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RSS2022 Vol. 41, No. 6
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2022, 41(6): 821-826.
doi: 10.13433/j.cnki.1003-8728.20200396
PDF 1903KB
Abstract:
The friction characteristics between the tool and the chip will affect the cutting force, cutting heat and tool wear in the milling. Aiming at the above mentioned, an empirical model between the normal stress and the relative temperature to describe the tool-chip friction coefficient is established. The HT-1000 multifunctional ball-disk friction and wear tester was used to simulate the friction process among the cemented carbide tools and Ti6Al4V parts, and the friction coefficient model by considering contact stress and cutting temperature was established and verified through the testing data. With the present friction coefficient model, the model for milling force is constructed based on the oblique cutting theory, which can be further verified via the milling experiment of titanium alloy.
The friction characteristics between the tool and the chip will affect the cutting force, cutting heat and tool wear in the milling. Aiming at the above mentioned, an empirical model between the normal stress and the relative temperature to describe the tool-chip friction coefficient is established. The HT-1000 multifunctional ball-disk friction and wear tester was used to simulate the friction process among the cemented carbide tools and Ti6Al4V parts, and the friction coefficient model by considering contact stress and cutting temperature was established and verified through the testing data. With the present friction coefficient model, the model for milling force is constructed based on the oblique cutting theory, which can be further verified via the milling experiment of titanium alloy.
2022, 41(6): 827-832.
doi: 10.13433/j.cnki.1003-8728.20200422
Abstract:
Based on the discrete element method and EDEM, the model of drilling fluid shaker was simplified to explore the influence of particle bonding phenomenon on particle velocity and movement trajectory of translational elliptical vibration type drilling fluid shaker under different vibration parameters, and the screening efficiency of different particles was compared with it. The results show that the particle bonding effect affects the particle screening efficiency by affecting the particle velocity and motion trajectory. The larger the binding effect of particles, the more the number of particles forming particle clusters, the more times of parabolic movement of particles, the greater the decrease of the overall velocity of particles, and the smaller the screening efficiency of the sieve mesh to particles. The results can be used as a reference for increasing the screening efficiency of particles by making full use of the effect of particle bonding on various particles under different working conditions.
Based on the discrete element method and EDEM, the model of drilling fluid shaker was simplified to explore the influence of particle bonding phenomenon on particle velocity and movement trajectory of translational elliptical vibration type drilling fluid shaker under different vibration parameters, and the screening efficiency of different particles was compared with it. The results show that the particle bonding effect affects the particle screening efficiency by affecting the particle velocity and motion trajectory. The larger the binding effect of particles, the more the number of particles forming particle clusters, the more times of parabolic movement of particles, the greater the decrease of the overall velocity of particles, and the smaller the screening efficiency of the sieve mesh to particles. The results can be used as a reference for increasing the screening efficiency of particles by making full use of the effect of particle bonding on various particles under different working conditions.
2022, 41(6): 833-839.
doi: 10.13433/j.cnki.1003-8728.20200390
Abstract:
In order to better understand the flow field characteristics of an underwater vehicle and the change law of radiated noise, the SST k-ω model and fluid simulation software are used to extract the surface pressure of the underwater vehicle under three flow velocity conditions. The paper summarizes the change law of drag coefficient over time, derives the change of pressure at the nose of an aircraft and simulates the velocity distribution of the aircraft on its symmetrical plane. The wall pressure pulse is used as a dipole sound source, and the direct boundary element method (BEM) is used to simulate and calculate the sound pressure cloud diagram and the distribution of the sound power level of a field point. A detector in the axial direction is installed to discuss the axial variation characteristics of shell radiation noise. The research results show that the higher the incoming flow velocity, the greater the resistance and pressure experienced by the aircraft, and the larger the radiated noise of the aircraft structure; the closer to the aircraft the point in the sound field, the greater the sound pressure. In addition, the sound pressure attenuates faster in the near-field region, and the variation law of the aircraft radiated noise obtained by simulation is accurate and feasible.
In order to better understand the flow field characteristics of an underwater vehicle and the change law of radiated noise, the SST k-ω model and fluid simulation software are used to extract the surface pressure of the underwater vehicle under three flow velocity conditions. The paper summarizes the change law of drag coefficient over time, derives the change of pressure at the nose of an aircraft and simulates the velocity distribution of the aircraft on its symmetrical plane. The wall pressure pulse is used as a dipole sound source, and the direct boundary element method (BEM) is used to simulate and calculate the sound pressure cloud diagram and the distribution of the sound power level of a field point. A detector in the axial direction is installed to discuss the axial variation characteristics of shell radiation noise. The research results show that the higher the incoming flow velocity, the greater the resistance and pressure experienced by the aircraft, and the larger the radiated noise of the aircraft structure; the closer to the aircraft the point in the sound field, the greater the sound pressure. In addition, the sound pressure attenuates faster in the near-field region, and the variation law of the aircraft radiated noise obtained by simulation is accurate and feasible.
2022, 41(6): 840-848.
doi: 10.13433/j.cnki.1003-8728.20200419
Abstract:
In order to find out and solve the damage and corrosion of the JJ225 / 45-K derrick leg in advance, the structure of a derrick climbing robot is designed based on the adsorption principle of permanent magnet and derrick leg. Firstly, the climbing foot and climbing gait of the derrick climbing robot are analyzed. The analysis finds that its obstacle climbing gait and space overturning gait are prone to overturn. The Maxwell software simulated the magnetic force of the robot's adsorption foot permanent magnet. The simulation results show that the size of the primary permanent magnet did not meet the requirements. Therefore, the size of the permanent magnet on the adsorption foot was adjusted. Finally, the anti-overturning analysis of the climbing robot was carried out with the ADAMS software to verify the safety of the climbing robot after adjusting the size of the permanent magnet, thus revealing that the size of the permanent magnet adsorption foot can safely climb on the derrick without overturning.
In order to find out and solve the damage and corrosion of the JJ225 / 45-K derrick leg in advance, the structure of a derrick climbing robot is designed based on the adsorption principle of permanent magnet and derrick leg. Firstly, the climbing foot and climbing gait of the derrick climbing robot are analyzed. The analysis finds that its obstacle climbing gait and space overturning gait are prone to overturn. The Maxwell software simulated the magnetic force of the robot's adsorption foot permanent magnet. The simulation results show that the size of the primary permanent magnet did not meet the requirements. Therefore, the size of the permanent magnet on the adsorption foot was adjusted. Finally, the anti-overturning analysis of the climbing robot was carried out with the ADAMS software to verify the safety of the climbing robot after adjusting the size of the permanent magnet, thus revealing that the size of the permanent magnet adsorption foot can safely climb on the derrick without overturning.
2022, 41(6): 849-856.
doi: 10.13433/j.cnki.1003-8728.20200423
Abstract:
Aiming at the problem that under a certain load, due to the pressure and flow pulsation of the hydraulic system of the hydraulic mechanical continuously variable transmission (HMCVT) wet clutch, and the winner of the driven shaft for a long time to produce a large speed difference and being in the state of sliding friction, these lead to the wet clutch change is not ideal. By analyzing the fault formation mechanism of wet clutch hydraulic system, modeled hydraulic system failure using AMESim structures, and simulating the fault injection and extracting the time domain feature, the quantum particle swarm optimization (QPSO) algorithm of BP neural network weights and threshold of wet clutch hydraulic system fault diagnosis are put forward to improve the diagnostic efficiency and diagnostic accuracy of the system, and finally validating the accuracy of the algorithm though the bench experiment. The results show that the QPSO algorithm has higher fault recognition rate, higher convergence accuracy and higher convergence speed. The research results provide theoretical reference and engineering development ideas for the design of tractor HMCVT fault self-diagnosis system.
Aiming at the problem that under a certain load, due to the pressure and flow pulsation of the hydraulic system of the hydraulic mechanical continuously variable transmission (HMCVT) wet clutch, and the winner of the driven shaft for a long time to produce a large speed difference and being in the state of sliding friction, these lead to the wet clutch change is not ideal. By analyzing the fault formation mechanism of wet clutch hydraulic system, modeled hydraulic system failure using AMESim structures, and simulating the fault injection and extracting the time domain feature, the quantum particle swarm optimization (QPSO) algorithm of BP neural network weights and threshold of wet clutch hydraulic system fault diagnosis are put forward to improve the diagnostic efficiency and diagnostic accuracy of the system, and finally validating the accuracy of the algorithm though the bench experiment. The results show that the QPSO algorithm has higher fault recognition rate, higher convergence accuracy and higher convergence speed. The research results provide theoretical reference and engineering development ideas for the design of tractor HMCVT fault self-diagnosis system.
2022, 41(6): 857-861.
doi: 10.13433/j.cnki.1003-8728.20200381
Abstract:
In order to study the transverse vibration and noise of the V-ribbed belt, the mechanism of vibration and noise of the V-ribbed belt transmission is analyzed. Based on the string model, the differential equation of the transverse vibration of the belt is established, and the natural frequency of the transverse vibration of the belt is solved. For the two-wheel 6PK V-ribbed belt drive system, the vibration boundary conditions are solved by harmonic response analysis, and the frequency response curves and sound pressure distribution nephogram of key field points are solved by acoustic boundary element method. Based on the principle of acoustic array measurement, the transverse vibration and noise of two-wheel multi wedge belt drive system is tested. The simulation and experimental results show that when the excitation frequency caused by elastic sliding is coupled with the natural frequency of the span region, the sharp resonance noise will occur in the middle of the span region.
In order to study the transverse vibration and noise of the V-ribbed belt, the mechanism of vibration and noise of the V-ribbed belt transmission is analyzed. Based on the string model, the differential equation of the transverse vibration of the belt is established, and the natural frequency of the transverse vibration of the belt is solved. For the two-wheel 6PK V-ribbed belt drive system, the vibration boundary conditions are solved by harmonic response analysis, and the frequency response curves and sound pressure distribution nephogram of key field points are solved by acoustic boundary element method. Based on the principle of acoustic array measurement, the transverse vibration and noise of two-wheel multi wedge belt drive system is tested. The simulation and experimental results show that when the excitation frequency caused by elastic sliding is coupled with the natural frequency of the span region, the sharp resonance noise will occur in the middle of the span region.
2022, 41(6): 862-868.
doi: 10.13433/j.cnki.1003-8728.20200549
Abstract:
Magnetically controlled capsule robots are mainly used in the diagnosis and treatment of human intestines. According to the permanent magnet method, a set of fluid flow field measurement system is designed and manufactured when the capsule robot is precessing in the pipe. The CFD (Computational fluid dynamics) method and the PIV (particle image velocimetry) technology are used to measure the fluid vorticity around the robot. The change trend and size of the numerical calculation and the experimental measurement results are basically the same. Furthermore, the uniform design method is used to numerically calculate the influences of pipe diameter, robotic translational speed, robotic rotational speed, and fluid dynamic viscosity on the stable operation of the capsule robot (that is, the fluid turbulent intensity around the robot is taken as an important index). The first-order regression model of fluid turbulent intensity around the capsule robot is established. The results show that the various parameters of the capsule robot system have different effects on the fluid turbulent intensity around the robot. Among them, the rank of influence is: fluid dynamic viscosity > robotic translational speed ≈ robotic rotational speed > pipe diameter. Under the best stable operation of the robot, the combination of various parameters is: the pipe diameter is 16 mm, the robotic translational speed is 0.02 m/s, the robotic rotational speed is 90 r/min, and the fluid dynamic viscosity is 0.005 Pa·s.
Magnetically controlled capsule robots are mainly used in the diagnosis and treatment of human intestines. According to the permanent magnet method, a set of fluid flow field measurement system is designed and manufactured when the capsule robot is precessing in the pipe. The CFD (Computational fluid dynamics) method and the PIV (particle image velocimetry) technology are used to measure the fluid vorticity around the robot. The change trend and size of the numerical calculation and the experimental measurement results are basically the same. Furthermore, the uniform design method is used to numerically calculate the influences of pipe diameter, robotic translational speed, robotic rotational speed, and fluid dynamic viscosity on the stable operation of the capsule robot (that is, the fluid turbulent intensity around the robot is taken as an important index). The first-order regression model of fluid turbulent intensity around the capsule robot is established. The results show that the various parameters of the capsule robot system have different effects on the fluid turbulent intensity around the robot. Among them, the rank of influence is: fluid dynamic viscosity > robotic translational speed ≈ robotic rotational speed > pipe diameter. Under the best stable operation of the robot, the combination of various parameters is: the pipe diameter is 16 mm, the robotic translational speed is 0.02 m/s, the robotic rotational speed is 90 r/min, and the fluid dynamic viscosity is 0.005 Pa·s.
2022, 41(6): 869-876.
doi: 10.13433/j.cnki.1003-8728.20220102
Abstract:
Considering the complexity of rolling bearing vibration signals, it is difficult to obtain ideal fault diagnosis results only using single fault feature, a novel multi-feature fusion intelligent fault diagnosis method based on multi-kernel multi-class relevance vector machine was proposed. According to the contribution of fault features, different fault features are mapped to high dimensional feature space and fused to multiple feature spaces with weighted summation in this method. It can overcome the curse of dimensionality if different features are integrated directly, because the effective properties of different feature vector are fully utilized. Additionally, corresponding kernel parameters of different fault features are selected adaptively by quantum genetic algorithm, and the fault identification accuracy can be further improved. Compared with other methods, the experiment of rolling bearing fault diagnosis shows that the proposed method can fuse various fault features of rolling bearing effectively and achieve higher fault diagnosis accuracy.
Considering the complexity of rolling bearing vibration signals, it is difficult to obtain ideal fault diagnosis results only using single fault feature, a novel multi-feature fusion intelligent fault diagnosis method based on multi-kernel multi-class relevance vector machine was proposed. According to the contribution of fault features, different fault features are mapped to high dimensional feature space and fused to multiple feature spaces with weighted summation in this method. It can overcome the curse of dimensionality if different features are integrated directly, because the effective properties of different feature vector are fully utilized. Additionally, corresponding kernel parameters of different fault features are selected adaptively by quantum genetic algorithm, and the fault identification accuracy can be further improved. Compared with other methods, the experiment of rolling bearing fault diagnosis shows that the proposed method can fuse various fault features of rolling bearing effectively and achieve higher fault diagnosis accuracy.
2022, 41(6): 877-884.
doi: 10.13433/j.cnki.1003-8728.20220150
Abstract:
Tool wear monitoring is an important issue in the machining field, and the tool wear monitoring method that is based on the change of machine tool power has been widely studied. For the micro milling process, it is difficult to monitor the change of machine tool power caused by tool wear by traditional methods, because the ratio of material cutting power to machine total power is very small. This article proposes a new method to monitor the wear of the micro milling cutter based on the cutting power consumption. Based on the cutting force, the material cutting power consumption is modeled. Combined with the material removal volume, unit power consumption (UPC) model is established. When the cutting parameters are fixed, the influence of tool wear on UPC is analyzed from the perspective of tangential shearing force coefficient and tangential ploughing force coefficient. Several tool wear experiments are carried out by milling aluminum alloy 7075 with the cemented carbide end milling cutters, and the change trend of UPC is monitored. By correlating the change trend of UPC with the tool wear, it is proved that the proposed method can be used for tool wear monitoring in the micro milling process.
Tool wear monitoring is an important issue in the machining field, and the tool wear monitoring method that is based on the change of machine tool power has been widely studied. For the micro milling process, it is difficult to monitor the change of machine tool power caused by tool wear by traditional methods, because the ratio of material cutting power to machine total power is very small. This article proposes a new method to monitor the wear of the micro milling cutter based on the cutting power consumption. Based on the cutting force, the material cutting power consumption is modeled. Combined with the material removal volume, unit power consumption (UPC) model is established. When the cutting parameters are fixed, the influence of tool wear on UPC is analyzed from the perspective of tangential shearing force coefficient and tangential ploughing force coefficient. Several tool wear experiments are carried out by milling aluminum alloy 7075 with the cemented carbide end milling cutters, and the change trend of UPC is monitored. By correlating the change trend of UPC with the tool wear, it is proved that the proposed method can be used for tool wear monitoring in the micro milling process.
2022, 41(6): 885-890.
doi: 10.13433/j.cnki.1003-8728.20200389
Abstract:
The wave generator is the key to study the force characteristics of the flexspline. In order to increase the life of the flexspline, a new cam wave generator is proposed to act on the flexspline. The profile of the modified cam is composed of two eccentric arcs and two elliptical arcs connected, and the restriction conditions such as the smooth transition between the eccentric arc and the elliptical arc, the uniform load distribution on the inner surface of the flexspline, and the good meshing performance at the meshing point are transformed into design modification from the constraints of the cam. Through calculation examples, the curvature changes of the inner peripheral curves of the flexspline under the action of modified cams with different parameters are analyzed, and the modified cam wave generator is selected accordingly. The finite element simulation and testing results show that, comparing with the harmonic reducer acted by the traditional elliptical cam wave generator, the stress at both ends of the ring gear of the flexspline of the harmonic reducer with the modified cam action is significantly reduced, and the stress distribution It is also more uniform, with higher transmission accuracy and longer life.
The wave generator is the key to study the force characteristics of the flexspline. In order to increase the life of the flexspline, a new cam wave generator is proposed to act on the flexspline. The profile of the modified cam is composed of two eccentric arcs and two elliptical arcs connected, and the restriction conditions such as the smooth transition between the eccentric arc and the elliptical arc, the uniform load distribution on the inner surface of the flexspline, and the good meshing performance at the meshing point are transformed into design modification from the constraints of the cam. Through calculation examples, the curvature changes of the inner peripheral curves of the flexspline under the action of modified cams with different parameters are analyzed, and the modified cam wave generator is selected accordingly. The finite element simulation and testing results show that, comparing with the harmonic reducer acted by the traditional elliptical cam wave generator, the stress at both ends of the ring gear of the flexspline of the harmonic reducer with the modified cam action is significantly reduced, and the stress distribution It is also more uniform, with higher transmission accuracy and longer life.
2022, 41(6): 891-897.
doi: 10.13433/j.cnki.1003-8728.20200382
Abstract:
In order to improve the machinability of difficult-to-cut materials, this paper focus on the modelling of cutting force during quasi-intermittent vibration assisted swing cutting. Firstly, the relationship between the instantaneous shear angle and the cutting speed during the vibration-assisted swing cutting process is analyzed using the theory of thin shear plane, the change of cutting forces in the normal plane, rake face and shear plane is discussed. Secondly, according to the relationship between the maximum shear stress theory and the force in the cutting process, the relationship between each relevant angle and time t is analyzed to establish an analytical model of the cutting force. Finally, the effects of spindle speed and cutting depth on cutting force are studied through cutting experiments. The results shown that when the spindle speed increased from 10 r/min to 30 r/min, the cutting force values obtained by experiment and theory increased by 3.7 N and 4 N, respectively; When the cutting depth increased from 0.01 mm to 0.03 mm, the cutting force values obtained by experiment and theory increased by 3.6 N and 4.2 N, respectively. The experimental results are basically agreed with the analysis results of the theoretical model, which verifies the effectiveness of the proposed cutting force model.
In order to improve the machinability of difficult-to-cut materials, this paper focus on the modelling of cutting force during quasi-intermittent vibration assisted swing cutting. Firstly, the relationship between the instantaneous shear angle and the cutting speed during the vibration-assisted swing cutting process is analyzed using the theory of thin shear plane, the change of cutting forces in the normal plane, rake face and shear plane is discussed. Secondly, according to the relationship between the maximum shear stress theory and the force in the cutting process, the relationship between each relevant angle and time t is analyzed to establish an analytical model of the cutting force. Finally, the effects of spindle speed and cutting depth on cutting force are studied through cutting experiments. The results shown that when the spindle speed increased from 10 r/min to 30 r/min, the cutting force values obtained by experiment and theory increased by 3.7 N and 4 N, respectively; When the cutting depth increased from 0.01 mm to 0.03 mm, the cutting force values obtained by experiment and theory increased by 3.6 N and 4.2 N, respectively. The experimental results are basically agreed with the analysis results of the theoretical model, which verifies the effectiveness of the proposed cutting force model.
2022, 41(6): 898-904.
doi: 10.13433/j.cnki.1003-8728.20200410
Abstract:
To overcome the disadvantages of the traditional speed control system of a brushless DC motor (BLDCM), such as slow response and low precision, a new speed control strategy for the BLDCM based on the improved beetle antennae search (BAS) algorithm is proposed to optimize its PID controller parameters. Firstly, the mathematical model of the BLDCM speed and its current double closed-loop speed control system are established. Secondly, the simulation model of the BLDCM control system is built with the MATLAB/Simulink to realize the double closed-loop control. The current loop adopts the traditional PID control, and the speed loop adopts the improved beetle antennae search algorithm to optimize the PID control. The simulation verification of no-load, speed step and sudden load is carried out. Finally, the hardware experimental platform is built based on the TMS320F28335 chip for experimental verification. The simulation results show that the speed control system has good dynamic and static characteristics, fast speed response and strong anti-interference.
To overcome the disadvantages of the traditional speed control system of a brushless DC motor (BLDCM), such as slow response and low precision, a new speed control strategy for the BLDCM based on the improved beetle antennae search (BAS) algorithm is proposed to optimize its PID controller parameters. Firstly, the mathematical model of the BLDCM speed and its current double closed-loop speed control system are established. Secondly, the simulation model of the BLDCM control system is built with the MATLAB/Simulink to realize the double closed-loop control. The current loop adopts the traditional PID control, and the speed loop adopts the improved beetle antennae search algorithm to optimize the PID control. The simulation verification of no-load, speed step and sudden load is carried out. Finally, the hardware experimental platform is built based on the TMS320F28335 chip for experimental verification. The simulation results show that the speed control system has good dynamic and static characteristics, fast speed response and strong anti-interference.
2022, 41(6): 905-911.
doi: 10.13433/j.cnki.1003-8728.20200414
Abstract:
Considering that traditional methods for rolling bearing condition identification were difficulty in manual feature extraction of bearing vibration signals, a new method based on enhanced empirical wavelet decomposition (EEWD) with self-organizing deep network (SODN) was proposed. Firstly, the segmentation method of spectrum of empirical wavelet decomposition was enhanced, and the vibration signals of rolling bearings were adaptively decomposed into several intrinsic modal functions. The intrinsic modal functions which can best reflect the condition characteristics of the raw signals were selected by the comprehensive evaluation index and then reconstructed. Secondly, the self-organizing deep network was constructed. Finally, the reconstructed signals were fed into SODN for automatic feature learning and automatic condition identification. The experimental results indicate that the method based EEWD and SODN is superior than other deep learning methods in signals feature extraction and condition recognition accuracy.
Considering that traditional methods for rolling bearing condition identification were difficulty in manual feature extraction of bearing vibration signals, a new method based on enhanced empirical wavelet decomposition (EEWD) with self-organizing deep network (SODN) was proposed. Firstly, the segmentation method of spectrum of empirical wavelet decomposition was enhanced, and the vibration signals of rolling bearings were adaptively decomposed into several intrinsic modal functions. The intrinsic modal functions which can best reflect the condition characteristics of the raw signals were selected by the comprehensive evaluation index and then reconstructed. Secondly, the self-organizing deep network was constructed. Finally, the reconstructed signals were fed into SODN for automatic feature learning and automatic condition identification. The experimental results indicate that the method based EEWD and SODN is superior than other deep learning methods in signals feature extraction and condition recognition accuracy.
2022, 41(6): 912-921.
doi: 10.13433/j.cnki.1003-8728.20220152
Abstract:
Safety is critical to the dive work of manned submersibles. It is particularly important to reduce the potential threat to safety caused by visual obstacles during the operation and to shorten the dark adaptation reaction time of submariners. Dark adaptation is an important visual factor affecting the operation of submariners. Repeated switching and adaptation to high-contrast brightness environments will prolong the dark adaptation time of human eyes, thereby affecting the safety and accuracy of submersible operations. In this paper, aiming at the lighting environment of submarine operation area, according to the transition lighting method, the transition screen lighting is used to compensate the dark adaptation reaction time of human eyes under harsh lighting conditions. In the experiment, by changing the brightness level of the transition screen and the observation time, the optimal brightness and time range of the transition lighting were evaluated to achieve visual optimization and ensure the safety of the submariners' operation.
Safety is critical to the dive work of manned submersibles. It is particularly important to reduce the potential threat to safety caused by visual obstacles during the operation and to shorten the dark adaptation reaction time of submariners. Dark adaptation is an important visual factor affecting the operation of submariners. Repeated switching and adaptation to high-contrast brightness environments will prolong the dark adaptation time of human eyes, thereby affecting the safety and accuracy of submersible operations. In this paper, aiming at the lighting environment of submarine operation area, according to the transition lighting method, the transition screen lighting is used to compensate the dark adaptation reaction time of human eyes under harsh lighting conditions. In the experiment, by changing the brightness level of the transition screen and the observation time, the optimal brightness and time range of the transition lighting were evaluated to achieve visual optimization and ensure the safety of the submariners' operation.
2022, 41(6): 922-928.
doi: 10.13433/j.cnki.1003-8728.20200409
Abstract:
A multi-objective topological optimization method was used to study the material distribution of a compliant mechanism that satisfies the requirements of a field-artillery rocket loading system. The solid isotropic material with penalization was used as the topological optimization method. The weighted coefficient method was used to define the natural frequency objective function. The compromise programming method was used to define the multi-objective topology optimization function of static stiffness and dynamic vibration frequency. No-load condition is simulated with equal-force load, and load condition is simulated with displacement load. a topology that simultaneously meets the requirements of stiffness in no-load, flexibility in load and low-order vibration frequency of the compliant mechanism is obtained through the optimization with the HyperWorks. Finally, the simulation analysis of the optimized compliant mechanism is carried out, and the effectiveness of the optimization results is verified.
A multi-objective topological optimization method was used to study the material distribution of a compliant mechanism that satisfies the requirements of a field-artillery rocket loading system. The solid isotropic material with penalization was used as the topological optimization method. The weighted coefficient method was used to define the natural frequency objective function. The compromise programming method was used to define the multi-objective topology optimization function of static stiffness and dynamic vibration frequency. No-load condition is simulated with equal-force load, and load condition is simulated with displacement load. a topology that simultaneously meets the requirements of stiffness in no-load, flexibility in load and low-order vibration frequency of the compliant mechanism is obtained through the optimization with the HyperWorks. Finally, the simulation analysis of the optimized compliant mechanism is carried out, and the effectiveness of the optimization results is verified.
2022, 41(6): 929-935.
doi: 10.13433/j.cnki.1003-8728.20200415
Abstract:
Aiming at the poor intake uniformity in a four-cylinder diesel methanol dual-fuel engine, a simulation model for diesel methanol dual-fuel engine was constructed with GT-Power software in order to analyze the structural parameters of the intake manifold and intake manifold and the influence of the intake timing on the intake uniformity. Taking the diameter and length of the intake manifold, the diameter of the intake manifold of the 2nd and 3rd cylinders, and the intake timing as the optimization variables, the response surface model is established with the design goal of reducing the unevenness of the intake air, and combined with multiple islands Genetic algorithm for optimization. The optimization results show that by reducing the diameter of the intake manifold, the length of the intake manifold and the intake timing, and increasing the geometric parameters of the intake manifold diameter of the 2nd and 3rd cylinders, the flow quality of air and methanol in the intake manifold is improved, and the intake uniformity in the engine is reduced from 10.35% to 2.19% of the original engine.
Aiming at the poor intake uniformity in a four-cylinder diesel methanol dual-fuel engine, a simulation model for diesel methanol dual-fuel engine was constructed with GT-Power software in order to analyze the structural parameters of the intake manifold and intake manifold and the influence of the intake timing on the intake uniformity. Taking the diameter and length of the intake manifold, the diameter of the intake manifold of the 2nd and 3rd cylinders, and the intake timing as the optimization variables, the response surface model is established with the design goal of reducing the unevenness of the intake air, and combined with multiple islands Genetic algorithm for optimization. The optimization results show that by reducing the diameter of the intake manifold, the length of the intake manifold and the intake timing, and increasing the geometric parameters of the intake manifold diameter of the 2nd and 3rd cylinders, the flow quality of air and methanol in the intake manifold is improved, and the intake uniformity in the engine is reduced from 10.35% to 2.19% of the original engine.
2022, 41(6): 936-947.
doi: 10.13433/j.cnki.1003-8728.20200416
Abstract:
The gearshift process control of wet dual clutch transmission is key to its quality improvement. This paper proposes a gearshift control algorithm based on friction parameters estimation. Firstly, based on the extended Kalman filter, the method for estimating the torques transmitted by two clutches during the gearshift process of the wet dual-clutch transmission is designed. Secondly, the friction coefficient model of the wet clutch is established based on the Stribeck friction model and its corresponding coefficients are estimated with the recursive least squares, and then the real-time dynamic friction coefficient during the gearshift process are calculated with the Stribeck friction model. Finally, the required torques of two clutches are optimized through the model predictive control during gearshift, and then the required oil pressure of a hydraulic actuator is inversely deduced with the required torques and the estimated dynamic friction coefficient to improve the gearshift quality of a vehicle. Based on the MATLAB/Simulink, the vehicle model equipped with the wet dual-clutch transmission is built and the proposed gearshift control algorithm is verified with simulation. The simulation results show that the jerk and friction work of the wet dual clutches during their gearshift process are reduced with the use of the proposed gearshift control algorithm. Its effectiveness for improving the gearshift quality of wet dual-clutch transmission is verified.
The gearshift process control of wet dual clutch transmission is key to its quality improvement. This paper proposes a gearshift control algorithm based on friction parameters estimation. Firstly, based on the extended Kalman filter, the method for estimating the torques transmitted by two clutches during the gearshift process of the wet dual-clutch transmission is designed. Secondly, the friction coefficient model of the wet clutch is established based on the Stribeck friction model and its corresponding coefficients are estimated with the recursive least squares, and then the real-time dynamic friction coefficient during the gearshift process are calculated with the Stribeck friction model. Finally, the required torques of two clutches are optimized through the model predictive control during gearshift, and then the required oil pressure of a hydraulic actuator is inversely deduced with the required torques and the estimated dynamic friction coefficient to improve the gearshift quality of a vehicle. Based on the MATLAB/Simulink, the vehicle model equipped with the wet dual-clutch transmission is built and the proposed gearshift control algorithm is verified with simulation. The simulation results show that the jerk and friction work of the wet dual clutches during their gearshift process are reduced with the use of the proposed gearshift control algorithm. Its effectiveness for improving the gearshift quality of wet dual-clutch transmission is verified.
2022, 41(6): 948-953.
doi: 10.13433/j.cnki.1003-8728.20200466
Abstract:
Based on the calculation method of natural frequency of the new type honeycomb structure non-pneumatic tire, the natural frequency calculation formula of the bird's nest structure non-pneumatic tire is studied and deduced. The influence of various structural parameters on the natural frequency of the bird's nest structure is analyzed, and the factors affecting the natural frequency of the bird's nest structure non-pneumatic tire are studied. The finite element simulation of ABAQUS is used to verify the correctness of the theory calculation. Using the method of modal analysis, the influence of the number of spoke arrays on the natural frequency of the bird's nest structure non-pneumatic tire is studied, and the vibration frequency of the non-pneumatic tire under load is analyzed, and the vibration frequency change law of the pneumatic tire under load is compared. The results show that the non-pneumatic tire with bird's nest structure is more rigid and more advantageous when loaded.
Based on the calculation method of natural frequency of the new type honeycomb structure non-pneumatic tire, the natural frequency calculation formula of the bird's nest structure non-pneumatic tire is studied and deduced. The influence of various structural parameters on the natural frequency of the bird's nest structure is analyzed, and the factors affecting the natural frequency of the bird's nest structure non-pneumatic tire are studied. The finite element simulation of ABAQUS is used to verify the correctness of the theory calculation. Using the method of modal analysis, the influence of the number of spoke arrays on the natural frequency of the bird's nest structure non-pneumatic tire is studied, and the vibration frequency of the non-pneumatic tire under load is analyzed, and the vibration frequency change law of the pneumatic tire under load is compared. The results show that the non-pneumatic tire with bird's nest structure is more rigid and more advantageous when loaded.
2022, 41(6): 954-960.
doi: 10.13433/j.cnki.1003-8728.20200418
Abstract:
Based on the numerical simulation of the SST k-ω separating vortex model and the bionic study of the shark dorsal fin, a fan blade was designed to reduce the aerodynamic noise of the fan. On the basis of the fan noise test to verify the accuracy of the numerical simulation, CATIA and STRA CCM+ are applied, and the optimization scheme is selected through the parameterized design and the orthogonal experiment method. The results show that the design based on the bionic shark dorsal fin structure can reduce the airflow separation at the trailing edge of the fan, and suppress the formation of turbulent vortices in the trailing edge area, and improve the flow field, and effectively reduce aerodynamic noise, and optimize the aerodynamics of the fan blades. The noise is reduced by 3.64 dB comparing with the original scheme.
Based on the numerical simulation of the SST k-ω separating vortex model and the bionic study of the shark dorsal fin, a fan blade was designed to reduce the aerodynamic noise of the fan. On the basis of the fan noise test to verify the accuracy of the numerical simulation, CATIA and STRA CCM+ are applied, and the optimization scheme is selected through the parameterized design and the orthogonal experiment method. The results show that the design based on the bionic shark dorsal fin structure can reduce the airflow separation at the trailing edge of the fan, and suppress the formation of turbulent vortices in the trailing edge area, and improve the flow field, and effectively reduce aerodynamic noise, and optimize the aerodynamics of the fan blades. The noise is reduced by 3.64 dB comparing with the original scheme.
2022, 41(6): 961-970.
doi: 10.13433/j.cnki.1003-8728.20200514
Abstract:
Wire and arc additive manufacturing (WAAM) has the characteristics of high material utilization, high deposition efficiency, and low equipment costs. It is one of the important metal additive manufacturing technologies. However, the large molten pool size, high heat input, and low geometric accuracy of manufactured metal parts have severely restricted the further application of this technology. In this paper, a finite element method is used to establish a thermo-mechanical coupled model for WAAM, and the thermal stress evolution in the three typical structures are studied. The influence of the substrate thickness on the thermal distortion is emphatically analyzed. The results show that the first layer has the greatest influence on the components thermal distortion by comparing with the subsequent deposited layers. To increase the substrate thickness can not only improve the stiffness and increase the constraint, but also enhance the heat dissipation and reduce the heat accumulation, which is very beneficial to reduce the final distortion and residual stress in the formed parts. For rectangular structure parts, the substrate structure and restraint methods will affect the heat conduction and stress distribution inside the components, which will greatly impact on the thermal stress distortion evolution in the formed parts.
Wire and arc additive manufacturing (WAAM) has the characteristics of high material utilization, high deposition efficiency, and low equipment costs. It is one of the important metal additive manufacturing technologies. However, the large molten pool size, high heat input, and low geometric accuracy of manufactured metal parts have severely restricted the further application of this technology. In this paper, a finite element method is used to establish a thermo-mechanical coupled model for WAAM, and the thermal stress evolution in the three typical structures are studied. The influence of the substrate thickness on the thermal distortion is emphatically analyzed. The results show that the first layer has the greatest influence on the components thermal distortion by comparing with the subsequent deposited layers. To increase the substrate thickness can not only improve the stiffness and increase the constraint, but also enhance the heat dissipation and reduce the heat accumulation, which is very beneficial to reduce the final distortion and residual stress in the formed parts. For rectangular structure parts, the substrate structure and restraint methods will affect the heat conduction and stress distribution inside the components, which will greatly impact on the thermal stress distortion evolution in the formed parts.
2022, 41(6): 971-976.
doi: 10.13433/j.cnki.1003-8728.20200469
Abstract:
Sepiolite ore powder is often prepared by mechanical impact crushing method, and the different strain rate of coarse ore compressed will lead to inconsistent crushing degree. In order to study the influence of strain rate on the mechanical properties of sepiolite, a Split Hopkinson Pressure Bar (SHPB) system was used to conduct dynamic compression tests on sepiolite specimens at five different strain rates. The results show that the dynamic compressive strength, the elastic modulus, and the failure characteristics of sepiolite show obvious strain rate effects. The dynamic compressive strength increases linearly with the increase of the strain rate; the dynamic elastic modulus increases with the increase of the strain rate; with the increase of strain rate, the failure mode changes from splitting failure to crushing failure. The higher the strain rate, the smaller the size of crushed pieces and the greater the amount of powder.
Sepiolite ore powder is often prepared by mechanical impact crushing method, and the different strain rate of coarse ore compressed will lead to inconsistent crushing degree. In order to study the influence of strain rate on the mechanical properties of sepiolite, a Split Hopkinson Pressure Bar (SHPB) system was used to conduct dynamic compression tests on sepiolite specimens at five different strain rates. The results show that the dynamic compressive strength, the elastic modulus, and the failure characteristics of sepiolite show obvious strain rate effects. The dynamic compressive strength increases linearly with the increase of the strain rate; the dynamic elastic modulus increases with the increase of the strain rate; with the increase of strain rate, the failure mode changes from splitting failure to crushing failure. The higher the strain rate, the smaller the size of crushed pieces and the greater the amount of powder.
2022, 41(6): 977-984.
doi: 10.13433/j.cnki.1003-8728.20200397
Abstract:
Accurately estimating the reliability parameters of the aircraft integral drive generator (IDG) plays a key role in mastering the failure variation law of the component and formulating maintenance strategies. Aiming at the characteristics of aircraft IDG failure data as small samples, taking Weibull distribution as an example, least squares support vector regression (LSSVR), support vector regression (SVR) and least square regression (LSR) are respectively used to estimate the reliability parameters of aircraft IDG. The accuracy, running time and stability of the three parameter estimation methods are compared and analyzed. The results show that in the case of small samples, LSSVR has the highest parameter estimation accuracy and LSR has the shortest running time; as the sample size decreases, the accuracy of the three parameter estimation methods decreases, but LSSVR has the best stability.
Accurately estimating the reliability parameters of the aircraft integral drive generator (IDG) plays a key role in mastering the failure variation law of the component and formulating maintenance strategies. Aiming at the characteristics of aircraft IDG failure data as small samples, taking Weibull distribution as an example, least squares support vector regression (LSSVR), support vector regression (SVR) and least square regression (LSR) are respectively used to estimate the reliability parameters of aircraft IDG. The accuracy, running time and stability of the three parameter estimation methods are compared and analyzed. The results show that in the case of small samples, LSSVR has the highest parameter estimation accuracy and LSR has the shortest running time; as the sample size decreases, the accuracy of the three parameter estimation methods decreases, but LSSVR has the best stability.
