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RSS2023 Vol. 42, No. 10
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2023, 42(10): 1575-1582.
doi: 10.13433/j.cnki.1003-8728.20220136
PDF 3336KB
Abstract:
In this paper, the damping control strategy of eight-wheel heavy armored vehicle suspension was studied under non-Gaussian random road conditions. At present, the random road is usually characterized by Gaussian signal based on power spectral density method, which is difficult to exactly describe the complex road conditions of armored vehicles. First, the suspension model of the eight-wheel heavy armored vehicle was established; Second, the accurate characterization of non-Gaussian performance of undulating road was realized; Finally, a fuzzy adaptive suspension vibration control strategy on non-Gaussian random roads was proposed. The simulation results show that the proposed control strategy has a good damping effect on the armored vehicle under the actual road conditions, and lays a theoretical foundation for the damping control of the armored vehicle.
In this paper, the damping control strategy of eight-wheel heavy armored vehicle suspension was studied under non-Gaussian random road conditions. At present, the random road is usually characterized by Gaussian signal based on power spectral density method, which is difficult to exactly describe the complex road conditions of armored vehicles. First, the suspension model of the eight-wheel heavy armored vehicle was established; Second, the accurate characterization of non-Gaussian performance of undulating road was realized; Finally, a fuzzy adaptive suspension vibration control strategy on non-Gaussian random roads was proposed. The simulation results show that the proposed control strategy has a good damping effect on the armored vehicle under the actual road conditions, and lays a theoretical foundation for the damping control of the armored vehicle.
2023, 42(10): 1583-1591.
doi: 10.13433/j.cnki.1003-8728.20220121
Abstract:
In order to study the effects of different miller cycles on the combustion and performance of a high-power biogas engine on different conditions, based on the 1.15 MW supercharged biogas engine and its simulation model, the Otto cycle of the biogas engine was changed into different miller cycles by changing the timing of inlet valve closing. Simulation results show that the biogas engine's power output reaches the same target, as the early miller cycle gets earlier and the late miller cycle gets later. The maximum combustion pressure, maximum combustion temperature in the cylinder, its exhaust temperature, fuel consumption rate and nitrogen oxide emissions are reduced obviously. This suggests that the early miller cycle and late miller cycle of the gas engine's combustion and performance are improved. With the advance of the early miller cycle and the delay of the late miller cycle, in order to ensure the same output power, their pressure needs to be increased, but the charging efficiency obviously decreases. With the strengthening of the late miller cycle, the inlet backflow phenomenon occurs when the intake valve is closed, and the inlet backflow phenomenon easily occurs. No inlet backflow phenomenon occurs when the intake valve of the early miller cycle is closed. Compared with the late miller cycle, the early miller cycle is more suitable for the intake mixture demand of a premixed and supercharged gas engine. The explosion pressure, gas consumption rate and nitrogen oxide emission of the miller cycle studied in this paper decrease by 3.74 %, 2.49 % and 23.58 % respectively, thus reducing its detonation and emissions and improving its efficiency.
In order to study the effects of different miller cycles on the combustion and performance of a high-power biogas engine on different conditions, based on the 1.15 MW supercharged biogas engine and its simulation model, the Otto cycle of the biogas engine was changed into different miller cycles by changing the timing of inlet valve closing. Simulation results show that the biogas engine's power output reaches the same target, as the early miller cycle gets earlier and the late miller cycle gets later. The maximum combustion pressure, maximum combustion temperature in the cylinder, its exhaust temperature, fuel consumption rate and nitrogen oxide emissions are reduced obviously. This suggests that the early miller cycle and late miller cycle of the gas engine's combustion and performance are improved. With the advance of the early miller cycle and the delay of the late miller cycle, in order to ensure the same output power, their pressure needs to be increased, but the charging efficiency obviously decreases. With the strengthening of the late miller cycle, the inlet backflow phenomenon occurs when the intake valve is closed, and the inlet backflow phenomenon easily occurs. No inlet backflow phenomenon occurs when the intake valve of the early miller cycle is closed. Compared with the late miller cycle, the early miller cycle is more suitable for the intake mixture demand of a premixed and supercharged gas engine. The explosion pressure, gas consumption rate and nitrogen oxide emission of the miller cycle studied in this paper decrease by 3.74 %, 2.49 % and 23.58 % respectively, thus reducing its detonation and emissions and improving its efficiency.
2023, 42(10): 1592-1601.
doi: 10.13433/j.cnki.1003-8728.20220063
Abstract:
In order to improve the anti-vibration performance of a pipe winch barrel, the vibration characteristics of the three-hole winch barrel were analyzed, and the dynamic optimization of the winch barrel was studied based on the response surface method. Firstly, based on the finite element model of the three-hole winch barrel, the natural frequency, vibration mode and relationship between frequency of the cylinder and its amplitude were obtained with prestressed loading, modal analysis and harmonic response analysis. The comparison of modal analysis results with harmonic response analysis results finds that the first two natural frequencies have a great influence on the winch barrel and easily cause resonance. The study of the influence of the number of holes on the cylinder shows that the natural frequency of the two-hole cylinder is higher. The design variables were screened with sensitivity analysis, and sample points were obtained with the face-centered composite design. The Kriging response surface model was constructed to optimize the structural and material parameters. The results show that compared with the original three-hole winch barrel, the first two natural frequencies of the optimized winch barrel increase by 189% and 359.7% respectively and that the mass of the optimized winch barrel decreases by 39%.
In order to improve the anti-vibration performance of a pipe winch barrel, the vibration characteristics of the three-hole winch barrel were analyzed, and the dynamic optimization of the winch barrel was studied based on the response surface method. Firstly, based on the finite element model of the three-hole winch barrel, the natural frequency, vibration mode and relationship between frequency of the cylinder and its amplitude were obtained with prestressed loading, modal analysis and harmonic response analysis. The comparison of modal analysis results with harmonic response analysis results finds that the first two natural frequencies have a great influence on the winch barrel and easily cause resonance. The study of the influence of the number of holes on the cylinder shows that the natural frequency of the two-hole cylinder is higher. The design variables were screened with sensitivity analysis, and sample points were obtained with the face-centered composite design. The Kriging response surface model was constructed to optimize the structural and material parameters. The results show that compared with the original three-hole winch barrel, the first two natural frequencies of the optimized winch barrel increase by 189% and 359.7% respectively and that the mass of the optimized winch barrel decreases by 39%.
2023, 42(10): 1602-1608.
doi: 10.13433/j.cnki.1003-8728.20220127
Abstract:
This paper proposes a lightweight origami gripper based on the waterbomb origami principle. Firstly, the structure of a waterbomb is introduced and its geometry is analyzed. The foldable conditions for forming the waterbomb′s cylinder are obtained, and the gripping device design and manufacturing method are presented. The gripping experimental platform of the origami gripper was built. The gripping and lifting of objects with different geometries, textures and weights were tested. The gripper′s axial offset gripping capability was also tested, and the relationship between the gripper′s load capacity and air pressure was analyzed. The experiments on gripping show that the flexible gripper has the advantage of axial offset gripping, shape adaptive gripping and controllable gripping force. It is useful to grasp and sort flexible and light objects such as food and fruits.
This paper proposes a lightweight origami gripper based on the waterbomb origami principle. Firstly, the structure of a waterbomb is introduced and its geometry is analyzed. The foldable conditions for forming the waterbomb′s cylinder are obtained, and the gripping device design and manufacturing method are presented. The gripping experimental platform of the origami gripper was built. The gripping and lifting of objects with different geometries, textures and weights were tested. The gripper′s axial offset gripping capability was also tested, and the relationship between the gripper′s load capacity and air pressure was analyzed. The experiments on gripping show that the flexible gripper has the advantage of axial offset gripping, shape adaptive gripping and controllable gripping force. It is useful to grasp and sort flexible and light objects such as food and fruits.
2023, 42(10): 1609-1616.
doi: 10.13433/j.cnki.1003-8728.20220142
Abstract:
Because the pneumatic position servo friction will cause the dynamic hysteresis of the system, especially the cylinder piston is prone to "flat top" phenomenon in the commutation process, so it is necessary to compensate the friction for the pneumatic system. However, due to the parameter uncertainties and strong nonlinearities of the pneumatic system, the effect of the friction compensation will be reduced. System is subjected to coupling of the two chambers of the cylinder and saturation of gas flow, which will cause the control system to have a low degree of freedom, and a large energy loss. In response to the above problems, the LuGre model is used to characterize the friction dynamics well, to describe the cylinder friction and propose an adaptive robust controller for friction compensation. The adaptive part of the controller is used to control parameter uncertainties. The robust part is used to deal with the nonlinearities of the system. Two three-position four-way proportional valves are applied to increase the control degrees of freedom and reduce the energy dissipation. The simulation illustrate that the compensation strategy effectively improves the dynamic lag, and improves the dynamic response and tracking accuracy of the system.
Because the pneumatic position servo friction will cause the dynamic hysteresis of the system, especially the cylinder piston is prone to "flat top" phenomenon in the commutation process, so it is necessary to compensate the friction for the pneumatic system. However, due to the parameter uncertainties and strong nonlinearities of the pneumatic system, the effect of the friction compensation will be reduced. System is subjected to coupling of the two chambers of the cylinder and saturation of gas flow, which will cause the control system to have a low degree of freedom, and a large energy loss. In response to the above problems, the LuGre model is used to characterize the friction dynamics well, to describe the cylinder friction and propose an adaptive robust controller for friction compensation. The adaptive part of the controller is used to control parameter uncertainties. The robust part is used to deal with the nonlinearities of the system. Two three-position four-way proportional valves are applied to increase the control degrees of freedom and reduce the energy dissipation. The simulation illustrate that the compensation strategy effectively improves the dynamic lag, and improves the dynamic response and tracking accuracy of the system.
2023, 42(10): 1617-1624.
doi: 10.13433/j.cnki.1003-8728.20220145
Abstract:
In order to improve the impact resistance of the battery pack box, the battery pack of a certain logistics vehicle was taken as the research object, and the dynamic analysis of the battery pack under drop and extrusion conditions was carried out. The effects of different drop height, drop angle and extrusion direction on the dynamic response of battery pack box were analyzed. According to the analysis result, with the safety performance of the battery pack box as the optimization purpose, and the size parameters of the battery pack box as the design variable, the multi-objective size optimization of the battery pack box was performed, and the optimization effect was verified by the drop test. The results show that the strength of the battery pack box is improved after optimization, and the dynamic response meets the requirements of drop and extrusion conditions, which verifies the correctness of the battery pack structure optimization design method in this paper.
In order to improve the impact resistance of the battery pack box, the battery pack of a certain logistics vehicle was taken as the research object, and the dynamic analysis of the battery pack under drop and extrusion conditions was carried out. The effects of different drop height, drop angle and extrusion direction on the dynamic response of battery pack box were analyzed. According to the analysis result, with the safety performance of the battery pack box as the optimization purpose, and the size parameters of the battery pack box as the design variable, the multi-objective size optimization of the battery pack box was performed, and the optimization effect was verified by the drop test. The results show that the strength of the battery pack box is improved after optimization, and the dynamic response meets the requirements of drop and extrusion conditions, which verifies the correctness of the battery pack structure optimization design method in this paper.
2023, 42(10): 1625-1629.
doi: 10.13433/j.cnki.1003-8728.20220129
Abstract:
Aiming at the positioning feature of parking robot, by using inertial navigation, odometer and two-dimensional code module, a parking robot positioning system was developed based on Visual C + + platform. The speed geometry method was adopted and the robot kinematic model was established. On this basis, the attitude transformation matrix of inertial navigation sensor data was derived, and the odometer sensor motion model was established. Combined Kalman filter method with kinematic dead reckoning, a multi-sensor combined positioning method was proposed. The positioning experiment of parking robot shows that, the parking robot that adopts multi-sensor combined positioning method can better realize the operation; Compared with dead reckoning positioning method, its average positioning deviation is reduced by 92%, reaching 14.04 mm, and the positioning accuracy is significantly improved, which can better meet the positioning requirements of parking robot.
Aiming at the positioning feature of parking robot, by using inertial navigation, odometer and two-dimensional code module, a parking robot positioning system was developed based on Visual C + + platform. The speed geometry method was adopted and the robot kinematic model was established. On this basis, the attitude transformation matrix of inertial navigation sensor data was derived, and the odometer sensor motion model was established. Combined Kalman filter method with kinematic dead reckoning, a multi-sensor combined positioning method was proposed. The positioning experiment of parking robot shows that, the parking robot that adopts multi-sensor combined positioning method can better realize the operation; Compared with dead reckoning positioning method, its average positioning deviation is reduced by 92%, reaching 14.04 mm, and the positioning accuracy is significantly improved, which can better meet the positioning requirements of parking robot.
2023, 42(10): 1630-1637.
doi: 10.13433/j.cnki.1003-8728.20220124
Abstract:
The joint friction pair of excavator working device is directly related to the operation quality and product reliability of excavator. Aiming at the joint friction pair ear plate eversion and end face wear in the use of excavator, the dynamic model for working device is established, and the dynamic simulation is carried out via ADAMS to obtain the load spectrum of three main load-bearing joints of working device. At the same time, it is verified by using the strain gauge experiment to ensure the correctness of dynamic simulation results. Based on the load spectrum of dynamic simulation results, the dynamic contact characteristics of boom base joint of working device are simulated and analyzed by using ANSYS. The results show that the working device has a large sudden load at the start and end of the excavation process, which has an impact on the ear plate, the failure of joint end face is caused by fatigue failure, the contact wear area is mainly concentrated at the outer edge of one end face. With the adhesion between them, the wear of the end face will gradually extend from the outside to the inside. The conclusions provide a basis for the impact, wear analysis and joint contact optimization of the joint end face of the excavator working device.
The joint friction pair of excavator working device is directly related to the operation quality and product reliability of excavator. Aiming at the joint friction pair ear plate eversion and end face wear in the use of excavator, the dynamic model for working device is established, and the dynamic simulation is carried out via ADAMS to obtain the load spectrum of three main load-bearing joints of working device. At the same time, it is verified by using the strain gauge experiment to ensure the correctness of dynamic simulation results. Based on the load spectrum of dynamic simulation results, the dynamic contact characteristics of boom base joint of working device are simulated and analyzed by using ANSYS. The results show that the working device has a large sudden load at the start and end of the excavation process, which has an impact on the ear plate, the failure of joint end face is caused by fatigue failure, the contact wear area is mainly concentrated at the outer edge of one end face. With the adhesion between them, the wear of the end face will gradually extend from the outside to the inside. The conclusions provide a basis for the impact, wear analysis and joint contact optimization of the joint end face of the excavator working device.
2023, 42(10): 1638-1647.
doi: 10.13433/j.cnki.1003-8728.20220131
Abstract:
Under the cyclic compound action of multiple loads, such as axial, bending and torque loads, crack initiation and fatigue crack propagation occur at the stress concentration position or defect of the pipe body, and lead to failure or even fracture of the pipe body. The API S135 steel drill pipe body was taken as the research object, the mechanical properties of the material were tested by using the uniaxial tensile test and crack propagation test, the simulation model for the drill pipe body was established, and the fatigue failure cases of API S135 steel grade drill pipe were taken as the object to verify the feasibility of the simulation model. Through the numerical simulation of crack propagation, it is found that the thickening transition zone inside the pipe body is the most prone to fracture failure, and the load cycle times are the lowest. The increase in load stress ratio can reduce the risk of fatigue fracture. The conclusions are obtained that by improving the structural design of the thickening transition zone in the drill pipe body: the maximum Mises stress and the number of load cycles are slightly affected by modifying the inside and outside thickening cone lengths, the Mises stress decreases significantly and the number of load cycles increases significantly after increasing wall thickness of the drill pipe body, therefore, increasing wall thickness of the drill pipe body is a more effective improved method, and the structural combination is analyzed and optimized by using the orthogonal experiment.
Under the cyclic compound action of multiple loads, such as axial, bending and torque loads, crack initiation and fatigue crack propagation occur at the stress concentration position or defect of the pipe body, and lead to failure or even fracture of the pipe body. The API S135 steel drill pipe body was taken as the research object, the mechanical properties of the material were tested by using the uniaxial tensile test and crack propagation test, the simulation model for the drill pipe body was established, and the fatigue failure cases of API S135 steel grade drill pipe were taken as the object to verify the feasibility of the simulation model. Through the numerical simulation of crack propagation, it is found that the thickening transition zone inside the pipe body is the most prone to fracture failure, and the load cycle times are the lowest. The increase in load stress ratio can reduce the risk of fatigue fracture. The conclusions are obtained that by improving the structural design of the thickening transition zone in the drill pipe body: the maximum Mises stress and the number of load cycles are slightly affected by modifying the inside and outside thickening cone lengths, the Mises stress decreases significantly and the number of load cycles increases significantly after increasing wall thickness of the drill pipe body, therefore, increasing wall thickness of the drill pipe body is a more effective improved method, and the structural combination is analyzed and optimized by using the orthogonal experiment.
2023, 42(10): 1648-1656.
doi: 10.13433/j.cnki.1003-8728.20220120
Abstract:
To improve the performance of hydrogen-doped natural gas homogeneous compression-ignition (HCCI) engine and reduce NOx emissions, a coupled simulation model of HCCI engine was built based on GT-power and Chemkin software and using negative valve overlap (NVO) strategy. The in-cylinder combustion and NOx emission were simulated for different scenarios of NVO. The results show that the NVO strategy can reduce the peak in-cylinder temperature and pressure, improve the auto-ignition ignition characteristics, and mitigate noise and detonation in hydrogen-doped natural gas HCCI engines. Among the three schemes, the NVO strategy that changes the intake valve opening (IVO) moment alone has the least effect on engine power loss, and the symmetric NVO strategy that changes the IVO and EVC moments simultaneously can maximize the in-cylinder dilution effect and heating effect of exhaust gas, optimize the moderating effect of in-cylinder combustion exothermic rate and the reduction effect of pressure rise rate, and minimize NOx emission.
To improve the performance of hydrogen-doped natural gas homogeneous compression-ignition (HCCI) engine and reduce NOx emissions, a coupled simulation model of HCCI engine was built based on GT-power and Chemkin software and using negative valve overlap (NVO) strategy. The in-cylinder combustion and NOx emission were simulated for different scenarios of NVO. The results show that the NVO strategy can reduce the peak in-cylinder temperature and pressure, improve the auto-ignition ignition characteristics, and mitigate noise and detonation in hydrogen-doped natural gas HCCI engines. Among the three schemes, the NVO strategy that changes the intake valve opening (IVO) moment alone has the least effect on engine power loss, and the symmetric NVO strategy that changes the IVO and EVC moments simultaneously can maximize the in-cylinder dilution effect and heating effect of exhaust gas, optimize the moderating effect of in-cylinder combustion exothermic rate and the reduction effect of pressure rise rate, and minimize NOx emission.
2023, 42(10): 1657-1664.
doi: 10.13433/j.cnki.1003-8728.20220133
Abstract:
Based on the combination of positive and reverse grey-bootstrap filtering methods, the effective bearing performance degradation information can be extracted to accurately calculate the performance reliability of bearings in the operation process. The positive and reverse grey-bootstrap filtering methods were used to denoise the collected vibration acceleration data of rolling bearings respectively, which were fused to obtain the new data series. Based on the probability density function-intersection method, the intersection area of probability density functions was taken as a new index to quantitatively evaluate the filtering effect for the data series before and after filtering. The performance threshold was selected to calculate the variation number, variation probability and performance reliability of data series. The variation degree of bearing performance in the operation process was analyzed quantitatively. Both cases show that the combined positive and reverse grey-bootstrap filtering method has the best filtering effect, and It is feasible to use it to evaluate the performance degradation process of rolling bearings.
Based on the combination of positive and reverse grey-bootstrap filtering methods, the effective bearing performance degradation information can be extracted to accurately calculate the performance reliability of bearings in the operation process. The positive and reverse grey-bootstrap filtering methods were used to denoise the collected vibration acceleration data of rolling bearings respectively, which were fused to obtain the new data series. Based on the probability density function-intersection method, the intersection area of probability density functions was taken as a new index to quantitatively evaluate the filtering effect for the data series before and after filtering. The performance threshold was selected to calculate the variation number, variation probability and performance reliability of data series. The variation degree of bearing performance in the operation process was analyzed quantitatively. Both cases show that the combined positive and reverse grey-bootstrap filtering method has the best filtering effect, and It is feasible to use it to evaluate the performance degradation process of rolling bearings.
2023, 42(10): 1665-1672.
doi: 10.13433/j.cnki.1003-8728.20220134
Abstract:
Superhydrophobic surface has many excellent properties, such as self-cleaning, antifreeze. It has a wide application prospect in aerospace, weapon equipment and other fields. In order to solve the problem that the traditional superhydrophobic surface has high-cost and poor-wear resistance in the complex preparation process, a new method of one-step fabrication and multi-level hierarchical structure formation of discharge pits / bulges surface morphology with wire electrical discharge machining (WEDM) is proposed. We study the surface characteristics of the workpiece processed with WEDM under specific parameters, obtain its surface contact angle (CA) and microstructure. Then, we design the dimensions of three different surface textures and predict their actual sizes. We also establish the CA simulation model, carry out the simulations and analyze the influence of surface texture type and size on the CA. Finally, we do experiments on CAs. The experimental results show that the maximum contact angle is 152.5° and that the error between predicted CA and experimental values is less than 6%.
Superhydrophobic surface has many excellent properties, such as self-cleaning, antifreeze. It has a wide application prospect in aerospace, weapon equipment and other fields. In order to solve the problem that the traditional superhydrophobic surface has high-cost and poor-wear resistance in the complex preparation process, a new method of one-step fabrication and multi-level hierarchical structure formation of discharge pits / bulges surface morphology with wire electrical discharge machining (WEDM) is proposed. We study the surface characteristics of the workpiece processed with WEDM under specific parameters, obtain its surface contact angle (CA) and microstructure. Then, we design the dimensions of three different surface textures and predict their actual sizes. We also establish the CA simulation model, carry out the simulations and analyze the influence of surface texture type and size on the CA. Finally, we do experiments on CAs. The experimental results show that the maximum contact angle is 152.5° and that the error between predicted CA and experimental values is less than 6%.
2023, 42(10): 1673-1677.
doi: 10.13433/j.cnki.1003-8728.20220123
Abstract:
Traditional 3D printing technology wastes a lot of time and materials in the generating and removing of the auxiliary support structure for building complex models. To solve this problem, a five axis 3D printing algorithm based on model decomposition is proposed, which makes it possible to print models with supported structure reduction. The algorithm can firstly decompose a model with layer-slicing method and maintain a multiple decomposition tree with each node saving a relevant model information. According to the structure of the multiple decomposition tree and its corresponding information, the printing path of the five axis device can be planned. With the help of five axis manufacturing system, the algorithm can decompose some normal models to print with the supported structure reduction.
Traditional 3D printing technology wastes a lot of time and materials in the generating and removing of the auxiliary support structure for building complex models. To solve this problem, a five axis 3D printing algorithm based on model decomposition is proposed, which makes it possible to print models with supported structure reduction. The algorithm can firstly decompose a model with layer-slicing method and maintain a multiple decomposition tree with each node saving a relevant model information. According to the structure of the multiple decomposition tree and its corresponding information, the printing path of the five axis device can be planned. With the help of five axis manufacturing system, the algorithm can decompose some normal models to print with the supported structure reduction.
2023, 42(10): 1678-1689.
doi: 10.13433/j.cnki.1003-8728.20220122
Abstract:
In order to effectively identify the tool wear states in the drilling process and provide timely warning of tool wear for the actual machining process in the factory, a condition monitoring platform for tool wear state of drilling based on LabVIEW is developed. The platform can realize real-time vibration signal acquisition, feature extraction and data preservation in time domain, frequency domain and time-frequency domain. By combining genetic optimization algorithm (GA), Back propagation (BP) neural network and ensemble learning, the GA-BP-Adaboost model is constructed, and the model is built by LabVIEW and MATLAB mixed programming. Finally, through actual drilling experiments, the characterization of real-time signals and their various characteristics on the wear states of drill tools is analyzed, the 1, 6 and 8 frequency bands of three-layer wavelet packet decomposition are selected as the input data of the model to train the GA-BP-Adaboost model, the classification accuracy of the model is above 90%. At the same time, the real-time response time of the platform is not more than 3 seconds, which can meet the requirements of the actual machining process.
In order to effectively identify the tool wear states in the drilling process and provide timely warning of tool wear for the actual machining process in the factory, a condition monitoring platform for tool wear state of drilling based on LabVIEW is developed. The platform can realize real-time vibration signal acquisition, feature extraction and data preservation in time domain, frequency domain and time-frequency domain. By combining genetic optimization algorithm (GA), Back propagation (BP) neural network and ensemble learning, the GA-BP-Adaboost model is constructed, and the model is built by LabVIEW and MATLAB mixed programming. Finally, through actual drilling experiments, the characterization of real-time signals and their various characteristics on the wear states of drill tools is analyzed, the 1, 6 and 8 frequency bands of three-layer wavelet packet decomposition are selected as the input data of the model to train the GA-BP-Adaboost model, the classification accuracy of the model is above 90%. At the same time, the real-time response time of the platform is not more than 3 seconds, which can meet the requirements of the actual machining process.
2023, 42(10): 1690-1698.
doi: 10.13433/j.cnki.1003-8728.20220119
Abstract:
In evaluating the reliability of a non-failure data link, it is difficult to estimate the points of parameters and their confidence interval at the same time by using a single model, and different methods for point and interval estimation may cause the inconsistency of results. This paper carried out the reliability analysis of the packing link of a cryogenic valve under the condition of non-failure data. A point estimation method of product reliability was proposed with the multilayer Bayes method. Samples were extracted from product life probability distribution with the bootstrap sampling method. Combined with the moment method, a reliability modeling method for estimating the interval reliability of the packing link of a cryogenic valve is obtained. The method was based on actual operation conditions to determine the value of the range parameter c with the multilayer Bayes method. Thus, the service life of the cryogenic valve′s packing link probability distribution curve was extracted from the life probability distribution of new samples through reusing the bootstrap method. New samples of the cryogenic valve′s packing link reliability interval estimation were obtained with the moment method. The results are compared with the interval estimation by using the confidence limit method. They show that the new model improves the accuracy of reliability interval estimation under the Weibull distribution, providing a theoretical basis for the reliability evaluation of non-failure data links.
In evaluating the reliability of a non-failure data link, it is difficult to estimate the points of parameters and their confidence interval at the same time by using a single model, and different methods for point and interval estimation may cause the inconsistency of results. This paper carried out the reliability analysis of the packing link of a cryogenic valve under the condition of non-failure data. A point estimation method of product reliability was proposed with the multilayer Bayes method. Samples were extracted from product life probability distribution with the bootstrap sampling method. Combined with the moment method, a reliability modeling method for estimating the interval reliability of the packing link of a cryogenic valve is obtained. The method was based on actual operation conditions to determine the value of the range parameter c with the multilayer Bayes method. Thus, the service life of the cryogenic valve′s packing link probability distribution curve was extracted from the life probability distribution of new samples through reusing the bootstrap method. New samples of the cryogenic valve′s packing link reliability interval estimation were obtained with the moment method. The results are compared with the interval estimation by using the confidence limit method. They show that the new model improves the accuracy of reliability interval estimation under the Weibull distribution, providing a theoretical basis for the reliability evaluation of non-failure data links.
2023, 42(10): 1699-1704.
doi: 10.13433/j.cnki.1003-8728.20220146
Abstract:
The deep residual network can use skip connections to directly pass the input information to the output, so it can build a deeper layer to improve the training effect of the neural network; but in complex working conditions, the influence of redundant noise will make the diagnostic performance of residual network drop significantly. Considering the noise reduction performance of the soft threshold and the adaptive screening feature performance of the attention mechanism, a set of adaptive threshold blocks are embedded in the residual module, which utilizes the attention mechanism to weight the features according to different degrees of importance and automatically set different thresholds for each sample to eliminate the interference of random noise on fault diagnosis. Furtherly, considering that the gearbox fault signal is highly time-varying, and the features learned by the CNN model have a certain scale invariance, a multi-scale convolution kernel and a feature fusion model are proposed to improve the network model, which significantly improves the phenomenon of feature loss. The final experiment shows that in the case of noise, the accuracy of the improved model is significantly improved; after adding multi-scale feature fusion, the number of iterations required by the network is greatly reduced, and the fault diagnosis accuracy of the improved network is further increased by 2 percentage points. Efficiency of network learning is significantly increased by 40%.
The deep residual network can use skip connections to directly pass the input information to the output, so it can build a deeper layer to improve the training effect of the neural network; but in complex working conditions, the influence of redundant noise will make the diagnostic performance of residual network drop significantly. Considering the noise reduction performance of the soft threshold and the adaptive screening feature performance of the attention mechanism, a set of adaptive threshold blocks are embedded in the residual module, which utilizes the attention mechanism to weight the features according to different degrees of importance and automatically set different thresholds for each sample to eliminate the interference of random noise on fault diagnosis. Furtherly, considering that the gearbox fault signal is highly time-varying, and the features learned by the CNN model have a certain scale invariance, a multi-scale convolution kernel and a feature fusion model are proposed to improve the network model, which significantly improves the phenomenon of feature loss. The final experiment shows that in the case of noise, the accuracy of the improved model is significantly improved; after adding multi-scale feature fusion, the number of iterations required by the network is greatly reduced, and the fault diagnosis accuracy of the improved network is further increased by 2 percentage points. Efficiency of network learning is significantly increased by 40%.
2023, 42(10): 1705-1711.
doi: 10.13433/j.cnki.1003-8728.20220132
Abstract:
In order to realize the multi-objective optimization of the energy efficiency and machining quality of CNC lathes, a ACOR optimization algorithm (Black hole-continuous ant colony) for optimizing the turning parameters is proposed. Firstly, with the minimum cutting specific energy and minimum surface roughness as the optimization goals, a multi-objective optimization model for the material cutting stage of the CNC lathe was established; secondly, the black hole algorithm was introduced to improve the continuous ant colony algorithm, and a black hole-continuous ant colony algorithm for multi-objective optimization was constructed; finally, the black hole-continuous ant colony algorithm is used to optimize the cutting parameters of the CNC lathe in the cutting stage, and the optimization results are compared and analyzed with that by using the other optimization algorithms. The analysis results show that the black hole-continuous ant colony algorithm not only has good global search capabilities, but also has improved optimization capabilities comparing with the other algorithms. It can provide new solutions for the manufacturing industry to improve the production energy efficiency and processing quality.
In order to realize the multi-objective optimization of the energy efficiency and machining quality of CNC lathes, a ACOR optimization algorithm (Black hole-continuous ant colony) for optimizing the turning parameters is proposed. Firstly, with the minimum cutting specific energy and minimum surface roughness as the optimization goals, a multi-objective optimization model for the material cutting stage of the CNC lathe was established; secondly, the black hole algorithm was introduced to improve the continuous ant colony algorithm, and a black hole-continuous ant colony algorithm for multi-objective optimization was constructed; finally, the black hole-continuous ant colony algorithm is used to optimize the cutting parameters of the CNC lathe in the cutting stage, and the optimization results are compared and analyzed with that by using the other optimization algorithms. The analysis results show that the black hole-continuous ant colony algorithm not only has good global search capabilities, but also has improved optimization capabilities comparing with the other algorithms. It can provide new solutions for the manufacturing industry to improve the production energy efficiency and processing quality.
2023, 42(10): 1712-1718.
doi: 10.13433/j.cnki.1003-8728.20220148
Abstract:
Since the water-film pressure wireless monitoring node of water-lubricated bearing is installed coaxially and rotating with the shaft at high speed, its power supply becomes vital importance and difficult. To solve the above problems, a contactless power supply method was proposed in this study, the physical model of coupling mechanism and its equivalent circuit were established, and its characteristics were analyzed. Then, the primary and secondary side circuits of the coupling mechanism are compensated, further the output power and efficiency are simulated. Finally, it is verified by experiment. The results show that the simulation results are in good agreement with the experimental results. After SP compensation, the average output power of the coupling mechanism is 10.332 W, and the transmission efficiency is 69.84%, which can meet the requirements of contactless power supply for wireless monitoring nodes.
Since the water-film pressure wireless monitoring node of water-lubricated bearing is installed coaxially and rotating with the shaft at high speed, its power supply becomes vital importance and difficult. To solve the above problems, a contactless power supply method was proposed in this study, the physical model of coupling mechanism and its equivalent circuit were established, and its characteristics were analyzed. Then, the primary and secondary side circuits of the coupling mechanism are compensated, further the output power and efficiency are simulated. Finally, it is verified by experiment. The results show that the simulation results are in good agreement with the experimental results. After SP compensation, the average output power of the coupling mechanism is 10.332 W, and the transmission efficiency is 69.84%, which can meet the requirements of contactless power supply for wireless monitoring nodes.
2023, 42(10): 1719-1726.
doi: 10.13433/j.cnki.1003-8728.20220302
Abstract:
Reconstructing the vehicle braking process again and judging the late braking period plays a decisive role in vehicle braking comfort. To control the longitudinal braking condition, it is necessary to re-plan the acceleration and speed in the later braking period, in which the speed planning adopts the form of quadratic curve. After speed planning, the impact degree (the time change rate of acceleration) when the vehicle brakes is obviously reduced. The correctness of the algorithm is verified in MATLAB software, and the optimization results at the vehicle level are obtained through the joint simulation of Simulink and Carsim. Aiming at the problems of braking comfort and braking safety, the solution of "decompression-pressure maintaining-pressure increasing" of the braking system is put forward, and the real vehicle test is carried out. The test results show that all evaluation indexes are good, and the braking comfortableness is improved while ensuring the safety.
Reconstructing the vehicle braking process again and judging the late braking period plays a decisive role in vehicle braking comfort. To control the longitudinal braking condition, it is necessary to re-plan the acceleration and speed in the later braking period, in which the speed planning adopts the form of quadratic curve. After speed planning, the impact degree (the time change rate of acceleration) when the vehicle brakes is obviously reduced. The correctness of the algorithm is verified in MATLAB software, and the optimization results at the vehicle level are obtained through the joint simulation of Simulink and Carsim. Aiming at the problems of braking comfort and braking safety, the solution of "decompression-pressure maintaining-pressure increasing" of the braking system is put forward, and the real vehicle test is carried out. The test results show that all evaluation indexes are good, and the braking comfortableness is improved while ensuring the safety.
2023, 42(10): 1727-1734.
doi: 10.13433/j.cnki.1003-8728.20220126
Abstract:
Based on the working principle of the three-position anti-skid valve of the rolling stock braking system, a mathematical model of the anti-skid valve is established, and the simulation analysis of the charging and exhaust characteristics is carried out; And the mathematical models of electro-pneumatic switching valves, emergency valves, and relay valves are established in order to construct air brake unit models; Then, for the brake anti-skid control system, the anti-skid control unit and brake dynamics unit models are established, combined with the air brake unit model to build a four-axle vehicle braking anti-skid control numerical simulation platform. Finally, the numerical simulation platform is used to simulate and analyze the braking anti-skid performance of the train, and compare with actual vehicle online test data through three indicators of braking distance, vehicle speed and slippage error. The results show that: the error between the braking distance simulation value and the test value is less than 5%; The vehicle speed simulation curve and the test curve are in good agreement, and the difference between the two at any time is less than 3 km/h; The average value of slippage error in each sliding interval is less than 20%. All three meet the indicator requirements, verifying the effectiveness of the built four-axle vehicle brake anti-skid control model.
Based on the working principle of the three-position anti-skid valve of the rolling stock braking system, a mathematical model of the anti-skid valve is established, and the simulation analysis of the charging and exhaust characteristics is carried out; And the mathematical models of electro-pneumatic switching valves, emergency valves, and relay valves are established in order to construct air brake unit models; Then, for the brake anti-skid control system, the anti-skid control unit and brake dynamics unit models are established, combined with the air brake unit model to build a four-axle vehicle braking anti-skid control numerical simulation platform. Finally, the numerical simulation platform is used to simulate and analyze the braking anti-skid performance of the train, and compare with actual vehicle online test data through three indicators of braking distance, vehicle speed and slippage error. The results show that: the error between the braking distance simulation value and the test value is less than 5%; The vehicle speed simulation curve and the test curve are in good agreement, and the difference between the two at any time is less than 3 km/h; The average value of slippage error in each sliding interval is less than 20%. All three meet the indicator requirements, verifying the effectiveness of the built four-axle vehicle brake anti-skid control model.
2023, 42(10): 1735-1744.
doi: 10.13433/j.cnki.1003-8728.20220125
Abstract:
Nonlinear vibration characteristics of functionally graded materials plates in transverse load and thermal environment are investigated. Based on the Hamilton principle, Reddy's three order shear deformation theory and Von-Karman theory are employed to establish the nonlinear vibration equation, in which the physical properties vary with the temperature and the material composition distribution obeys a power-law principle. The partial differential equations are truncated into the ordinary differential equations with the Galerkin method, and the multi-scale method is used to obtain the solution of primary resonance of the nonlinear systems. The amplitude frequency response of plates with different parameters are discussed, and the multi-values and jumping phenomena are observed.
Nonlinear vibration characteristics of functionally graded materials plates in transverse load and thermal environment are investigated. Based on the Hamilton principle, Reddy's three order shear deformation theory and Von-Karman theory are employed to establish the nonlinear vibration equation, in which the physical properties vary with the temperature and the material composition distribution obeys a power-law principle. The partial differential equations are truncated into the ordinary differential equations with the Galerkin method, and the multi-scale method is used to obtain the solution of primary resonance of the nonlinear systems. The amplitude frequency response of plates with different parameters are discussed, and the multi-values and jumping phenomena are observed.
2023, 42(10): 1745-1752.
doi: 10.13433/j.cnki.1003-8728.20230296
Abstract:
The O-ring seal is an important component in aerospace seal structures, and its operating conditions are complex, which easily leads to seal failure and affects the normal operation of the system. This paper focuses on the selection and dynamic sealing failure of O-ring seals, and establishes a two-dimensional axisymmetric model of O-ring rubber seal based on ABAQUS to analyze the stress changes of different rubber material O-ring seals during reciprocating motion, and explore the effects of compression rate, friction coefficient, and medium pressure on the sealing performance, and predict the failure mode and location during reciprocating motion. The research shows that compared with Ethylene-Propylene-Diene monomer rubber and fluorous rubber, nitrile rubber O-ring seals have better sealing performance under the same conditions. During the precompression process, the O-ring rubber seal is compressed and deformed into a drum shape, and the maximum Von Mises stress appears at the contact position of the seal ring, the sealing groove, and the piston shaft. During reciprocating motion, the maximum Von Mises stress and maximum contact stress of O-ring rubber seals both increase with the increase of compression rate, friction coefficient and medium pressure; when the stroke ends, its maximum Von Mises stress value reaches a peak, and the peak value increases with the increase of friction coefficient; the maximum Von Mises stress and contact stress both increase with the increase of medium pressure, and stress concentration is prone to occur at the piston corner. This study can provide theoretical basis for material selection and dynamic sealing parameter control of O-ring rubber seals.
The O-ring seal is an important component in aerospace seal structures, and its operating conditions are complex, which easily leads to seal failure and affects the normal operation of the system. This paper focuses on the selection and dynamic sealing failure of O-ring seals, and establishes a two-dimensional axisymmetric model of O-ring rubber seal based on ABAQUS to analyze the stress changes of different rubber material O-ring seals during reciprocating motion, and explore the effects of compression rate, friction coefficient, and medium pressure on the sealing performance, and predict the failure mode and location during reciprocating motion. The research shows that compared with Ethylene-Propylene-Diene monomer rubber and fluorous rubber, nitrile rubber O-ring seals have better sealing performance under the same conditions. During the precompression process, the O-ring rubber seal is compressed and deformed into a drum shape, and the maximum Von Mises stress appears at the contact position of the seal ring, the sealing groove, and the piston shaft. During reciprocating motion, the maximum Von Mises stress and maximum contact stress of O-ring rubber seals both increase with the increase of compression rate, friction coefficient and medium pressure; when the stroke ends, its maximum Von Mises stress value reaches a peak, and the peak value increases with the increase of friction coefficient; the maximum Von Mises stress and contact stress both increase with the increase of medium pressure, and stress concentration is prone to occur at the piston corner. This study can provide theoretical basis for material selection and dynamic sealing parameter control of O-ring rubber seals.
2023, 42(10): 1753-1759.
doi: 10.13433/j.cnki.1003-8728.20230269
Abstract:
The quasi-static tensile mechanical properties tests at room temperature (25 ℃) and high temperature (150 ℃) were carried out for the three-nail bolted connection structures of aluminum alloys and carbon fiber reinforced polymers (CFRP) composites with different lap plate thicknesses, respectively. At the same time, a three-dimensional finite element model was established, and the Hashin failure criterion and progressive damage criterion were used for numerical simulation analysis, and the high temperature bearing characteristics and damage evolution law of the structure were obtained. The results show that for the connection structures of the three different aluminum alloy thicknesses D1, D2, and D3, the ultimate load test values at 150 ℃ relative to 25 ℃ were reduced by 6.63%, 13.07%, and 8.48%, respectively. The damages of the three structural destruction modes were aluminum alloy tensile fracture, composite extrusion failure, and composite tensile fracture at 25 ℃ respectively, while the three structural damage modes are the extrusion shear failure of the composite hole edge at 150 ℃.
The quasi-static tensile mechanical properties tests at room temperature (25 ℃) and high temperature (150 ℃) were carried out for the three-nail bolted connection structures of aluminum alloys and carbon fiber reinforced polymers (CFRP) composites with different lap plate thicknesses, respectively. At the same time, a three-dimensional finite element model was established, and the Hashin failure criterion and progressive damage criterion were used for numerical simulation analysis, and the high temperature bearing characteristics and damage evolution law of the structure were obtained. The results show that for the connection structures of the three different aluminum alloy thicknesses D1, D2, and D3, the ultimate load test values at 150 ℃ relative to 25 ℃ were reduced by 6.63%, 13.07%, and 8.48%, respectively. The damages of the three structural destruction modes were aluminum alloy tensile fracture, composite extrusion failure, and composite tensile fracture at 25 ℃ respectively, while the three structural damage modes are the extrusion shear failure of the composite hole edge at 150 ℃.
2023, 42(10): 1760-1766.
doi: 10.13433/j.cnki.1003-8728.20220128
Abstract:
Aiming at the severe vibration problems of turboprop aircraft engine, a medium power turboprop engine damping system was designed by using hydrogenated nitrile rubber (HNBR). By using the workbench ANSYS software, the dynamic modeling analysis method of the damping system with rubber solid element was studied. Then, taking the acceleration transmissibility as the evaluation criterion of vibration isolation performance, a medium power turboprop engine vibration reduction performance test system is designed, and the vibration reduction performance of the vibration reduction system is studied through the test method. The results show that under the assumption of small deformation, the elastic modulus of rubber material is estimated by the hardness of rubber material, and the dynamic simulation analysis of the damping system is carried out by simulating the rubber material with linear elastic model, and the difference between the simulation analysis results and the frequency sweep test results is below 10%; through the random vibration test, the vibration isolation efficiency of the damping system for the first-order narrow-band excitation of the engine is above 70%, and the vibration isolation efficiency for the second-order narrow-band excitation is above 85%. The designed damping system has the excellent vibration isolation effect for the narrow-band excitation of the engine.
Aiming at the severe vibration problems of turboprop aircraft engine, a medium power turboprop engine damping system was designed by using hydrogenated nitrile rubber (HNBR). By using the workbench ANSYS software, the dynamic modeling analysis method of the damping system with rubber solid element was studied. Then, taking the acceleration transmissibility as the evaluation criterion of vibration isolation performance, a medium power turboprop engine vibration reduction performance test system is designed, and the vibration reduction performance of the vibration reduction system is studied through the test method. The results show that under the assumption of small deformation, the elastic modulus of rubber material is estimated by the hardness of rubber material, and the dynamic simulation analysis of the damping system is carried out by simulating the rubber material with linear elastic model, and the difference between the simulation analysis results and the frequency sweep test results is below 10%; through the random vibration test, the vibration isolation efficiency of the damping system for the first-order narrow-band excitation of the engine is above 70%, and the vibration isolation efficiency for the second-order narrow-band excitation is above 85%. The designed damping system has the excellent vibration isolation effect for the narrow-band excitation of the engine.
