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RSS2018 Vol. 37, No. 7
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2018, 37(7): 985-991.
doi: 10.13433/j.cnki.1003-8728.20180002
PDF 961KB
Abstract:
Based on the basic concept of Rayleigh damping, the basic expression of Rayleigh damping is deduced. The Rayleigh damping coefficients of structural components can be calculated by the least square method and its feasibility is verified. The laminated wood and laminated paperboard used in transformers are taken as the example, their prominent modes are obtained in the dominant frequency bands by the hammering tests. The different Rayleigh damping coefficients of them were calculated by the three existing methods and the proposed least square method, and the results are compared with the those of classical method. In addition, the harmonic responses of laminated wood and laminated paperboard under the same boundary conditions and different damping coefficients have been carried out by FEM(Finite element method) with ABAQUS software. The results show that the Rayleigh damping coefficients obtained by all methods, and the trend of the displacement response of the harmonic response analysis are almost identical. The more modes are adopted in the least square method, the smaller the errors are. It is proved that calculating the Rayleigh damping coefficients of structural components by the least square method is feasible.
Based on the basic concept of Rayleigh damping, the basic expression of Rayleigh damping is deduced. The Rayleigh damping coefficients of structural components can be calculated by the least square method and its feasibility is verified. The laminated wood and laminated paperboard used in transformers are taken as the example, their prominent modes are obtained in the dominant frequency bands by the hammering tests. The different Rayleigh damping coefficients of them were calculated by the three existing methods and the proposed least square method, and the results are compared with the those of classical method. In addition, the harmonic responses of laminated wood and laminated paperboard under the same boundary conditions and different damping coefficients have been carried out by FEM(Finite element method) with ABAQUS software. The results show that the Rayleigh damping coefficients obtained by all methods, and the trend of the displacement response of the harmonic response analysis are almost identical. The more modes are adopted in the least square method, the smaller the errors are. It is proved that calculating the Rayleigh damping coefficients of structural components by the least square method is feasible.
2018, 37(7): 992-997.
doi: 10.13433/j.cnki.1003-8728.20180003
Abstract:
Based on the theory of arcing controlling with the high-speed inner flushing flow fluid forming while machining, the rotary flushing fixture is designed. Furthermore, the dynamic characteristics of the rotary flushing fixture have the significant effect on the machining performance of the arc discharge machining. Therefore, the modal simulation analysis is conducted to explore the vibrant performance of the flushing fixture by a finite element analysis software ANSYS. The simulation results show that the vibration in some directions of the flushing rotary fixture would occur violently while machining, which results in large elastically deformation parts. The simulation analysis results show that the deformation of the elastic parts could be decreased by adopting the different material properties and geometric model, from which the structure optimization of the rotary flushing fixture could be realized.
Based on the theory of arcing controlling with the high-speed inner flushing flow fluid forming while machining, the rotary flushing fixture is designed. Furthermore, the dynamic characteristics of the rotary flushing fixture have the significant effect on the machining performance of the arc discharge machining. Therefore, the modal simulation analysis is conducted to explore the vibrant performance of the flushing fixture by a finite element analysis software ANSYS. The simulation results show that the vibration in some directions of the flushing rotary fixture would occur violently while machining, which results in large elastically deformation parts. The simulation analysis results show that the deformation of the elastic parts could be decreased by adopting the different material properties and geometric model, from which the structure optimization of the rotary flushing fixture could be realized.
2018, 37(7): 998-1004.
doi: 10.13433/j.cnki.1003-8728.2018.0701
Abstract:
According to the different physical and chemical properties of methanol fuel from gasoline, and the difficulty of cold start of methanol engine, we choose the nozzle of methanol engine as the research object. The gas-liquid two-phase VOF turbulence model in Fluent software is used to simulate the nozzle flow. The study finds that the fillet changes in the inlet nozzle and inverted cone angle changes of nozzle have certain influence on nozzle flow field. The results show that under the condition of constant pressure, the thickness of the negative pressure layer decreases with the increase of the radius of curvature at the entrance, the volume fraction of the gas phase decreases and the atomization performance decreases. With the increase of nozzle curvature radius, the flow rate increases. Increasing the inverted cone angle of the nozzle hole, the flow rate at the nozzle outlet is reduced, the mass flow rate is reduced, but the thickening of the negative pressure layer is favorable for the atomization of the methanol fuel.
According to the different physical and chemical properties of methanol fuel from gasoline, and the difficulty of cold start of methanol engine, we choose the nozzle of methanol engine as the research object. The gas-liquid two-phase VOF turbulence model in Fluent software is used to simulate the nozzle flow. The study finds that the fillet changes in the inlet nozzle and inverted cone angle changes of nozzle have certain influence on nozzle flow field. The results show that under the condition of constant pressure, the thickness of the negative pressure layer decreases with the increase of the radius of curvature at the entrance, the volume fraction of the gas phase decreases and the atomization performance decreases. With the increase of nozzle curvature radius, the flow rate increases. Increasing the inverted cone angle of the nozzle hole, the flow rate at the nozzle outlet is reduced, the mass flow rate is reduced, but the thickening of the negative pressure layer is favorable for the atomization of the methanol fuel.
2018, 37(7): 1005-1012.
doi: 10.13433/j.cnki.1003-8728.2018.0702
Abstract:
In order to improve the positioning accuracy of rock drilling robotic drilling arm, the particle swarm optimization (PSO) algorithm is often used to compensate the joint variable error of rock drilling robotic drilling arm, but there are some problems, such as low convergence speed, tending to be trapped in local optimal solution, etc. In order to solve these problems, a crossover elite opposition-based particle swarm optimization (CEOPSO) algorithm is presented and the algorithm flow is given in this paper. Aiming at the two main error factors which are parameter error and deformation error, the parameter error model of drilling arm is established by modified D-H method, and the deformation error model of the drilling arm is derived by introducing a virtual joint into the deformed joint. The crossover operator is introduced into EOPSO. The adaptive inertia weight and the crossover probability parameter control technology are adopted. On the basis of maintaining the information exchange between the individual and the optimal solution, the global searching ability of the algorithm and the positioning efficiency of drilling arm are improved by increasing the information exchange between the individual particles. Simulation results show that the CEOPSO has better optimal joint compensation value searching convergence speed and solving stability than those of PSO and EOPSO. The positioning and control performance of rock drilling robotic drilling arm can be improved effectively.
In order to improve the positioning accuracy of rock drilling robotic drilling arm, the particle swarm optimization (PSO) algorithm is often used to compensate the joint variable error of rock drilling robotic drilling arm, but there are some problems, such as low convergence speed, tending to be trapped in local optimal solution, etc. In order to solve these problems, a crossover elite opposition-based particle swarm optimization (CEOPSO) algorithm is presented and the algorithm flow is given in this paper. Aiming at the two main error factors which are parameter error and deformation error, the parameter error model of drilling arm is established by modified D-H method, and the deformation error model of the drilling arm is derived by introducing a virtual joint into the deformed joint. The crossover operator is introduced into EOPSO. The adaptive inertia weight and the crossover probability parameter control technology are adopted. On the basis of maintaining the information exchange between the individual and the optimal solution, the global searching ability of the algorithm and the positioning efficiency of drilling arm are improved by increasing the information exchange between the individual particles. Simulation results show that the CEOPSO has better optimal joint compensation value searching convergence speed and solving stability than those of PSO and EOPSO. The positioning and control performance of rock drilling robotic drilling arm can be improved effectively.
2018, 37(7): 1013-1021.
doi: 10.13433/j.cnki.1003-8728.2018.0703
Abstract:
In this paper, the research considers the inner regularity of the signal, which improves the method of boundary extending based on the method of the nearest similarity distance continuation and parallel extending method. The regularity strength of signal is determined by calculating the similarity distance between the boundary wave and any internal signal wave. When the inherent regularity is strong, the nearest similarity distance continuation method is conducted to maintain the inherent tendency to the greatest extent; while the signal is week regularity and the signal edge changes abnormally, the local information at the edges is considered only to conduct the parallel extending method. In order to prove the improved algorithm, this paper calculates the matching distance, waveform similarity coefficient and error in marginal spectrum of frequency through the simulation analysis and tests of fault diagnosis of rolling bearings of IMFs and simulation signal component. The results demonstrate that matching distances are 3.378 7, 7.240 4, 7.390 7, waveform similarity coefficients are 0.999 9, 0.997 7, 0.903 4 and error in marginal spectrum in 5 Hz is 6.2% by the improved algorithm. Containers among directly continuation, parallel extending method, this method can suppress end effect of EMD. This method can improve the decomposition accuracy and achieve availably fault feature extraction, which can provide the reference for fault diagnosis of machine.
In this paper, the research considers the inner regularity of the signal, which improves the method of boundary extending based on the method of the nearest similarity distance continuation and parallel extending method. The regularity strength of signal is determined by calculating the similarity distance between the boundary wave and any internal signal wave. When the inherent regularity is strong, the nearest similarity distance continuation method is conducted to maintain the inherent tendency to the greatest extent; while the signal is week regularity and the signal edge changes abnormally, the local information at the edges is considered only to conduct the parallel extending method. In order to prove the improved algorithm, this paper calculates the matching distance, waveform similarity coefficient and error in marginal spectrum of frequency through the simulation analysis and tests of fault diagnosis of rolling bearings of IMFs and simulation signal component. The results demonstrate that matching distances are 3.378 7, 7.240 4, 7.390 7, waveform similarity coefficients are 0.999 9, 0.997 7, 0.903 4 and error in marginal spectrum in 5 Hz is 6.2% by the improved algorithm. Containers among directly continuation, parallel extending method, this method can suppress end effect of EMD. This method can improve the decomposition accuracy and achieve availably fault feature extraction, which can provide the reference for fault diagnosis of machine.
2018, 37(7): 1022-1026.
doi: 10.13433/j.cnki.1003-8728.2018.0704
Abstract:
A vibration-driver based on voice coil linear motor is designed, and this vibration-driver moves in a single-way direction, is a piecewise linear system and forms a non-smooth dynamic system. Its impact vibration equation is established according to the different state of motion. The periodic motion and the parameter distribution law of the vibration-driver is studied based on the non-smooth dynamics theory. The matching rules between average driving velocity and corresponding parameter domain (current frequency and amplitude, mass ratio) are analyzed. The numerical simulation shows that the average driving velocity of the vibration-driver reaches maximum when the vibration-driver has a 1/1 periodic motion and a large impact velocity. The magnitude of the current has a great influence on the average driving velocity but has no effect on the distribution of frequency band. The effect of the gap on the average driving velocity and the distribution of frequency band is small. The influence of the mass ratio on the average drive velocity and its distribution of frequency band is obvious.
A vibration-driver based on voice coil linear motor is designed, and this vibration-driver moves in a single-way direction, is a piecewise linear system and forms a non-smooth dynamic system. Its impact vibration equation is established according to the different state of motion. The periodic motion and the parameter distribution law of the vibration-driver is studied based on the non-smooth dynamics theory. The matching rules between average driving velocity and corresponding parameter domain (current frequency and amplitude, mass ratio) are analyzed. The numerical simulation shows that the average driving velocity of the vibration-driver reaches maximum when the vibration-driver has a 1/1 periodic motion and a large impact velocity. The magnitude of the current has a great influence on the average driving velocity but has no effect on the distribution of frequency band. The effect of the gap on the average driving velocity and the distribution of frequency band is small. The influence of the mass ratio on the average drive velocity and its distribution of frequency band is obvious.
2018, 37(7): 1027-1033.
doi: 10.13433/j.cnki.1003-8728.2018.0705
Abstract:
An observer-based input-output control strategy is presented to track the joint angle and to eliminate the flexible vibration for planar multi-link flexible manipulators. The Lagrangian approach is applied to build the dynamic model of the flexible manipulator. Based on Euler-Bernoulli beam theory, the finite-dimensional assumed modes method is used to describe the elastic vibration of the flexible manipulator. The control strategy presented is developed based on input-output feedback linearization theory. The feedback controller is designed to control the joint angle by redefining output variables near the end point of the arm. A non-linear observer is design to estimate the amplitude variation of elastic vibration. The observed values are used to build a vibration-suppressed controller. The nonlinear stability of dynamic system and the uniform convergence of the error are proved by Lyapunov theorem. Genetic algorithms is introduced to optimize the gains of vibration-suppressed controller. Simulation results have proved the effectiveness of the control strategy.
An observer-based input-output control strategy is presented to track the joint angle and to eliminate the flexible vibration for planar multi-link flexible manipulators. The Lagrangian approach is applied to build the dynamic model of the flexible manipulator. Based on Euler-Bernoulli beam theory, the finite-dimensional assumed modes method is used to describe the elastic vibration of the flexible manipulator. The control strategy presented is developed based on input-output feedback linearization theory. The feedback controller is designed to control the joint angle by redefining output variables near the end point of the arm. A non-linear observer is design to estimate the amplitude variation of elastic vibration. The observed values are used to build a vibration-suppressed controller. The nonlinear stability of dynamic system and the uniform convergence of the error are proved by Lyapunov theorem. Genetic algorithms is introduced to optimize the gains of vibration-suppressed controller. Simulation results have proved the effectiveness of the control strategy.
2018, 37(7): 1034-1040.
doi: 10.13433/j.cnki.1003-8728.2018.0706
Abstract:
To improve the static and dynamic performance and lightness of a machine tool. This paper take a CNC lathe's oblique bed as the prototype preliminary design of a basalt fiber polymer concrete (BFPC) oblique bed and analyze the force of the oblique bed under typical working conditions. The static and dynamic characteristics of the two kinds of oblique bed are simulated and analyzed. Then, the optimization design of the BFPC oblique bed is carried out according to the topological optimization results and manufacturing processes of the BFPC oblique bed, whose structure is reconstructed. With the factor of its weight reduction pore size taken into consideration, the natural frequency of the first six modes are used as experimental indexes. Finally, experiments on single-factor rotation is conducted to determine the numerical value. The static and dynamic performance and lightness of the optimized BFPC bed are simulated and calculated and then compared with the prototype and optimized BFPC oblique beds before their corresponding performance is analyzed. The results show that the topologically optimized BFPC oblique bed is obviously better than the latter two in terms of static and dynamic performance and lightness.
To improve the static and dynamic performance and lightness of a machine tool. This paper take a CNC lathe's oblique bed as the prototype preliminary design of a basalt fiber polymer concrete (BFPC) oblique bed and analyze the force of the oblique bed under typical working conditions. The static and dynamic characteristics of the two kinds of oblique bed are simulated and analyzed. Then, the optimization design of the BFPC oblique bed is carried out according to the topological optimization results and manufacturing processes of the BFPC oblique bed, whose structure is reconstructed. With the factor of its weight reduction pore size taken into consideration, the natural frequency of the first six modes are used as experimental indexes. Finally, experiments on single-factor rotation is conducted to determine the numerical value. The static and dynamic performance and lightness of the optimized BFPC bed are simulated and calculated and then compared with the prototype and optimized BFPC oblique beds before their corresponding performance is analyzed. The results show that the topologically optimized BFPC oblique bed is obviously better than the latter two in terms of static and dynamic performance and lightness.
2018, 37(7): 1041-1047.
doi: 10.13433/j.cnki.1003-8728.2018.0707
Abstract:
In order to control the amplitude catastrophe of the rotor system with nonlinear stiffness, the rotor system dynamics model is established by introducing electromagnetic support with nonlinear variable stiffness function. The primary resonance frequency response equation of the rotor system is derived by the averaging method. The amplitude catastrophe region and unstable region of the rotor system are obtained based on the catastrophe theory and singular point stability theory. Finally, the influences of nonlinear electromagnetic support stiffness on bifurcation catastrophe area, unstable region and amplitude characteristic curve were discussed though the numerical simulation examples. The results show that the amplitude catastrophe is completely controlled when the exciting force amplitude is in the gradient region after control. Conversely, the amplitude characteristic curve still has multi valued characteristics so that the amplitude catastrophe is only partially controlled.
In order to control the amplitude catastrophe of the rotor system with nonlinear stiffness, the rotor system dynamics model is established by introducing electromagnetic support with nonlinear variable stiffness function. The primary resonance frequency response equation of the rotor system is derived by the averaging method. The amplitude catastrophe region and unstable region of the rotor system are obtained based on the catastrophe theory and singular point stability theory. Finally, the influences of nonlinear electromagnetic support stiffness on bifurcation catastrophe area, unstable region and amplitude characteristic curve were discussed though the numerical simulation examples. The results show that the amplitude catastrophe is completely controlled when the exciting force amplitude is in the gradient region after control. Conversely, the amplitude characteristic curve still has multi valued characteristics so that the amplitude catastrophe is only partially controlled.
2018, 37(7): 1048-1054.
doi: 10.13433/j.cnki.1003-8728.2018.0708
Abstract:
In order to improve its capacity, while loss, critical speed and control stiffness are considered, the design of the structural dimensions of the radial magnetic bearing should be optimal. This paper introduces the fruit fly optimization algorithm (FOA) into the optimal design of the radial magnetic bearing(RMB) for flywheel energy storage. Its size parameter is used as an optimization variable, and its multi-objective optimization is carried out to optimize its capacity, volume and axial length. Through optimization, the carrying capacity of the RMB increases by 50%, and its axial length and volume decrease by 30.6% and 19.3% respectively. The results show that the optimization algorithm designed in this paper is simple and effective, reduces the optimization workload and has universal applicability.
In order to improve its capacity, while loss, critical speed and control stiffness are considered, the design of the structural dimensions of the radial magnetic bearing should be optimal. This paper introduces the fruit fly optimization algorithm (FOA) into the optimal design of the radial magnetic bearing(RMB) for flywheel energy storage. Its size parameter is used as an optimization variable, and its multi-objective optimization is carried out to optimize its capacity, volume and axial length. Through optimization, the carrying capacity of the RMB increases by 50%, and its axial length and volume decrease by 30.6% and 19.3% respectively. The results show that the optimization algorithm designed in this paper is simple and effective, reduces the optimization workload and has universal applicability.
2018, 37(7): 1055-1060.
doi: 10.13433/j.cnki.1003-8728.2018.0709
Abstract:
In order to solve the low plasticity, high brittleness and poor surface processability of titanium-aluminum based alloy, the surface integrity in the process of TiAl based alloy abrasive belt grinding was studied with the orthogonal method. The factors influencing the material removal rate and surface quality of TiAl based alloy abrasive belt are summarized, and the optimal processing parameters is A3B3C2D2 by adopting the gray correlation method. TiAl based alloy abrasive belt grinding was carried out under the best technological parameters by analyzing the abrasive wear process of TiAl based alloy abrasive belt grinding and the surface topography of the workpiece before and after grinding. The result shows that the abrasive belt grinding has the good grinding effect on the TiAl based alloy, and it can be used in the precision machining of TiAl based alloy. The present work provides the new processing method for surface precision processing of TiAl based alloy.
In order to solve the low plasticity, high brittleness and poor surface processability of titanium-aluminum based alloy, the surface integrity in the process of TiAl based alloy abrasive belt grinding was studied with the orthogonal method. The factors influencing the material removal rate and surface quality of TiAl based alloy abrasive belt are summarized, and the optimal processing parameters is A3B3C2D2 by adopting the gray correlation method. TiAl based alloy abrasive belt grinding was carried out under the best technological parameters by analyzing the abrasive wear process of TiAl based alloy abrasive belt grinding and the surface topography of the workpiece before and after grinding. The result shows that the abrasive belt grinding has the good grinding effect on the TiAl based alloy, and it can be used in the precision machining of TiAl based alloy. The present work provides the new processing method for surface precision processing of TiAl based alloy.
2018, 37(7): 1061-1067.
doi: 10.13433/j.cnki.1003-8728.2018.0710
Abstract:
The form of bolt connection in engineering is various; especially some parts need sealing, noise reduction and so on. A non-metallic gasket is used in the bolt connection. There are so many hardness styles of non-metallic gaskets that we can choose to improve the quality of products due to the lack of standards. To study the influence of the hardness of the non-metallic gasket on the loosening life of the bolt connection, 3 hardness (shore hardness D are 7, 10, 15 respeatively) non-metallic gaskets with the thickness of 20 mm are chosen to do some experiments. The experimental results are compared with those on ordinary bolt connection and show that the harder non-metallic gasket can give the bolt connection a longer loosening life.
The form of bolt connection in engineering is various; especially some parts need sealing, noise reduction and so on. A non-metallic gasket is used in the bolt connection. There are so many hardness styles of non-metallic gaskets that we can choose to improve the quality of products due to the lack of standards. To study the influence of the hardness of the non-metallic gasket on the loosening life of the bolt connection, 3 hardness (shore hardness D are 7, 10, 15 respeatively) non-metallic gaskets with the thickness of 20 mm are chosen to do some experiments. The experimental results are compared with those on ordinary bolt connection and show that the harder non-metallic gasket can give the bolt connection a longer loosening life.
2018, 37(7): 1068-1075.
doi: 10.13433/j.cnki.1003-8728.20180124
Abstract:
To reveal the influence of static magnetic field on the shape, heat and mass transfer of welding arc, the numerical model of a welding arc is established to compare and analyze its heat and mass transfer processes in the conventional welding, external longitudinal magnetic field and transverse magnetic field-assisted welding. The analysis results show that the longitudinal magnetic field can decrease the current density and temperature of the welding arc near its substrate. In addition, the peak temperature and pressure of the welding arc are reduced and the negative pressure appears at the center of the welding arc under the external longitudinal magnetic field. The transverse magnetic field makes the welding arc inclined to one side; the current density, temperature and arc pressure at the center of the welding arc are smaller when no external longitudinal magnetic field is applied. The changes in arc shape, heat transfer and mass transfer result in the heat and force interaction between welding arc and metal and further result in changes in heat and mass transfer processes of the molten pool.
To reveal the influence of static magnetic field on the shape, heat and mass transfer of welding arc, the numerical model of a welding arc is established to compare and analyze its heat and mass transfer processes in the conventional welding, external longitudinal magnetic field and transverse magnetic field-assisted welding. The analysis results show that the longitudinal magnetic field can decrease the current density and temperature of the welding arc near its substrate. In addition, the peak temperature and pressure of the welding arc are reduced and the negative pressure appears at the center of the welding arc under the external longitudinal magnetic field. The transverse magnetic field makes the welding arc inclined to one side; the current density, temperature and arc pressure at the center of the welding arc are smaller when no external longitudinal magnetic field is applied. The changes in arc shape, heat transfer and mass transfer result in the heat and force interaction between welding arc and metal and further result in changes in heat and mass transfer processes of the molten pool.
2018, 37(7): 1076-1081.
doi: 10.13433/j.cnki.1003-8728.20180084
Abstract:
Aiming at under-process planning and process planning optimization in the manufacturing process of complex part with this hybrid manufacturing technology, a hybrid process planning algorithm for additive and subtractive manufacturing is presented in this paper. By performing four steps including part decomposition, building direction determination, additive and subtractive operation sequence generation and operation sequence optimization, a proper operation sequence with time optimization is generated at last, which can realize the precision fabrication of complex part. Moreover, the experimental case is performed and which demonstrates the feasibility and advantage of present algorithm.
Aiming at under-process planning and process planning optimization in the manufacturing process of complex part with this hybrid manufacturing technology, a hybrid process planning algorithm for additive and subtractive manufacturing is presented in this paper. By performing four steps including part decomposition, building direction determination, additive and subtractive operation sequence generation and operation sequence optimization, a proper operation sequence with time optimization is generated at last, which can realize the precision fabrication of complex part. Moreover, the experimental case is performed and which demonstrates the feasibility and advantage of present algorithm.
2018, 37(7): 1082-1088.
doi: 10.13433/j.cnki.1003-8728.2018.0711
Abstract:
In order to improve the accuracy of vehicle anti-collision warning algorithm and broaden the scope of the warning system, an improved security warning distance algorithm based on the Berkeley model is proposed. ZigBee wireless communication is used to collect the operating conditions of the vehicle. Chebyshev law of large numbers is used to preprocess the reaction time, the braking effect time and the speed of the front car. By analyzing the motion state of the vehicle, deriving the formula of safe warning distance, the collision avoidance warning is realized. To verify the validity of the algorithm, MATLAB is used to simulate the improved model algorithm. The results show that the improved model can improve the accuracy of early warning and meet the warning demand of different braking speeds.
In order to improve the accuracy of vehicle anti-collision warning algorithm and broaden the scope of the warning system, an improved security warning distance algorithm based on the Berkeley model is proposed. ZigBee wireless communication is used to collect the operating conditions of the vehicle. Chebyshev law of large numbers is used to preprocess the reaction time, the braking effect time and the speed of the front car. By analyzing the motion state of the vehicle, deriving the formula of safe warning distance, the collision avoidance warning is realized. To verify the validity of the algorithm, MATLAB is used to simulate the improved model algorithm. The results show that the improved model can improve the accuracy of early warning and meet the warning demand of different braking speeds.
2018, 37(7): 1089-1095.
doi: 10.13433/j.cnki.1003-8728.2018.0712
Abstract:
In order to achieve anti-lock control of electric vehicle, a hybrid anti-lock braking system in electric vehicle is presented. Firstly, the models for hydraulic and motor anti-lock braking are established; secondly the hybrid anti-lock braking control mode is designed, according to the size of tire-road adhesion coefficient; finally, the hybrid anti-lock braking system is designed, based on the fuzzy-PID control. The simulation models for hybrid and hydraulic anti-lock braking are built simultaneously in MATLAB/Simulink in order to make comparative analysis, and the result shows that:on the different adhesion coefficient road, the hybrid braking can effectively control the slip ratio, shorten the braking time and distance, and recover the braking energy; on the joint-adhesion road, the hybrid braking can achieve an ideal control effect, and the system has rapid response and good robustness.
In order to achieve anti-lock control of electric vehicle, a hybrid anti-lock braking system in electric vehicle is presented. Firstly, the models for hydraulic and motor anti-lock braking are established; secondly the hybrid anti-lock braking control mode is designed, according to the size of tire-road adhesion coefficient; finally, the hybrid anti-lock braking system is designed, based on the fuzzy-PID control. The simulation models for hybrid and hydraulic anti-lock braking are built simultaneously in MATLAB/Simulink in order to make comparative analysis, and the result shows that:on the different adhesion coefficient road, the hybrid braking can effectively control the slip ratio, shorten the braking time and distance, and recover the braking energy; on the joint-adhesion road, the hybrid braking can achieve an ideal control effect, and the system has rapid response and good robustness.
2018, 37(7): 1096-1101.
doi: 10.13433/j.cnki.1003-8728.2018.0713
Abstract:
Using the radar-graph method, material machinability could be evaluated qualitatively and quantitatively. However, there are still two key problems to be resolved, which is the index weight determining and effective evaluation. The comprehensive evaluation method was proposed to solve the first question. The mathematical statistics method was used to process the weight of index, which was decided by the subjective or objective weighting method. The optimization model was established based on the minimizing the total deviations between the original evaluation weight and the combination weight. And the comprehensive evaluation index K contained the area vector and the perimeter vector of radar graph was defined to evaluate the material machinability quantitatively. The machinability examples of Ti6Al4V titanium alloy, AISI316L stainless steel, P20 plastic mould steel, 20 steel and normalized 45 steel were provided finally. The verification results verify the feasibility, reliability and validity of the method.
Using the radar-graph method, material machinability could be evaluated qualitatively and quantitatively. However, there are still two key problems to be resolved, which is the index weight determining and effective evaluation. The comprehensive evaluation method was proposed to solve the first question. The mathematical statistics method was used to process the weight of index, which was decided by the subjective or objective weighting method. The optimization model was established based on the minimizing the total deviations between the original evaluation weight and the combination weight. And the comprehensive evaluation index K contained the area vector and the perimeter vector of radar graph was defined to evaluate the material machinability quantitatively. The machinability examples of Ti6Al4V titanium alloy, AISI316L stainless steel, P20 plastic mould steel, 20 steel and normalized 45 steel were provided finally. The verification results verify the feasibility, reliability and validity of the method.
2018, 37(7): 1102-1106.
doi: 10.13433/j.cnki.1003-8728.2018.0714
Abstract:
Spring-back defect is considered to be a major problem in forming process of high strength steel, especially multi-stage forming, as the spring-back is more complicated due to an action of internal stress. The compensation method by adjusting tool shape geometry based on accurate spring-back prediction is the key to solve the problem. The combined hardening model for multi-stage forming is presented, and an iterated compensation method is applied with Ls-Dyna and Ls-Opt. In a self-designed experimental platform, the prediction model is shown to be more accurate in multi-axial tension and compression of DP600 comparing with other models. The compensation method is applied to the numerical simulation forthe multi-stage manufacturing process of an A-pillar, the experimental result demonstrates the feasibility and accuracy.
Spring-back defect is considered to be a major problem in forming process of high strength steel, especially multi-stage forming, as the spring-back is more complicated due to an action of internal stress. The compensation method by adjusting tool shape geometry based on accurate spring-back prediction is the key to solve the problem. The combined hardening model for multi-stage forming is presented, and an iterated compensation method is applied with Ls-Dyna and Ls-Opt. In a self-designed experimental platform, the prediction model is shown to be more accurate in multi-axial tension and compression of DP600 comparing with other models. The compensation method is applied to the numerical simulation forthe multi-stage manufacturing process of an A-pillar, the experimental result demonstrates the feasibility and accuracy.
2018, 37(7): 1107-1114.
doi: 10.13433/j.cnki.1003-8728.2018.0715
Abstract:
Based on the model for NASGRO crack propagation rate, considering the influence of the stress intensity factor amplitude threshold and the fracture toughness, the stress intensity factor amplitude was used as the driving force of the crack propagation to discuss the whole of the crack front dynamic evolution with the semi-circular shape as the initial surface crack. The influence of the position of the initial crack on the crack propagation mode was revealed, and the fatigue life distribution in different propagation modes was obtained; the distribution of stress intensity factor at the crack front and its distribution in different directions were analyzed. The fatigue comparative test of the cross welded joint was carried out, the results were in a good agreement with the simulated.
Based on the model for NASGRO crack propagation rate, considering the influence of the stress intensity factor amplitude threshold and the fracture toughness, the stress intensity factor amplitude was used as the driving force of the crack propagation to discuss the whole of the crack front dynamic evolution with the semi-circular shape as the initial surface crack. The influence of the position of the initial crack on the crack propagation mode was revealed, and the fatigue life distribution in different propagation modes was obtained; the distribution of stress intensity factor at the crack front and its distribution in different directions were analyzed. The fatigue comparative test of the cross welded joint was carried out, the results were in a good agreement with the simulated.
2018, 37(7): 1115-1119.
doi: 10.13433/j.cnki.1003-8728.2018.0716
Abstract:
SPCC sheet resistance spot welding adhesive joint was prepared and tensile shear test was carried out. The Euler-Lagrange analysis model for adhesive spot welding joint is established to extract the pressure time curve of each test point at the interface of adhesive layer, and the effect of the heating and gasification process on the weld pool is analyzed. At the same time, the ultrasonic C scanning imaging test was carried out on the spot welding joint of SPCC plate with the ultrasonic water immersion focusing method. The features of nugget area were analyzed by A scanning signal and C scanning image. The results show that the average tensile strength of the adhesive joint and the spot welded joint are 10 518.325 N and 10 164.421 N respectively, and the strength of the spot welded joint is improved by adding the adhesive layer. In the bonding process, the high pressure gas from the adhesive layer is discharged from the gap between the upper and lower plates and leaves the cavity area around the weld core after the gas is discharged. Based on the characteristics of ultrasonic C scanning images, the adhesively bonded joints are divided into the conductive adhesive zone, the cavity region after the gasification of the adhesive layer, and the nugget region. The results of the test is in an agreement well with the simulated.
SPCC sheet resistance spot welding adhesive joint was prepared and tensile shear test was carried out. The Euler-Lagrange analysis model for adhesive spot welding joint is established to extract the pressure time curve of each test point at the interface of adhesive layer, and the effect of the heating and gasification process on the weld pool is analyzed. At the same time, the ultrasonic C scanning imaging test was carried out on the spot welding joint of SPCC plate with the ultrasonic water immersion focusing method. The features of nugget area were analyzed by A scanning signal and C scanning image. The results show that the average tensile strength of the adhesive joint and the spot welded joint are 10 518.325 N and 10 164.421 N respectively, and the strength of the spot welded joint is improved by adding the adhesive layer. In the bonding process, the high pressure gas from the adhesive layer is discharged from the gap between the upper and lower plates and leaves the cavity area around the weld core after the gas is discharged. Based on the characteristics of ultrasonic C scanning images, the adhesively bonded joints are divided into the conductive adhesive zone, the cavity region after the gasification of the adhesive layer, and the nugget region. The results of the test is in an agreement well with the simulated.
2018, 37(7): 1120-1124.
doi: 10.13433/j.cnki.1003-8728.2018.0717
Abstract:
The anti-galling ability of stainless steel bolt was investigated under three conditions, i.e. slow tightening and loosening, quick tightening and loosening and quick tightening and loosening after the application of glue. The galling mechanism of stainless steel bolt was analyzed and the anti-galling schemes were proposed. The test results show that the high temperature induced by quick tightening and loosening causes the serious adhesion wear at the threads. The wear debris are accumulated within the space between the threads, which prevents the movement of the threads and finally causes the galling of the bolt. The temperature of the threads can be reduced by applyingthe glue and the reduction in the speed of tightening and loosening, which alleviates the adhesion wear and suppresses the occurrence of galling.
The anti-galling ability of stainless steel bolt was investigated under three conditions, i.e. slow tightening and loosening, quick tightening and loosening and quick tightening and loosening after the application of glue. The galling mechanism of stainless steel bolt was analyzed and the anti-galling schemes were proposed. The test results show that the high temperature induced by quick tightening and loosening causes the serious adhesion wear at the threads. The wear debris are accumulated within the space between the threads, which prevents the movement of the threads and finally causes the galling of the bolt. The temperature of the threads can be reduced by applyingthe glue and the reduction in the speed of tightening and loosening, which alleviates the adhesion wear and suppresses the occurrence of galling.
2018, 37(7): 1125-1131.
doi: 10.13433/j.cnki.1003-8728.20180120
Abstract:
To investigate the characteristics of detonation re-initiation when the detonation wave go through a sudden expansion micro-tube, numerical study was carried out in different sudden expansion ratio tubes with the stoichiometric ratio of ethylene and oxygen (or the stoichiometric ratio of hydrogen and oxygen). Simulation results showed that, both the fuel and the sudden expansion ratio would affect the detonation re-initiation, and the larger the sudden expansion ratio is, the longer the detonation distance and the time are within a certain range of sudden expansion ratio. For the same sudden expansion ratio, the time of deflagration-to-detonation transition (DDT) was shorter for C2H4/O2 mixture, but the H2/O2 mixture has a wider expansion ratio range of the sudden expansion ratio for successfully detonation re-initiation. When the sudden expansion ratio was more than 7 for H2/O2 mixture, and the sudden expansion ratio was more than 5 for C2H4/O2 mixture, the chemical reaction zone and shock wave will not be able to couple again to form a detonation wave.
To investigate the characteristics of detonation re-initiation when the detonation wave go through a sudden expansion micro-tube, numerical study was carried out in different sudden expansion ratio tubes with the stoichiometric ratio of ethylene and oxygen (or the stoichiometric ratio of hydrogen and oxygen). Simulation results showed that, both the fuel and the sudden expansion ratio would affect the detonation re-initiation, and the larger the sudden expansion ratio is, the longer the detonation distance and the time are within a certain range of sudden expansion ratio. For the same sudden expansion ratio, the time of deflagration-to-detonation transition (DDT) was shorter for C2H4/O2 mixture, but the H2/O2 mixture has a wider expansion ratio range of the sudden expansion ratio for successfully detonation re-initiation. When the sudden expansion ratio was more than 7 for H2/O2 mixture, and the sudden expansion ratio was more than 5 for C2H4/O2 mixture, the chemical reaction zone and shock wave will not be able to couple again to form a detonation wave.
2018, 37(7): 1132-1136.
doi: 10.13433/j.cnki.1003-8728.2018.0718
Abstract:
Environmental deterioration rating of aircraft structure is studied. The existing weighting methods depend on either subjective experience or objective data overly, and the rating method based on combination weighting is presented. The rating model uses analytic hierarchy process to determine the subjective weight, and the objective weight is obtained with information entropy of decision table in rough sets theory. Then the reasonable distribution coefficients between the two weight vectors are calculated with vector angle formula, and the combination weighting is obtained. Furthermore, the determination of total rating and inspection interval by rating-interval regression equation is performed. Finally, the structural significant items of a certain type aircraft are taken as examples to verify the proposed method.
Environmental deterioration rating of aircraft structure is studied. The existing weighting methods depend on either subjective experience or objective data overly, and the rating method based on combination weighting is presented. The rating model uses analytic hierarchy process to determine the subjective weight, and the objective weight is obtained with information entropy of decision table in rough sets theory. Then the reasonable distribution coefficients between the two weight vectors are calculated with vector angle formula, and the combination weighting is obtained. Furthermore, the determination of total rating and inspection interval by rating-interval regression equation is performed. Finally, the structural significant items of a certain type aircraft are taken as examples to verify the proposed method.
2018, 37(7): 1137-1142.
doi: 10.13433/j.cnki.1003-8728.20180007
Abstract:
The compensation of the throat area accuracy for the axial-symmetric vectoring exhaust nozzle(AVEN) by the control compensation system is studied. The kinematic and inverse kinematics models of throat are established. The precision of the throat is analyzed by considering the effect of the machining error, input error and the gap error of the hinge. The Open-loop inverse mode control and mononeuric PID & inverse mode feedforward control are used to design the control compensation system to realize the compensation of the precision of the throat area. The method of simulation test shows that the latter has better compensation effect on the throat area. With the system compensation, deviation of throat area is less than 1%, which provids important reference for the precision and compensation control of the axial-symmetric vectoring exhaust nozzle.
The compensation of the throat area accuracy for the axial-symmetric vectoring exhaust nozzle(AVEN) by the control compensation system is studied. The kinematic and inverse kinematics models of throat are established. The precision of the throat is analyzed by considering the effect of the machining error, input error and the gap error of the hinge. The Open-loop inverse mode control and mononeuric PID & inverse mode feedforward control are used to design the control compensation system to realize the compensation of the precision of the throat area. The method of simulation test shows that the latter has better compensation effect on the throat area. With the system compensation, deviation of throat area is less than 1%, which provids important reference for the precision and compensation control of the axial-symmetric vectoring exhaust nozzle.
2018, 37(7): 1143-1148.
doi: 10.13433/j.cnki.1003-8728.2018.0719
Abstract:
In order to resolve the external disturbances and model parameter uncertainty during the unmanned aerial vehicle(UAV) flight process, a robust H∞/S-plane model control algorithm was designed, in which the outer ring adopts the S-plane control algorithm with strong nonlinear, and the inner ring adopts robust H∞ control with strong robustness. The nominal model of a certain UAV was simulated to verify respectively the effect of H∞/S model control algorithm to the height of UAV in the conditions of external interference, parameter perturbation and without external interference. The results show that the H∞/S-plane model control algorithm is concise with good convergence, accuracy, robustness and dynamic performance compared with the H∞/PD model control algorithm, which make it more suitable for UAV height control.
In order to resolve the external disturbances and model parameter uncertainty during the unmanned aerial vehicle(UAV) flight process, a robust H∞/S-plane model control algorithm was designed, in which the outer ring adopts the S-plane control algorithm with strong nonlinear, and the inner ring adopts robust H∞ control with strong robustness. The nominal model of a certain UAV was simulated to verify respectively the effect of H∞/S model control algorithm to the height of UAV in the conditions of external interference, parameter perturbation and without external interference. The results show that the H∞/S-plane model control algorithm is concise with good convergence, accuracy, robustness and dynamic performance compared with the H∞/PD model control algorithm, which make it more suitable for UAV height control.
