention importance value of convolution layer filter and scale coefficient of batch normalization layer are combined to crop redundant channels. Experimental results show that the accuracy of original DenseNet model is 91.875%, and the detection time is 483 s. When pruning rate is 20%, the detection accuracy was 96.875%, and detection time was 255 s. Comparing with the conventional model, the improved DenseNet model has better detection effect and larger application in the field of quality inspection.
2024, 43(6): 1048-1055.
doi: 10.13433/j.cnki.1003-8728.20240080
Abstract:
The dual-pole magnetic abrasive finishing method (DMAF) is proposed for the surface planarization of single crystal silicon, and a set of dual-pole magnetic abrasive finishing device is designed.The processing mechanism of DMAF is explored, the effects of the key machining parameters on the surface quality of single crystal silicon is clarified and the machining parameters through single-factor comparative experimentsis optimized.By using ANSYS MAXWELL finite element software to simulate the magnetic field intensities in both traditional planar magnetic abrasive finishing method and DMAF, the magnetic induction intensity in the finishing area produced in two different finishing methods were compared to obtain the quantitative analysis of the finishing pressure of magnetic abrasive particles. According to the results of single-factor experiments, the optimizedpolishing parameters obtained in DMAF of the surface polishing of single crystal silicon wafers were in the following: the abrasive combination of #200Fe3O4+#8000WA, the gap of magnetic poles at 12 mm, magnetic pole speed at 300 r/min, and abrasive mass ratio at 3:1. It was indicated in the experimental results that with the optimal machining parameters, the single crystal silicon wafers reached their average surface roughness as low as 8 nm from the initial 0.578 μm after 60 min finishing, and the workpiecein the polishing area almost achieveda mirror finishing effect. The simulation results show that comparing with the traditional plane magnetic abrasive finishing method, the DMAF can significantly improve the magnetic field intensity of the processing area, and the intensity produced in DMAF is about 1.5 times that in the traditional magnetic finishing method.
The dual-pole magnetic abrasive finishing method (DMAF) is proposed for the surface planarization of single crystal silicon, and a set of dual-pole magnetic abrasive finishing device is designed.The processing mechanism of DMAF is explored, the effects of the key machining parameters on the surface quality of single crystal silicon is clarified and the machining parameters through single-factor comparative experimentsis optimized.By using ANSYS MAXWELL finite element software to simulate the magnetic field intensities in both traditional planar magnetic abrasive finishing method and DMAF, the magnetic induction intensity in the finishing area produced in two different finishing methods were compared to obtain the quantitative analysis of the finishing pressure of magnetic abrasive particles. According to the results of single-factor experiments, the optimizedpolishing parameters obtained in DMAF of the surface polishing of single crystal silicon wafers were in the following: the abrasive combination of #200Fe3O4+#8000WA, the gap of magnetic poles at 12 mm, magnetic pole speed at 300 r/min, and abrasive mass ratio at 3:1. It was indicated in the experimental results that with the optimal machining parameters, the single crystal silicon wafers reached their average surface roughness as low as 8 nm from the initial 0.578 μm after 60 min finishing, and the workpiecein the polishing area almost achieveda mirror finishing effect. The simulation results show that comparing with the traditional plane magnetic abrasive finishing method, the DMAF can significantly improve the magnetic field intensity of the processing area, and the intensity produced in DMAF is about 1.5 times that in the traditional magnetic finishing method.
2024, 43(6): 1056-1062.
doi: 10.13433/j.cnki.1003-8728.20230022
Abstract:
From the perspectives of data collection and transmission reliability, anti-interference ability, electromagnetic compatibility, and user-friendly interface, a high-voltage circuit breaker（HVCB）multi signal (including sound, vibration, and travel signals) joint monitoring experimental platform has been built. The platform includes three parts: sound, vibration, travel sensor design and selection, acquisition system control box design, and upper computer design. Then, taking the opening spring fault of SF6 HVCB as an example, the fault was simulated and set up. Through the experimental platform built, the collection, transmission, storage, presentation, and waveform comparison analysis of fault signals were achieved. The application of the HVCB multi signal joint monitoring experimental platform was achieved, providing a reliable data foundation for subsequent mechanical fault feature extraction and fault diagnosis of HVCBs.
From the perspectives of data collection and transmission reliability, anti-interference ability, electromagnetic compatibility, and user-friendly interface, a high-voltage circuit breaker（HVCB）multi signal (including sound, vibration, and travel signals) joint monitoring experimental platform has been built. The platform includes three parts: sound, vibration, travel sensor design and selection, acquisition system control box design, and upper computer design. Then, taking the opening spring fault of SF6 HVCB as an example, the fault was simulated and set up. Through the experimental platform built, the collection, transmission, storage, presentation, and waveform comparison analysis of fault signals were achieved. The application of the HVCB multi signal joint monitoring experimental platform was achieved, providing a reliable data foundation for subsequent mechanical fault feature extraction and fault diagnosis of HVCBs.
2024, 43(6): 1063-1071.
doi: 10.13433/j.cnki.1003-8728.20220310
Abstract:
To solve the problem that the parking path generated by the existing bidirectional rapidly-exploring random tree (Bi-RRT*) algorithmdoes not meet a vehicle’s kinematics constraints, path twists and turns and slow convergence speed, an improved Bi-RRT* algorithm is proposed. First, based on the vehicle collision detection model, obstacles are magnified to ensure the safe parking distance for the vehicle. Secondly, the Reeds-Shepp curve is used to expand the nodes, so that the path connection meets the vehicle’s kinematics constraints. Furthermore, in order to improve the search efficiency and sampling success rate of the Bi-RRT*algorithm, obstacle avoidance and radial constrained sampling strategies are introduced. Finally, the path nodes are uniformly interpolated, and the RRT* tree based on the starting point is used to remove redundant paths to realize the smooth optimization of the path. The simulation results show that compared with the existing Bi-RRT* algorithm, the path planned by the improved Bi-RRT* algorithm not only meets the obstacle avoidance requirements and kinematic constraints but is also superior in planning time and path quality.
To solve the problem that the parking path generated by the existing bidirectional rapidly-exploring random tree (Bi-RRT*) algorithmdoes not meet a vehicle’s kinematics constraints, path twists and turns and slow convergence speed, an improved Bi-RRT* algorithm is proposed. First, based on the vehicle collision detection model, obstacles are magnified to ensure the safe parking distance for the vehicle. Secondly, the Reeds-Shepp curve is used to expand the nodes, so that the path connection meets the vehicle’s kinematics constraints. Furthermore, in order to improve the search efficiency and sampling success rate of the Bi-RRT*algorithm, obstacle avoidance and radial constrained sampling strategies are introduced. Finally, the path nodes are uniformly interpolated, and the RRT* tree based on the starting point is used to remove redundant paths to realize the smooth optimization of the path. The simulation results show that compared with the existing Bi-RRT* algorithm, the path planned by the improved Bi-RRT* algorithm not only meets the obstacle avoidance requirements and kinematic constraints but is also superior in planning time and path quality.
2024, 43(6): 1072-1077.
doi: 10.13433/j.cnki.1003-8728.20230018
Abstract:
Aiming at the reasonable bottleneck of accelerated data extrapolation, based on high temperature accelerated test data, a weighted extrapolation method is proposed to achieve accurate prediction of rubber life. Firstly, the nonlinear accelerated degradation model for rubber properties is established, and the nonlinear least squares method is used to realize the identification of acceleration factors at different temperatures. Secondly, the weighted calculation of the activation energy is conducted. Finally, the life at the service temperature is calculated from the activation energy, and the validity of the method is verified by modeling the existing data. The research can provide support for improving the accuracy of accelerated life prediction of rubber parts, and can also provide reference for evaluating the reliability of other mechanical parts.
Aiming at the reasonable bottleneck of accelerated data extrapolation, based on high temperature accelerated test data, a weighted extrapolation method is proposed to achieve accurate prediction of rubber life. Firstly, the nonlinear accelerated degradation model for rubber properties is established, and the nonlinear least squares method is used to realize the identification of acceleration factors at different temperatures. Secondly, the weighted calculation of the activation energy is conducted. Finally, the life at the service temperature is calculated from the activation energy, and the validity of the method is verified by modeling the existing data. The research can provide support for improving the accuracy of accelerated life prediction of rubber parts, and can also provide reference for evaluating the reliability of other mechanical parts.
2024, 43(6): 1078-1083.
doi: 10.13433/j.cnki.1003-8728.20220307
Abstract:
In order to study the application of optimized BCC lattice structure in single pile foundation collision of offshore wind turbine, an anti-collision device model is designed. Firstly, based on the Workbench analysis platform, the unit cell size of the BCC lattice structure is optimized by multi-objective method, and the simulation results before and after optimization are compared to verify the reliability of the optimized size. Subsequently, the equivalent model of BCC lattice structure is established by using the asymptotic homogenization theory, and the simulation performance of the anti-collision device model of single pile foundation of offshore wind turbine in collision is compared and analyzed. The research shows that the anti-collision device not only has buffering property, but also can effectively reduce the damage degree of single pile foundation after collision.
In order to study the application of optimized BCC lattice structure in single pile foundation collision of offshore wind turbine, an anti-collision device model is designed. Firstly, based on the Workbench analysis platform, the unit cell size of the BCC lattice structure is optimized by multi-objective method, and the simulation results before and after optimization are compared to verify the reliability of the optimized size. Subsequently, the equivalent model of BCC lattice structure is established by using the asymptotic homogenization theory, and the simulation performance of the anti-collision device model of single pile foundation of offshore wind turbine in collision is compared and analyzed. The research shows that the anti-collision device not only has buffering property, but also can effectively reduce the damage degree of single pile foundation after collision.
2024, 43(6): 1084-1091.
doi: 10.13433/j.cnki.1003-8728.20230001
Abstract:
In view of the current situation that the influence of N element on the pitting corrosion resistance of austenitic stainless steel and its mechanism are not clear, the mechanical properties and electrochemical impedance spectroscopy of nitrogen controlled stainless steel 316LN are tested. The results showed that the mechanical properties and corrosion resistance of 316LN at room temperature were superior to those of 316L stainless steel, but the corrosion resistance of 316LN stainless steel was degraded significantly with the increasing of temperature and medium concentration. At room temperature and low concentration of chloride ion, the impedance of the passivation film on 316LN stainless steel is higher than that of 316L stainless steel, which indicated that the stability of the passivation film on 316LN stainless steel is higher than that of 316L stainless steel under the synergistic effect among N, Cr and Mo. Meanwhile, the conversion products of NH4+ or NO3- from N element can effectively inhibit the formation of secondary corrosion pits in 316LN stainless steel and avoid rapid propagation of corrosion pits in depth.
In view of the current situation that the influence of N element on the pitting corrosion resistance of austenitic stainless steel and its mechanism are not clear, the mechanical properties and electrochemical impedance spectroscopy of nitrogen controlled stainless steel 316LN are tested. The results showed that the mechanical properties and corrosion resistance of 316LN at room temperature were superior to those of 316L stainless steel, but the corrosion resistance of 316LN stainless steel was degraded significantly with the increasing of temperature and medium concentration. At room temperature and low concentration of chloride ion, the impedance of the passivation film on 316LN stainless steel is higher than that of 316L stainless steel, which indicated that the stability of the passivation film on 316LN stainless steel is higher than that of 316L stainless steel under the synergistic effect among N, Cr and Mo. Meanwhile, the conversion products of NH4+ or NO3- from N element can effectively inhibit the formation of secondary corrosion pits in 316LN stainless steel and avoid rapid propagation of corrosion pits in depth.
2024, 43(6): 1092-1100.
doi: 10.13433/j.cnki.1003-8728.20230237
Abstract:
Thermal-structural test is an indispensable verification step in the development of hypersonic vehicle. Based on the connotation and characteristics of thermal-structural test, combined with an introduction to some typical subjects of thermal-structural test, this article presents the overall architecture of the thermal-structural test system, providing a reference for a comprehensive understanding of thermal-structural test; Secondly, it focuses on the analysis of seven key technologies urgently needed to be breakthrough in current thermal-structural test, including the realization of time-varying ultra-high temperature thermal loads, large gradient simulation of local thermal load, and time/frequency domain load coordination.
Thermal-structural test is an indispensable verification step in the development of hypersonic vehicle. Based on the connotation and characteristics of thermal-structural test, combined with an introduction to some typical subjects of thermal-structural test, this article presents the overall architecture of the thermal-structural test system, providing a reference for a comprehensive understanding of thermal-structural test; Secondly, it focuses on the analysis of seven key technologies urgently needed to be breakthrough in current thermal-structural test, including the realization of time-varying ultra-high temperature thermal loads, large gradient simulation of local thermal load, and time/frequency domain load coordination.
