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RSS2023 Vol. 42, No. 2
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2023, 42(2): 165-172.
doi: 10.13433/j.cnki.1003-8728.20200614
PDF 1982KB
Abstract:
In the CNC machining, due to the factors such as the geometric and the installation error of the cutting tool, the random variations in the material properties of the workpiece and the cutter, the wearing process and the monitoring signals between the individual tools have large differences, which makes the tool wear values to difficultly predict. To address this problem, a multiscale time-distributed convolutional long short-term memory model (MTDCLSTM) combined with domain adversarial adaptation is proposed. With the multi-sensor signals obtained in the machining as the model input, the model extract multiscale spatio-temporal features that can effectively characterize the tool wear and are independent of the domain through the adversarial learning between the domain classifier and the predictor. The accurate prediction value of the tool wear can be obtained by using the non-linear mapping of the predictor. Experimental results show that the prediction performance of the MTDCLSTM model combined with domain adversarial adaptation is significantly better than the time-distributed convolutional neural networks, long short-term memory neural networks model, convolutional neural networks and support vector machine models. Comparing with the support vector regression model based on transfer component analysis, the root mean square error and average absolute error of the present model were reduced by 59.8% and 62.5%, respectively, and the coefficient of determination was increased by 66.1%, which means the present model can effectively reduce the difference between the individual tools and improve the accuracy of the wear prediction.
In the CNC machining, due to the factors such as the geometric and the installation error of the cutting tool, the random variations in the material properties of the workpiece and the cutter, the wearing process and the monitoring signals between the individual tools have large differences, which makes the tool wear values to difficultly predict. To address this problem, a multiscale time-distributed convolutional long short-term memory model (MTDCLSTM) combined with domain adversarial adaptation is proposed. With the multi-sensor signals obtained in the machining as the model input, the model extract multiscale spatio-temporal features that can effectively characterize the tool wear and are independent of the domain through the adversarial learning between the domain classifier and the predictor. The accurate prediction value of the tool wear can be obtained by using the non-linear mapping of the predictor. Experimental results show that the prediction performance of the MTDCLSTM model combined with domain adversarial adaptation is significantly better than the time-distributed convolutional neural networks, long short-term memory neural networks model, convolutional neural networks and support vector machine models. Comparing with the support vector regression model based on transfer component analysis, the root mean square error and average absolute error of the present model were reduced by 59.8% and 62.5%, respectively, and the coefficient of determination was increased by 66.1%, which means the present model can effectively reduce the difference between the individual tools and improve the accuracy of the wear prediction.
2023, 42(2): 173-180.
doi: 10.13433/j.cnki.1003-8728.20200597
Abstract:
Due to the unbalance quantity factors ofa high-speed gear shafting system,its gyroscopic effect may generate a large bending moment and cause potentially dangerous resonance. The high-speed input shafting model of a certain type of coaxial high-speed helicopter′s transmission system was established with the beam element method and the finite element method respectively. The vortex phenomenon of the high-speed gear shafting system with different vibration modes was systematically studied. Combined with its critical speed Campbell diagram, the freedom iscompared with the constraint modal under different influences of bearing stiffness on the critical speed value. The results show that the torsion and expansion modes of the high-speed gear shafting system do not produce vortices in free and constrained modes, while the transverse modes such as bendingdiameter and pitch diameter generate significant vortices, which are weakened in the constrained mode. The value of critical speed increases with the increase of the bearing stiffness of constrained modal. The critical speed of the high-speed shafting system can be accurately calculated with the bearing stiffness and the gyroscopic effect considered.
Due to the unbalance quantity factors ofa high-speed gear shafting system,its gyroscopic effect may generate a large bending moment and cause potentially dangerous resonance. The high-speed input shafting model of a certain type of coaxial high-speed helicopter′s transmission system was established with the beam element method and the finite element method respectively. The vortex phenomenon of the high-speed gear shafting system with different vibration modes was systematically studied. Combined with its critical speed Campbell diagram, the freedom iscompared with the constraint modal under different influences of bearing stiffness on the critical speed value. The results show that the torsion and expansion modes of the high-speed gear shafting system do not produce vortices in free and constrained modes, while the transverse modes such as bendingdiameter and pitch diameter generate significant vortices, which are weakened in the constrained mode. The value of critical speed increases with the increase of the bearing stiffness of constrained modal. The critical speed of the high-speed shafting system can be accurately calculated with the bearing stiffness and the gyroscopic effect considered.
2023, 42(2): 181-189.
doi: 10.13433/j.cnki.1003-8728.20200566
Abstract:
Aiming at the improvement of the motion performance of the humanoid wrist, a prototype of the humanoid wrist actuated by shape memory alloy (SMA) is designed, and the position control of the wrist joint was realized by using the antagonistic driving. Based on the relevant theoretical and simulation analysis, the precision of the system model was proved by using the experiments. The effect of the antagonistic driving method on the motion performance of the system was studied by using the experiments of the motion control on the prototype. The results show that the minimum tracking error is [−0.5°, 1°] and the maximum is [−1.5°, 1.5°] for the one-way sinusoidal signals in different frequency tracking experiment with antagonistic driving method. For the sinusoidal signals, the wrist can move continuously in both directions and all of the position errors are less than [−1.5°, 1.5°] when the signal frequency is 1/15 Hz. Comparing with the single-SMA-wire drive method, the antagonistic method is beneficial to improve the position control accuracy and bidirectional deflection ability.
Aiming at the improvement of the motion performance of the humanoid wrist, a prototype of the humanoid wrist actuated by shape memory alloy (SMA) is designed, and the position control of the wrist joint was realized by using the antagonistic driving. Based on the relevant theoretical and simulation analysis, the precision of the system model was proved by using the experiments. The effect of the antagonistic driving method on the motion performance of the system was studied by using the experiments of the motion control on the prototype. The results show that the minimum tracking error is [−0.5°, 1°] and the maximum is [−1.5°, 1.5°] for the one-way sinusoidal signals in different frequency tracking experiment with antagonistic driving method. For the sinusoidal signals, the wrist can move continuously in both directions and all of the position errors are less than [−1.5°, 1.5°] when the signal frequency is 1/15 Hz. Comparing with the single-SMA-wire drive method, the antagonistic method is beneficial to improve the position control accuracy and bidirectional deflection ability.
2023, 42(2): 190-197.
doi: 10.13433/j.cnki.1003-8728.20200608
Abstract:
In view of the phenomena such as the heating of electromagnetic loading device and the instability of electromagnetic force in dynamic test of water-lubricated bearings, the magneto-thermal coupling mechanism of loading device was studied in order to provide the accurate load for bearing performance research. Firstly, the mathematical model of energy loss for electromagnetic loading device was established, and the energy loss was analyzed theoretically. Secondly, the physical model of electromagnetic loading device was constructed, the magneto-thermal coupling simulation analysis was carried out, and the variation rules of magnetic induction intensity, copper loss and iron loss were obtained. Finally, the energy loss test of electromagnetic loading device was carried out. The results show that the main reason of unstable electromagnetic force under dynamic conditions is the energy loss of loading device, and the main energy loss are copper loss and iron loss. Energy loss is related to the shaft speed, the excitation current of electromagnetic loading device and the initial temperature. Under the working condition of excitation current (1 - 3 A), the rotating speed (0 - 1 800 r/min) and the temperature (22 - 50 ℃), the maximum error of electromagnetic force between the test and the simulation results is 4.7%.
In view of the phenomena such as the heating of electromagnetic loading device and the instability of electromagnetic force in dynamic test of water-lubricated bearings, the magneto-thermal coupling mechanism of loading device was studied in order to provide the accurate load for bearing performance research. Firstly, the mathematical model of energy loss for electromagnetic loading device was established, and the energy loss was analyzed theoretically. Secondly, the physical model of electromagnetic loading device was constructed, the magneto-thermal coupling simulation analysis was carried out, and the variation rules of magnetic induction intensity, copper loss and iron loss were obtained. Finally, the energy loss test of electromagnetic loading device was carried out. The results show that the main reason of unstable electromagnetic force under dynamic conditions is the energy loss of loading device, and the main energy loss are copper loss and iron loss. Energy loss is related to the shaft speed, the excitation current of electromagnetic loading device and the initial temperature. Under the working condition of excitation current (1 - 3 A), the rotating speed (0 - 1 800 r/min) and the temperature (22 - 50 ℃), the maximum error of electromagnetic force between the test and the simulation results is 4.7%.
2023, 42(2): 198-202.
doi: 10.13433/j.cnki.1003-8728.20230058
Abstract:
Aiming at the situation that the manipulator is not convenient to grasp directly from the upper part of the object, a flexible grasp control technology of the pneumatic joint of the manipulator is proposed. The conventional grasp mode of the manipulator is analyzed, the geometric constraint relationship between the manipulator and the object is analyzed, and the force condition of the object is carried out when one side is lifted. On this basis, the linear relationship between the curvature of the pneumatic joint and the internal pressure was analyzed, and the flexible grasp control technology of the manipulator to control the internal pressure of the joint was constructed. Through the actual test validation, collect objects curvature change corresponding fingers, the change of the internal pressure, the required to grasp balance under different curvature change of the coefficient of friction, and ground against each other through the fingers, make note of curvature change and the focus moves to the right so as to successfully implement the flexible mechanical arm grasp soft objects, to meet the design goals and objectives.
Aiming at the situation that the manipulator is not convenient to grasp directly from the upper part of the object, a flexible grasp control technology of the pneumatic joint of the manipulator is proposed. The conventional grasp mode of the manipulator is analyzed, the geometric constraint relationship between the manipulator and the object is analyzed, and the force condition of the object is carried out when one side is lifted. On this basis, the linear relationship between the curvature of the pneumatic joint and the internal pressure was analyzed, and the flexible grasp control technology of the manipulator to control the internal pressure of the joint was constructed. Through the actual test validation, collect objects curvature change corresponding fingers, the change of the internal pressure, the required to grasp balance under different curvature change of the coefficient of friction, and ground against each other through the fingers, make note of curvature change and the focus moves to the right so as to successfully implement the flexible mechanical arm grasp soft objects, to meet the design goals and objectives.
2023, 42(2): 203-211.
doi: 10.13433/j.cnki.1003-8728.20200561
Abstract:
To study the rotor system of a large-scale rotating machine, the comprehensive design method is used to design the simulation test device.With the two-level fuzzy evaluation method, the function of the optimal design confirms that of the rotor system through compiling the task book of the test-bed and the overall design scheme,completing the dynamic optimization design. Based on the ANSYS Workbench simulation analysis software, the modal analysis and harmonic response analysis of the four-span rotor system are carried out, and the first six natural frequencies and vibration modes are obtained. The influence of different support stiffness on the critical speed of the rotor system is studied. The Campbell diagram is used to observe the changes of the natural frequency of the rotor system with the increase of speed. The amplitude law of the rotor system under different loads is obtained by harmonic response analysis. With the intelligent optimization design, the parallel misalignment and misalignment experimental devices are designed, being able to accurately control the misalignment. The experimental studiesof the misalignment of deflection angles, i.e. 1° and 2° misalignment, and of the 1 mm and 2 mm misalignments for parallel misalignmentwere carried out. The rotorsystem hasits power frequency and double frequency. With the increase of the deflection angle misalignment, the double frequency component becomes more obvious, and the amplitude increases; the axis track appears in the shape of "8" and concave. When parallel misalignment occurs, the double frequency of the rotor system is the main one and there is an obvious triple frequency.
To study the rotor system of a large-scale rotating machine, the comprehensive design method is used to design the simulation test device.With the two-level fuzzy evaluation method, the function of the optimal design confirms that of the rotor system through compiling the task book of the test-bed and the overall design scheme,completing the dynamic optimization design. Based on the ANSYS Workbench simulation analysis software, the modal analysis and harmonic response analysis of the four-span rotor system are carried out, and the first six natural frequencies and vibration modes are obtained. The influence of different support stiffness on the critical speed of the rotor system is studied. The Campbell diagram is used to observe the changes of the natural frequency of the rotor system with the increase of speed. The amplitude law of the rotor system under different loads is obtained by harmonic response analysis. With the intelligent optimization design, the parallel misalignment and misalignment experimental devices are designed, being able to accurately control the misalignment. The experimental studiesof the misalignment of deflection angles, i.e. 1° and 2° misalignment, and of the 1 mm and 2 mm misalignments for parallel misalignmentwere carried out. The rotorsystem hasits power frequency and double frequency. With the increase of the deflection angle misalignment, the double frequency component becomes more obvious, and the amplitude increases; the axis track appears in the shape of "8" and concave. When parallel misalignment occurs, the double frequency of the rotor system is the main one and there is an obvious triple frequency.
2023, 42(2): 212-217.
doi: 10.13433/j.cnki.1003-8728.20200599
Abstract:
When the lattice structure is printed by the melt deposition technology, there are some problems, such as poor mechanical properties and difficult removal of supporting materials. To solve those problems, the lattice structure is decomposed into several two-dimensional models, printed by FDM, and then reassembled by using the snap fit. Using this split printing, the surface morphology and mechanical properties of four typical lattice structures of BCC, BCC-Z, F2CC and F2CC-Z are deeply explored, and comparing with the traditional integrated printing. It is found that the snap split method can improve the surface quality of the printed objects, save the printing time and printing materials, and improve the compressive performance. The present study provides a way to prepare lattice structures by 3D printing, and provides a reference for selecting the appropriate lattice types.
When the lattice structure is printed by the melt deposition technology, there are some problems, such as poor mechanical properties and difficult removal of supporting materials. To solve those problems, the lattice structure is decomposed into several two-dimensional models, printed by FDM, and then reassembled by using the snap fit. Using this split printing, the surface morphology and mechanical properties of four typical lattice structures of BCC, BCC-Z, F2CC and F2CC-Z are deeply explored, and comparing with the traditional integrated printing. It is found that the snap split method can improve the surface quality of the printed objects, save the printing time and printing materials, and improve the compressive performance. The present study provides a way to prepare lattice structures by 3D printing, and provides a reference for selecting the appropriate lattice types.
2023, 42(2): 218-222.
doi: 10.13433/j.cnki.1003-8728.20200574
Abstract:
The machining of spatial inclined holes is essentially the movement of the electrode of Electrical discharge machining(EDM) along the axis of the hole. For the spatial inclined holes obtained by rotating around three coordinate axes, the electrode axis of the machine tool can be coincided with the axis of the spatial inclined hole by the translation along the three axis and the rotation around the two axis of the 5-axis EDM machine tool. In order to obtain the swinging angle and coordinates of the electrode, the process of obtaining the axis of space oblique hole by coordinate rotation-translation transformation was analyzed. According to the spacial angle and geometric parameters of the spacial inclined hole, the coordinate transformation matrixs of the spacial inclined holes were solved and the vector models of axes of spacial inclined holes were established. The swinging angle and coordinates of the electrode of 5-axis CNC(Computer numerical Control) EDM were obtained to make the axis of electrode on the line of the axis of the spacial inclined hole. According to the geometrical parameters of the spacial inclined hole, a software was developed to calculate the swinging angle and electrode coordinates.
The machining of spatial inclined holes is essentially the movement of the electrode of Electrical discharge machining(EDM) along the axis of the hole. For the spatial inclined holes obtained by rotating around three coordinate axes, the electrode axis of the machine tool can be coincided with the axis of the spatial inclined hole by the translation along the three axis and the rotation around the two axis of the 5-axis EDM machine tool. In order to obtain the swinging angle and coordinates of the electrode, the process of obtaining the axis of space oblique hole by coordinate rotation-translation transformation was analyzed. According to the spacial angle and geometric parameters of the spacial inclined hole, the coordinate transformation matrixs of the spacial inclined holes were solved and the vector models of axes of spacial inclined holes were established. The swinging angle and coordinates of the electrode of 5-axis CNC(Computer numerical Control) EDM were obtained to make the axis of electrode on the line of the axis of the spacial inclined hole. According to the geometrical parameters of the spacial inclined hole, a software was developed to calculate the swinging angle and electrode coordinates.
2023, 42(2): 223-230.
doi: 10.13433/j.cnki.1003-8728.20200602
Abstract:
In order to solve the problem of structural dimension out of tolerance caused by the milling deformation in the milling of spacecraft X-shape integral panel, a method was proposed to optimize the milling process with finite element simulation to estimate the machining deformation degree of parts. In this paper, the force state of the panel in the milling was studied, and a method to obtain the milling force in all directions with the milling trajectory was given, the milling force finite element simulation was used to estimate the milling deformation degree of integral panel. At the same time, according to the optimized process plan, the separate cavity vacuum adsorption process equipment was designed. The limitation of this method to control the milling deformation was verified by an example.
In order to solve the problem of structural dimension out of tolerance caused by the milling deformation in the milling of spacecraft X-shape integral panel, a method was proposed to optimize the milling process with finite element simulation to estimate the machining deformation degree of parts. In this paper, the force state of the panel in the milling was studied, and a method to obtain the milling force in all directions with the milling trajectory was given, the milling force finite element simulation was used to estimate the milling deformation degree of integral panel. At the same time, according to the optimized process plan, the separate cavity vacuum adsorption process equipment was designed. The limitation of this method to control the milling deformation was verified by an example.
2023, 42(2): 231-240.
doi: 10.13433/j.cnki.1003-8728.20200572
Abstract:
In order to solve the short life of the conventional screw drill and the difficulty of machining small-sized stator of the screw drill with equal wall thickness, this paper uses hydraulic pressure forming technology to manufacture the small-sized equal-wall spiral tubes. Based on the 304 stainless steel tensile experiment, a finite element model for spiral tube with equal wall thickness formed by hydraulic pressure was established. The numerical simulation method is used to study the influence of the pipe outer diameter, wall thickness, hydraulic pressure, hydraulic pressure loading path, pressing speed and friction coefficient on the quality of the spiral pipe. The results show that when the outer diameter of the pipe is 51.8 mm and the wall thickness is 5.3 mm, the quality of the spiral pipe is better, the maximum hydraulic pressure is 650 MPa, the hydraulic pressure loading path is path 5, and the extrusion speed of the die is 0.429 m/s. When the friction coefficient does not exceed 0.125, the spiral tube quality is better, the lead error is approximately 0, the wall thickness error is less than 8%, the average thickness is 5 mm, and the wall thickness error in the middle of the spiral tube is less than 3%. The result can provide the reference for forming the stainless steel spiral pipe with the small size and equal wall thickness.
In order to solve the short life of the conventional screw drill and the difficulty of machining small-sized stator of the screw drill with equal wall thickness, this paper uses hydraulic pressure forming technology to manufacture the small-sized equal-wall spiral tubes. Based on the 304 stainless steel tensile experiment, a finite element model for spiral tube with equal wall thickness formed by hydraulic pressure was established. The numerical simulation method is used to study the influence of the pipe outer diameter, wall thickness, hydraulic pressure, hydraulic pressure loading path, pressing speed and friction coefficient on the quality of the spiral pipe. The results show that when the outer diameter of the pipe is 51.8 mm and the wall thickness is 5.3 mm, the quality of the spiral pipe is better, the maximum hydraulic pressure is 650 MPa, the hydraulic pressure loading path is path 5, and the extrusion speed of the die is 0.429 m/s. When the friction coefficient does not exceed 0.125, the spiral tube quality is better, the lead error is approximately 0, the wall thickness error is less than 8%, the average thickness is 5 mm, and the wall thickness error in the middle of the spiral tube is less than 3%. The result can provide the reference for forming the stainless steel spiral pipe with the small size and equal wall thickness.
2023, 42(2): 241-245.
doi: 10.13433/j.cnki.1003-8728.20230106
Abstract:
Aluminium alloy forgings will produce residual stress in the process of forging, cutting, heat treatment and other processes. When the internal residual stress of metal is in balance, the performance of metal structure is higher. When the internal residual stress of metal is unbalanced, the internal stress will be released to produce deformation phenomenon, and the performance of metal structure will be reduced. Taking the wrought aluminiumalloy forgings as the research object, this paper analyses the relationship between residual stress and deformation, and put forward preventive measures and methods to eliminate deformation.
Aluminium alloy forgings will produce residual stress in the process of forging, cutting, heat treatment and other processes. When the internal residual stress of metal is in balance, the performance of metal structure is higher. When the internal residual stress of metal is unbalanced, the internal stress will be released to produce deformation phenomenon, and the performance of metal structure will be reduced. Taking the wrought aluminiumalloy forgings as the research object, this paper analyses the relationship between residual stress and deformation, and put forward preventive measures and methods to eliminate deformation.
2023, 42(2): 246-251.
doi: 10.13433/j.cnki.1003-8728.20200595
Abstract:
In order to solve the problem that the concrete piston of the concrete pump truck could not be replaced in time,an improved gray wolf algorithm was proposed to optimized the remaining life prediction method of the Least Square Support Vector Regression (LSSVR).The new method DE-GWO-LSSVR uses the difference evolution algorithm to optimize the original gray wolf algorithm which solves the problem that it is easy to fall into the local optimal solution, improves the convergence speed, and then uses the optimized algorithm to optimize the two parameters of the least square support vector regression to establish the remaining life prediction model. Based on real concrete piston life monitoring data, three evaluation indicators are used to compare the prediction effects of the three models of LSSVR, GWO-LSSVR, and DE-GWO-LSSVR, and compare them with the results of related studies. Experiments show that the DE-GWO-LSSVR model has the highest prediction accuracy, which can provide guidance for the predictive replacement of concrete pistons and the fault diagnosis of mechanical parts.
In order to solve the problem that the concrete piston of the concrete pump truck could not be replaced in time,an improved gray wolf algorithm was proposed to optimized the remaining life prediction method of the Least Square Support Vector Regression (LSSVR).The new method DE-GWO-LSSVR uses the difference evolution algorithm to optimize the original gray wolf algorithm which solves the problem that it is easy to fall into the local optimal solution, improves the convergence speed, and then uses the optimized algorithm to optimize the two parameters of the least square support vector regression to establish the remaining life prediction model. Based on real concrete piston life monitoring data, three evaluation indicators are used to compare the prediction effects of the three models of LSSVR, GWO-LSSVR, and DE-GWO-LSSVR, and compare them with the results of related studies. Experiments show that the DE-GWO-LSSVR model has the highest prediction accuracy, which can provide guidance for the predictive replacement of concrete pistons and the fault diagnosis of mechanical parts.
2023, 42(2): 252-259.
doi: 10.13433/j.cnki.1003-8728.20230038
Abstract:
A full-view weak barrier coverage geometric model was proposed in this paper, with the aim of solving the problem of intrusion detection based on full-view weak barrier coverage in wireless visual sensor networks (WVSN), and the full-view weak barrier coverage problem can be discretized through the grid method. Besides, the problem can be expressed as an integer programming problem which is proven being a NP-Hard. Subsequently, a heuristic algorithm of grid thickness priority WVSN full-view weak barrier coverage (GTPFWBC) was proposed. To verify the effectiveness of the algorithm, extensive simulation experiments were conducted already. The experimental results shown that GTPFWBC is able to solve the full-view weak barrier coverage problem of WVSN effectively. The success rate of GTPFWBC in constructing full-view barriers is obviously better than W-Graproj, SP and DP1 algorithms. Compared with W-Graproj and SP, the average number of nodes for constructing WVSN barriers is about 30.6% and 59.4% less, respectively. In addition, the time complexity of GTPFWBC is much smaller than that of W-GraProj, SP and DP1. Therefore, the conclusion that the effectiveness of GTPFWBC algorithm is much better in WVSN with limited energy and high real-time requirements can be drawn.
A full-view weak barrier coverage geometric model was proposed in this paper, with the aim of solving the problem of intrusion detection based on full-view weak barrier coverage in wireless visual sensor networks (WVSN), and the full-view weak barrier coverage problem can be discretized through the grid method. Besides, the problem can be expressed as an integer programming problem which is proven being a NP-Hard. Subsequently, a heuristic algorithm of grid thickness priority WVSN full-view weak barrier coverage (GTPFWBC) was proposed. To verify the effectiveness of the algorithm, extensive simulation experiments were conducted already. The experimental results shown that GTPFWBC is able to solve the full-view weak barrier coverage problem of WVSN effectively. The success rate of GTPFWBC in constructing full-view barriers is obviously better than W-Graproj, SP and DP1 algorithms. Compared with W-Graproj and SP, the average number of nodes for constructing WVSN barriers is about 30.6% and 59.4% less, respectively. In addition, the time complexity of GTPFWBC is much smaller than that of W-GraProj, SP and DP1. Therefore, the conclusion that the effectiveness of GTPFWBC algorithm is much better in WVSN with limited energy and high real-time requirements can be drawn.
2023, 42(2): 260-266.
doi: 10.13433/j.cnki.1003-8728.20200580
Abstract:
Aiming at the problems of poor accuracy and poor real-time estimation of traditional sideslip angle, a new sideslip angle estimation method based on strong tracking Kalman filter and unscented Kalman filter fusion estimation is proposed for four-wheel independent drive electric vehicle. Since the vehicle dynamics characteristics are roughly linear when the lateral acceleration is small, the strong tracking Kalman filter is used to quickly estimate the sideslip angle at this time. When the lateral acceleration of the vehicle is larger, the vehicle dynamics characteristics tend to be nonlinear, the sideslip angle can be accurately estimated by unscented Kalman filter. Finally, the data of the two estimation methods are fused to realize the estimation of the sideslip angle under different vehicle speeds and different working conditions. The Simulink-Carsim joint simulation platform is built to verify the proposed method. The results show that the method has good real-time tracking effect and robustness while ensuring the estimation accuracy.
Aiming at the problems of poor accuracy and poor real-time estimation of traditional sideslip angle, a new sideslip angle estimation method based on strong tracking Kalman filter and unscented Kalman filter fusion estimation is proposed for four-wheel independent drive electric vehicle. Since the vehicle dynamics characteristics are roughly linear when the lateral acceleration is small, the strong tracking Kalman filter is used to quickly estimate the sideslip angle at this time. When the lateral acceleration of the vehicle is larger, the vehicle dynamics characteristics tend to be nonlinear, the sideslip angle can be accurately estimated by unscented Kalman filter. Finally, the data of the two estimation methods are fused to realize the estimation of the sideslip angle under different vehicle speeds and different working conditions. The Simulink-Carsim joint simulation platform is built to verify the proposed method. The results show that the method has good real-time tracking effect and robustness while ensuring the estimation accuracy.
2023, 42(2): 267-281.
doi: 10.13433/j.cnki.1003-8728.20230074
Abstract:
With its excellent physical and chemical properties and mechanical properties, rigid polyurethane foam materials are widely used in many fields such as national production and defence industry, and have an irreplaceable and important role to play. Meanwhile, with the progress of material forming technology, some new rigid polyurethane composites with enhanced properties have been developed. This paper reviews the recent research progress on the raw material system, moulding process and flame retardant polyurethane foam and material reinforcement methods of rigid polyurethane foam materials, and analyzes in detail the reinforcement mechanism and influence law of isocyanate, polyol and various fibers and particle reinforcement materials on the performance of rigid polyurethane foam. Finally, the future research and development directions of rigid polyurethane foams are presented.
With its excellent physical and chemical properties and mechanical properties, rigid polyurethane foam materials are widely used in many fields such as national production and defence industry, and have an irreplaceable and important role to play. Meanwhile, with the progress of material forming technology, some new rigid polyurethane composites with enhanced properties have been developed. This paper reviews the recent research progress on the raw material system, moulding process and flame retardant polyurethane foam and material reinforcement methods of rigid polyurethane foam materials, and analyzes in detail the reinforcement mechanism and influence law of isocyanate, polyol and various fibers and particle reinforcement materials on the performance of rigid polyurethane foam. Finally, the future research and development directions of rigid polyurethane foams are presented.
2023, 42(2): 282-286.
doi: 10.13433/j.cnki.1003-8728.20200559
Abstract:
The self-piercing riveted joint of AA5052-AA5052 (MJ) and adhesive-riveting composite joint of AA5052-AA5052 (ZM) were studied. Using 0.02 mol/L NaHSO3 solution as corrosion condition, the failure load, failure mode and morphology were analyzed by cyclic wet-dry immersion corrosion test, statics test and energy dispersive X-ray. The static properties of the two sets of joints were compared. The results show that the adhesive has a promoting effect on the static strength of the joint. Due to the influence of the corrosion products, the static strength of the joint decreases first and then increases. The adhesive reduces the energy absorption value of the joint, and the corrosion time has no great influence on the capacity of the joint to buffer and absorb vibration. The failure mode of MJ is T type failure, and ZM presents T type failure and C type failure, thus failure mode of the joint is also affected by the adhesive. The surface composition of sheet and rivet also changed obviously after corrosion.
The self-piercing riveted joint of AA5052-AA5052 (MJ) and adhesive-riveting composite joint of AA5052-AA5052 (ZM) were studied. Using 0.02 mol/L NaHSO3 solution as corrosion condition, the failure load, failure mode and morphology were analyzed by cyclic wet-dry immersion corrosion test, statics test and energy dispersive X-ray. The static properties of the two sets of joints were compared. The results show that the adhesive has a promoting effect on the static strength of the joint. Due to the influence of the corrosion products, the static strength of the joint decreases first and then increases. The adhesive reduces the energy absorption value of the joint, and the corrosion time has no great influence on the capacity of the joint to buffer and absorb vibration. The failure mode of MJ is T type failure, and ZM presents T type failure and C type failure, thus failure mode of the joint is also affected by the adhesive. The surface composition of sheet and rivet also changed obviously after corrosion.
2023, 42(2): 287-293.
doi: 10.13433/j.cnki.1003-8728.20200606
Abstract:
Ultrasonic fatigue technology offers an alternative and effective method for very high cycle fatigue testing. However, there is no stress calibration method for ultrasonic fatigue testing to assure the testing reliability and accuracy.Ultrasonic specimen design and stress distribution formula of different shapes are firstly introduced in this work. Then, high speed strain gauge and high speed camera based digital image correlation are utilized to measure the dynamic strain of ultrasonic fatigue specimen. The consistency of the measured results and the theoretical values confirms the feasibility of strain calibration for the ultrasonic fatigue specimen. As the linearity of the ultrasonic testing system, the stress can be calibrated according to the measured strain and the dynamic elastic modulus to ensure the reliability and accuracy of ultrasonic fatigue test results.
Ultrasonic fatigue technology offers an alternative and effective method for very high cycle fatigue testing. However, there is no stress calibration method for ultrasonic fatigue testing to assure the testing reliability and accuracy.Ultrasonic specimen design and stress distribution formula of different shapes are firstly introduced in this work. Then, high speed strain gauge and high speed camera based digital image correlation are utilized to measure the dynamic strain of ultrasonic fatigue specimen. The consistency of the measured results and the theoretical values confirms the feasibility of strain calibration for the ultrasonic fatigue specimen. As the linearity of the ultrasonic testing system, the stress can be calibrated according to the measured strain and the dynamic elastic modulus to ensure the reliability and accuracy of ultrasonic fatigue test results.
2023, 42(2): 294-300.
doi: 10.13433/j.cnki.1003-8728.20200570
Abstract:
In this work, Ni-based spray welding coatings reinforced with various content of spherical cast tungsten carbide (CTC-S) and angular cast tungsten carbide (CTC-A) particles are fabricated with the oxy-acetylene welding. The erosion behavior of WC-Ni hardfacing used for steel body PDC drill bit are investigated inexperiments. Results show that as CTC-S content decreases, the microhardness of coatings decrease while their fracture toughness increase, and the porosity increases firstly and becomes stable. The erosion resistance decreases firstly and increases with the decreasing of CTC-S content, and the corrosion resistance is the most important factor affecting the erosion resistance of the hardfacing coating. When the content of CTC-S is 30%, the corrosion resistance of the sample is the worst, and the corrosion-erosion interaction is the strongest, leading to serious erosion wear of the sample. It is recommended that the content of CTC-S should not be less than 40% to maintain the high hardness and erosion resistance of the coating.
In this work, Ni-based spray welding coatings reinforced with various content of spherical cast tungsten carbide (CTC-S) and angular cast tungsten carbide (CTC-A) particles are fabricated with the oxy-acetylene welding. The erosion behavior of WC-Ni hardfacing used for steel body PDC drill bit are investigated inexperiments. Results show that as CTC-S content decreases, the microhardness of coatings decrease while their fracture toughness increase, and the porosity increases firstly and becomes stable. The erosion resistance decreases firstly and increases with the decreasing of CTC-S content, and the corrosion resistance is the most important factor affecting the erosion resistance of the hardfacing coating. When the content of CTC-S is 30%, the corrosion resistance of the sample is the worst, and the corrosion-erosion interaction is the strongest, leading to serious erosion wear of the sample. It is recommended that the content of CTC-S should not be less than 40% to maintain the high hardness and erosion resistance of the coating.
2023, 42(2): 301-308.
doi: 10.13433/j.cnki.1003-8728.20200560
Abstract:
Multiple UAVs can achieve overall combat effectiveness improvement through coordination, capability complementation and action coordination. Therefore, it is of great significance to study the maintenance strategy of UAV clusters in the battlefield environment. For the deployment of UAVs that perform multiple missions successively, maintenance and repairs between missions are an important means to improve the stability of combat operations. Effectively repairing the malfunctioning module and quickly recovering the combat effectiveness of the UAV cluster have a decisive influence on the cluster combat strategy of performing multiple consecutive missions. This study establishes a basic maintenance model based on distinguished assumptions of different maintenance scales, arrival matter and information availability. Based on the special requirements and constraints of the combat environment, a "one-stop" maintenance strategy for rapid repair in a large number of battlefield environments is proposed. With the goal of minimizing maintenance time and maximizing the recovery of combat effectiveness, the optimization problem is solved to provide guarantee for the execution of continuous tasks.
Multiple UAVs can achieve overall combat effectiveness improvement through coordination, capability complementation and action coordination. Therefore, it is of great significance to study the maintenance strategy of UAV clusters in the battlefield environment. For the deployment of UAVs that perform multiple missions successively, maintenance and repairs between missions are an important means to improve the stability of combat operations. Effectively repairing the malfunctioning module and quickly recovering the combat effectiveness of the UAV cluster have a decisive influence on the cluster combat strategy of performing multiple consecutive missions. This study establishes a basic maintenance model based on distinguished assumptions of different maintenance scales, arrival matter and information availability. Based on the special requirements and constraints of the combat environment, a "one-stop" maintenance strategy for rapid repair in a large number of battlefield environments is proposed. With the goal of minimizing maintenance time and maximizing the recovery of combat effectiveness, the optimization problem is solved to provide guarantee for the execution of continuous tasks.
2023, 42(2): 309-320.
doi: 10.13433/j.cnki.1003-8728.20200605
Abstract:
Taking the NACA 0012 airfoil as research object,the flight condition selects 0.176 Mach number of incoming flow. Firstly, the influences of the different factors on the aerodynamic performance of the airfoil have been investigated by the numerical simulation, such as the downward bending angle and deflection position of the leading and trailing edgefor the airfoil and so on. Secondly, the prediction model between the object variable lift-drag ratio and the above four design variables is established by the neural network. Then under consideration of the optimization precision and the computation cost of neural network training database, an iterative optimization strategy is present, which is coupled with the neural network and optimization process. Furthermore, the optimal variable camber airfoil configuration is obtained based on the optimization strategy. Compared with the original airfoil, the optimized one increases the lift-drag ratioby about the 22%, and the aerodynamic characteristics of airfoil have been greatly improved. Moreover, by far field noise analysis, it is found that the optimized airfoil has better acoustic performance, and the tonal noise of around 1 000 Hz can be reduced by up to 12 dB.
Taking the NACA 0012 airfoil as research object,the flight condition selects 0.176 Mach number of incoming flow. Firstly, the influences of the different factors on the aerodynamic performance of the airfoil have been investigated by the numerical simulation, such as the downward bending angle and deflection position of the leading and trailing edgefor the airfoil and so on. Secondly, the prediction model between the object variable lift-drag ratio and the above four design variables is established by the neural network. Then under consideration of the optimization precision and the computation cost of neural network training database, an iterative optimization strategy is present, which is coupled with the neural network and optimization process. Furthermore, the optimal variable camber airfoil configuration is obtained based on the optimization strategy. Compared with the original airfoil, the optimized one increases the lift-drag ratioby about the 22%, and the aerodynamic characteristics of airfoil have been greatly improved. Moreover, by far field noise analysis, it is found that the optimized airfoil has better acoustic performance, and the tonal noise of around 1 000 Hz can be reduced by up to 12 dB.
2023, 42(2): 321-328.
doi: 10.13433/j.cnki.1003-8728.20200584
Abstract:
In order to explore the noise reduction effect of wavy airfoil, the hybrid method of large eddy simulation (LES) and boundary element method (BEM) was used to study three different wavy airfoils. The feasibility of the simulation model was verified by experiment. Furthermore, the influence of three different wavy airfoils( wavy surface airfoil-A, wavy leading edge airfoil-B and wavy leading edge + wavy surfaceairfoil-C) on the cylinder-airfoil interaction noise is analyzed. The research results show that all the three models can reduce the turbulence-airfoil interference noise to a certain extent, and the Wavy airfoil-C model has the best noise reduction effect, the noise reduction frequency range is the widest, and the total sound pressure level noise reduction amount in the vertical flow direction up to 6.7 dB; Wavy airfoil-C model can effectively reduce airfoil surface pressure pulsation, turbulence intensity on each section, fluctuation of lift and drag coefficient, power spectral density, but also use its wavy leading edge structure to effectively reduce the leading edge The area of the main sound source area, and can use the diversion effect of the wavy surface structure to reduce the sound pressure amplitude of the trailing edge of the airfoil.
In order to explore the noise reduction effect of wavy airfoil, the hybrid method of large eddy simulation (LES) and boundary element method (BEM) was used to study three different wavy airfoils. The feasibility of the simulation model was verified by experiment. Furthermore, the influence of three different wavy airfoils( wavy surface airfoil-A, wavy leading edge airfoil-B and wavy leading edge + wavy surfaceairfoil-C) on the cylinder-airfoil interaction noise is analyzed. The research results show that all the three models can reduce the turbulence-airfoil interference noise to a certain extent, and the Wavy airfoil-C model has the best noise reduction effect, the noise reduction frequency range is the widest, and the total sound pressure level noise reduction amount in the vertical flow direction up to 6.7 dB; Wavy airfoil-C model can effectively reduce airfoil surface pressure pulsation, turbulence intensity on each section, fluctuation of lift and drag coefficient, power spectral density, but also use its wavy leading edge structure to effectively reduce the leading edge The area of the main sound source area, and can use the diversion effect of the wavy surface structure to reduce the sound pressure amplitude of the trailing edge of the airfoil.
