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RSS2018 Vol. 37, No. 10
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2018, 37(10): 1477-1482.
doi: 10.13433/j.cnki.1003-8728.20180045
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Abstract:
In order to facilitate the kinematics analysis and optimization of the front wheel alignment parameters for Multi-link McPherson suspension, its kinematics analysis model is established based on the instant screw axis method, and the calculation method of the front wheel alignment parameters is proposed. It shows that the analysis model and calculation method are reliable verified by the ADAMS/Car suspension kinematics simulation. On this basis, taking partial suspension hard-point coordinates as the design variables and the minimum variation of the front wheel alignment parameters with the wheel beating and steering motions as the optimal target, multiobjective optimization of a certain hub motor electric vehicle suspension which has this type of suspension are carried out by NSGA-Ⅱalgorithm. Most of the front wheel alignment parameters optimized meet the design requirements and the suspension kinematics performance improved.
In order to facilitate the kinematics analysis and optimization of the front wheel alignment parameters for Multi-link McPherson suspension, its kinematics analysis model is established based on the instant screw axis method, and the calculation method of the front wheel alignment parameters is proposed. It shows that the analysis model and calculation method are reliable verified by the ADAMS/Car suspension kinematics simulation. On this basis, taking partial suspension hard-point coordinates as the design variables and the minimum variation of the front wheel alignment parameters with the wheel beating and steering motions as the optimal target, multiobjective optimization of a certain hub motor electric vehicle suspension which has this type of suspension are carried out by NSGA-Ⅱalgorithm. Most of the front wheel alignment parameters optimized meet the design requirements and the suspension kinematics performance improved.
2018, 37(10): 1483-1488.
doi: 10.13433/j.cnki.1003-8728.20180055
Abstract:
In order to solve the multi-robot coordination problem in dynamic environments, we propose a two-stage decoupled dynamic path modification method, which can coordinate multiple robots in offline mode. First, we present a multi-robot coordination framework. In the first stage of coordination, the A* algorithm is used to explore the collision-free path with respect to known static obstacles. In the second stage, the incremental A* algorithm is employed to find the collision-free and optimized path with respect to dynamic obstacles. Considering the planning time and path length, an evaluation model for dynamic path modification sequence is established for conflicting robots. The conflicts between robots are resolved through altering robot paths. A case study indicates that the proposed method is effective.
In order to solve the multi-robot coordination problem in dynamic environments, we propose a two-stage decoupled dynamic path modification method, which can coordinate multiple robots in offline mode. First, we present a multi-robot coordination framework. In the first stage of coordination, the A* algorithm is used to explore the collision-free path with respect to known static obstacles. In the second stage, the incremental A* algorithm is employed to find the collision-free and optimized path with respect to dynamic obstacles. Considering the planning time and path length, an evaluation model for dynamic path modification sequence is established for conflicting robots. The conflicts between robots are resolved through altering robot paths. A case study indicates that the proposed method is effective.
2018, 37(10): 1489-1495.
doi: 10.13433/j.cnki.1003-8728.20180071
Abstract:
This paper proposes a trajectory planning method for polishing the free-form surface of a robot so that the polishing robot may not have difficulty in planning its free-form surface and can improve its polishing accuracy. This method is based on the UG software environment to establish the free surface model. Based on the toolpath generation method for milling and polishing, the polishing trajectories are generated with the residual height algorithm. With the polishing trajectories generated, the Douglas-Peucker algorithm, which is used to extract the feature points of the polishing knife, is used to control the bow height error within a given range, improve the polishing accuracy and finally solve the robot's joint angle according to the data on continuous points of the polishing knife. The example shows that the polishing trajectory planning method has a high precision and can solve the free-form surface polishing trajectory planning problem.
This paper proposes a trajectory planning method for polishing the free-form surface of a robot so that the polishing robot may not have difficulty in planning its free-form surface and can improve its polishing accuracy. This method is based on the UG software environment to establish the free surface model. Based on the toolpath generation method for milling and polishing, the polishing trajectories are generated with the residual height algorithm. With the polishing trajectories generated, the Douglas-Peucker algorithm, which is used to extract the feature points of the polishing knife, is used to control the bow height error within a given range, improve the polishing accuracy and finally solve the robot's joint angle according to the data on continuous points of the polishing knife. The example shows that the polishing trajectory planning method has a high precision and can solve the free-form surface polishing trajectory planning problem.
2018, 37(10): 1496-1500.
doi: 10.13433/j.cnki.1003-8728.20180064
Abstract:
The Carsim software just focuses on modeling the traditional internal combustion engine car. This paper builds the dynamic model of a distributed drive electric vehicle based on the co-simulation of Carsim and Simulink. The Simulink motor model is connected to the co-simulation platform of the distributed driving electric vehicle after disconnecting the power source of the Carsim internal combustion engine model. Then the model was verified with the simulation. The co-simulation of double lane change and serpentine winding pile condition shows that both the Carsim model and the Simulink motor model have good response characteristics, thus providing an effective method for estimating the speed of the distributed drive electric vehicle.
The Carsim software just focuses on modeling the traditional internal combustion engine car. This paper builds the dynamic model of a distributed drive electric vehicle based on the co-simulation of Carsim and Simulink. The Simulink motor model is connected to the co-simulation platform of the distributed driving electric vehicle after disconnecting the power source of the Carsim internal combustion engine model. Then the model was verified with the simulation. The co-simulation of double lane change and serpentine winding pile condition shows that both the Carsim model and the Simulink motor model have good response characteristics, thus providing an effective method for estimating the speed of the distributed drive electric vehicle.
Research of Relation between Reacting Force and Center Displacement for Angular Contact Ball Bearing
2018, 37(10): 1501-1505.
doi: 10.13433/j.cnki.1003-8728.20180040
Abstract:
The 2-DOF pseudo-rigid-body model is applied, according to the mechanical and deformation characteristics of forced component in bearings. The contact force between the rolling bearing rings and the balls is obtained by force method in the given axial and radial displacement of bearing center. By this way the axial force, radial force and reacting torque of the bearing is also figured out. The influence of balls centrifugal force, gyroscopic moment, location of roller on force and deformation is also discussed. The results shows that:with the increasing of axial and radial deformation, the axial and radial reacting force increase significantly. At this time, the bearing can be considered as a nonlinear hard spring; the axial and radial reacting force will decrease due to the effect of centrifugal force and gyroscopic moment; the variation of reacting force and torque of bearing can be up to 1.92% as the change in the position of rolling.
The 2-DOF pseudo-rigid-body model is applied, according to the mechanical and deformation characteristics of forced component in bearings. The contact force between the rolling bearing rings and the balls is obtained by force method in the given axial and radial displacement of bearing center. By this way the axial force, radial force and reacting torque of the bearing is also figured out. The influence of balls centrifugal force, gyroscopic moment, location of roller on force and deformation is also discussed. The results shows that:with the increasing of axial and radial deformation, the axial and radial reacting force increase significantly. At this time, the bearing can be considered as a nonlinear hard spring; the axial and radial reacting force will decrease due to the effect of centrifugal force and gyroscopic moment; the variation of reacting force and torque of bearing can be up to 1.92% as the change in the position of rolling.
2018, 37(10): 1506-1511.
doi: 10.13433/j.cnki.1003-8728.20180058
Abstract:
In order to prevent rollover accidents and improve the lateral dynamic stability of the forklift under braking and steering conditions, the dynamic semi-model of forklift was built at first. Secondly the adaptive LQR control strategy is proposed in this paper, and the adaptive LQR controller of the active rear wheel steering system(ARS) is designed by the yaw rate and lateral acceleration as quadratic form indicators in order to overcome the time-varying position of mass center and uncertainties of dynamic behaviors caused by various forklift working conditions. The simulation was carried out in the braking and steering working conditions in MATLAB. The result of simulation shows that the lateral acceleration and yaw rate representing the lateral stability of forklifts are improved obviously in different working conditions and the lateral stability of forklift is also be enhanced significantly. The result of road test also shows that the root mean square values of the lateral acceleration and the yaw rate are reduced by 19.2% and 22.39% respectively, which improved the lateral dynamic stability of the counterbalanced forklift.
In order to prevent rollover accidents and improve the lateral dynamic stability of the forklift under braking and steering conditions, the dynamic semi-model of forklift was built at first. Secondly the adaptive LQR control strategy is proposed in this paper, and the adaptive LQR controller of the active rear wheel steering system(ARS) is designed by the yaw rate and lateral acceleration as quadratic form indicators in order to overcome the time-varying position of mass center and uncertainties of dynamic behaviors caused by various forklift working conditions. The simulation was carried out in the braking and steering working conditions in MATLAB. The result of simulation shows that the lateral acceleration and yaw rate representing the lateral stability of forklifts are improved obviously in different working conditions and the lateral stability of forklift is also be enhanced significantly. The result of road test also shows that the root mean square values of the lateral acceleration and the yaw rate are reduced by 19.2% and 22.39% respectively, which improved the lateral dynamic stability of the counterbalanced forklift.
2018, 37(10): 1512-1516.
doi: 10.13433/j.cnki.1003-8728.20180042
Abstract:
Surface roughness is a very important index in precision grinding of automotive engine crankshaft. On-line monitoring of surface roughness is a sign of intelligent grinding of the crankshaft. The PCI-2 acoustic emission experimental instrument made by PHYSICAL ACOUSTICS CORPORATION(PAC) was used in grinding test. By adopting a genetic algorithm for optimization of BP neural network and using grinding the acoustic emission signal root mean square(RMS) and fast Fourier transform peak as the characteristic values, the surface grinding crankshaft spheroidal graphite cast iron QT700-2 material surface roughness were predicted successfully. The relative error between the tested results and predicted is below 6.22%.
Surface roughness is a very important index in precision grinding of automotive engine crankshaft. On-line monitoring of surface roughness is a sign of intelligent grinding of the crankshaft. The PCI-2 acoustic emission experimental instrument made by PHYSICAL ACOUSTICS CORPORATION(PAC) was used in grinding test. By adopting a genetic algorithm for optimization of BP neural network and using grinding the acoustic emission signal root mean square(RMS) and fast Fourier transform peak as the characteristic values, the surface grinding crankshaft spheroidal graphite cast iron QT700-2 material surface roughness were predicted successfully. The relative error between the tested results and predicted is below 6.22%.
2018, 37(10): 1517-1522.
doi: 10.13433/j.cnki.1003-8728.20180043
Abstract:
In order to meet the special requirements for the remote and highly flexible actuation of a hydraulic device in a small area, a hydromechanical hybrid actuator with asymmetric double cylinders is proposed. Thin and long hoses connect miniature cylinders in this scheme. The motor drives the drag screw and thereby pushes the power-producing cylinder, which makes the pressure in the chamber of the actuating cylinder and its connecting hose increase until it moves. These constitute an asymmetric double cylinder drive. Both open loop and closed loop control systems are examined to decide a better system required. In order to obtain the desired steady and dynamic response, modeling and simulation are carried out, with the effects of the hose deformation taken into consideration. Results show that the hoses that connect miniature cylinders can prolong the response lag of the actuating cylinder and reduce the retract accuracy and the dynamic response. Developed from the absolutely symmetric double cylinder, the proposed asymmetric double cylinders with proper size ratio can improve the performance of the hydromechanical hybrid actuator but does not weaken its stability.
In order to meet the special requirements for the remote and highly flexible actuation of a hydraulic device in a small area, a hydromechanical hybrid actuator with asymmetric double cylinders is proposed. Thin and long hoses connect miniature cylinders in this scheme. The motor drives the drag screw and thereby pushes the power-producing cylinder, which makes the pressure in the chamber of the actuating cylinder and its connecting hose increase until it moves. These constitute an asymmetric double cylinder drive. Both open loop and closed loop control systems are examined to decide a better system required. In order to obtain the desired steady and dynamic response, modeling and simulation are carried out, with the effects of the hose deformation taken into consideration. Results show that the hoses that connect miniature cylinders can prolong the response lag of the actuating cylinder and reduce the retract accuracy and the dynamic response. Developed from the absolutely symmetric double cylinder, the proposed asymmetric double cylinders with proper size ratio can improve the performance of the hydromechanical hybrid actuator but does not weaken its stability.
2018, 37(10): 1523-1530.
doi: 10.13433/j.cnki.1003-8728.20180072
Abstract:
In order to study the dynamic effects of operating parameters (spindle speed, feed rate, cutting depth, etc.) on turning vibration, a method of testing and analyzing the vibration of sensitive point was proposed. Taking the numerical control turning process system of shaft parts as the research object, the complex working condition model was added to the digital prototype of the process system; then dynamic performance simulation test was carried out to determine the vibration sensitive points, the amplitude-frequency dynamic response would be recorded under different working conditions. The experimental results shown that the feed rate had the greatest influence on turning vibration relative to spindle speed and cutting depth, which was consistent with the numerical simulation results.
In order to study the dynamic effects of operating parameters (spindle speed, feed rate, cutting depth, etc.) on turning vibration, a method of testing and analyzing the vibration of sensitive point was proposed. Taking the numerical control turning process system of shaft parts as the research object, the complex working condition model was added to the digital prototype of the process system; then dynamic performance simulation test was carried out to determine the vibration sensitive points, the amplitude-frequency dynamic response would be recorded under different working conditions. The experimental results shown that the feed rate had the greatest influence on turning vibration relative to spindle speed and cutting depth, which was consistent with the numerical simulation results.
2018, 37(10): 1531-1536.
doi: 10.13433/j.cnki.1003-8728.20180061
Abstract:
In order to solve the problems in high aspect ratio micro channel machining, a novel process of template shielded wire electrochemical machining (TSWECM) is presented. A novel special fixture was designed to restrict distribution of electric field and increase electrolyte flow rate in machining zone, then the removal of electrolytic products strengthened, the machining accuracy and process efficiency enhanced. The effects of the notch width on the machining were studied by using the simulation and experiment. The results show that under the notch width of template below 1 mm, the machining accuracy of micro channel increased. The micro channel with a width of 981 μm and depth of 1 058 μm was successfully fabricated on the stainless steel surface by using the presented TSWECM process, in which a notch width of shielding template of 1 mm and diameter of wire cathode of 0.3 mm were utilized.
In order to solve the problems in high aspect ratio micro channel machining, a novel process of template shielded wire electrochemical machining (TSWECM) is presented. A novel special fixture was designed to restrict distribution of electric field and increase electrolyte flow rate in machining zone, then the removal of electrolytic products strengthened, the machining accuracy and process efficiency enhanced. The effects of the notch width on the machining were studied by using the simulation and experiment. The results show that under the notch width of template below 1 mm, the machining accuracy of micro channel increased. The micro channel with a width of 981 μm and depth of 1 058 μm was successfully fabricated on the stainless steel surface by using the presented TSWECM process, in which a notch width of shielding template of 1 mm and diameter of wire cathode of 0.3 mm were utilized.
2018, 37(10): 1537-1543.
doi: 10.13433/j.cnki.1003-8728.20180060
Abstract:
For better use of low-grade heat, the structure of two kinds of impeller, 90° IFR and IFG, of the radial inflow turbine suitable for organic Rankine cycle system (ORC) of low-temperature geothermal power was self-designed and developed. And the numerical simulation is carried out. The results show that under diverse working conditions for the same inlet pressure and temperature, the same outlet pressure and the same flow rate, comparing with the turbine with 90°IFR, the turbine with IFG has higher efficiency. In order to further improve the efficiency of two radial inflow turbines, the impeller of two radial inflow turbines has been optimized by using the uniform test. And the one-way fluid solid coupling method is used to check the strength of the optimized impeller blade. The results show that the maximum isentropic efficiency is 86.9% and 87.9%, increased by 1.9% and 1.4% respectively. After optimization, the flow in the impeller is improved and the performance of impeller is enhanced. The strength check results show that the strength of the impeller blades of the maximum deformation of the optimized design was less than the tip clearance, and the maximum equivalent stress is far less than the yield strength of the material. The impeller meets the requirements of safe operation.
For better use of low-grade heat, the structure of two kinds of impeller, 90° IFR and IFG, of the radial inflow turbine suitable for organic Rankine cycle system (ORC) of low-temperature geothermal power was self-designed and developed. And the numerical simulation is carried out. The results show that under diverse working conditions for the same inlet pressure and temperature, the same outlet pressure and the same flow rate, comparing with the turbine with 90°IFR, the turbine with IFG has higher efficiency. In order to further improve the efficiency of two radial inflow turbines, the impeller of two radial inflow turbines has been optimized by using the uniform test. And the one-way fluid solid coupling method is used to check the strength of the optimized impeller blade. The results show that the maximum isentropic efficiency is 86.9% and 87.9%, increased by 1.9% and 1.4% respectively. After optimization, the flow in the impeller is improved and the performance of impeller is enhanced. The strength check results show that the strength of the impeller blades of the maximum deformation of the optimized design was less than the tip clearance, and the maximum equivalent stress is far less than the yield strength of the material. The impeller meets the requirements of safe operation.
2018, 37(10): 1544-1550.
doi: 10.13433/j.cnki.1003-8728.20180018
Abstract:
The cutting efficiency and the surface roughness of the monocrystalline silicon are two important indexes which are tradeoff in the production for wire-cut electrical discharge machining (WEDM), and it is hoped to improve the cutting efficiency of monocrystalline silicon while ensuring the surface quality of the work-piece. This paper develops the objective function of the cutting efficiency and surface roughness of monocrystalline silicon WEDM by using the response surface methodology (RSM). A set of Pareto optimal solutions for cutting efficiency and surface roughness are obtained by improved strength Pareto evolutionary algorithm (SPEA-Ⅱ). The Pareto optimal solution obtained by SPEA-Ⅱ is compared with the solution obtained by improving the non-dominated sorting genetic algorithm (NSGA-Ⅱ) under the same conditions. The optimization performance of the two algorithms for objective function is tested.
The cutting efficiency and the surface roughness of the monocrystalline silicon are two important indexes which are tradeoff in the production for wire-cut electrical discharge machining (WEDM), and it is hoped to improve the cutting efficiency of monocrystalline silicon while ensuring the surface quality of the work-piece. This paper develops the objective function of the cutting efficiency and surface roughness of monocrystalline silicon WEDM by using the response surface methodology (RSM). A set of Pareto optimal solutions for cutting efficiency and surface roughness are obtained by improved strength Pareto evolutionary algorithm (SPEA-Ⅱ). The Pareto optimal solution obtained by SPEA-Ⅱ is compared with the solution obtained by improving the non-dominated sorting genetic algorithm (NSGA-Ⅱ) under the same conditions. The optimization performance of the two algorithms for objective function is tested.
2018, 37(10): 1551-1558.
doi: 10.13433/j.cnki.1003-8728.20180078
Abstract:
To study the influence of the cutting parameters and geometric parameters of the cutting tool on the drilling quality, simulation of drilling Carbon Fiber Reinforced Plastic (CFRP) composites was conducted by using software ABAQUS. A model for predicting the thrust force in drilling was established based on the Response Surface Methodology (RSM), in which the spindle speed, feed rate, and point angle were considered as the design variables. The influence of those variables on the thrust force was analyzed as well. The results show that the thrust force decreases with the increasing of spindle speed, and increases with the increasing of feed rate and point angle. The order of influencing significance on the thrust force is the feed rate, spindle speed, and point angle. The prediction model has high confidence. It is recommended to use higher spindle speed, smaller feed and point angle in drilling, in order to reduce the thrust force and improve the drilling quality of CFRP composites.
To study the influence of the cutting parameters and geometric parameters of the cutting tool on the drilling quality, simulation of drilling Carbon Fiber Reinforced Plastic (CFRP) composites was conducted by using software ABAQUS. A model for predicting the thrust force in drilling was established based on the Response Surface Methodology (RSM), in which the spindle speed, feed rate, and point angle were considered as the design variables. The influence of those variables on the thrust force was analyzed as well. The results show that the thrust force decreases with the increasing of spindle speed, and increases with the increasing of feed rate and point angle. The order of influencing significance on the thrust force is the feed rate, spindle speed, and point angle. The prediction model has high confidence. It is recommended to use higher spindle speed, smaller feed and point angle in drilling, in order to reduce the thrust force and improve the drilling quality of CFRP composites.
2018, 37(10): 1559-1565.
doi: 10.13433/j.cnki.1003-8728.20180056
Abstract:
Ultrasonic guided-wave (UGW) is an emerging non-destructive testing technique in recent years. Compared with the conventional inspection techniques, such as ultrasonic inspection and magnetic flux leakage testing, the UGW can enable long-range, comprehensive and efficient inspection. It thus attracts more attention, especially for pipe inspection. However, the propagation and reflection of guided wave are complicated, and it is always essential to introduce finite element analysis (FEA) into UGW research for guidance and verification of experimental results. How to guarantee the accuracy of FEA model is an important problem. In this paper, with number of time substeps as an example, the effects of simulation parameters on simulation models are analyzed, and the method for selecting the optimal simulation parameters with quantitative evaluation criteria is proposed. The comparison results between simulation and experimental results verify that the method is effective for optimizing simulation parameters.
Ultrasonic guided-wave (UGW) is an emerging non-destructive testing technique in recent years. Compared with the conventional inspection techniques, such as ultrasonic inspection and magnetic flux leakage testing, the UGW can enable long-range, comprehensive and efficient inspection. It thus attracts more attention, especially for pipe inspection. However, the propagation and reflection of guided wave are complicated, and it is always essential to introduce finite element analysis (FEA) into UGW research for guidance and verification of experimental results. How to guarantee the accuracy of FEA model is an important problem. In this paper, with number of time substeps as an example, the effects of simulation parameters on simulation models are analyzed, and the method for selecting the optimal simulation parameters with quantitative evaluation criteria is proposed. The comparison results between simulation and experimental results verify that the method is effective for optimizing simulation parameters.
2018, 37(10): 1566-1572.
doi: 10.13433/j.cnki.1003-8728.20180036
Abstract:
The supervised learning is commonly adopted in fault feature extraction for mechanical equipment fault diagnosis, while the labeled data are often hard to obtain. To deal with such problem, a deep neural network embedding convolution networks in sparse encoder is proposed. The transformations of Hilbert and Fourier make it possible to transform the vibration time series of machinery into Hilbert envelope spectrum. Different features of spectral space data are automatically learned with multiple sets of convolution kernels in convolution networks, which ensure the automation, comprehensiveness and diversity of the extracted features. The sparse encoder looks for a low-dimensional representation of data featured with orthogonality, making the encoded data characterized by strong clustering; so that the automatic fault diagnosis of the equipment is realized. Through analysis and experiments on vibration signals of rolling bearings, it is proved that this method has the characteristics of de-labeling, automation and robustness in equipment fault diagnosis.
The supervised learning is commonly adopted in fault feature extraction for mechanical equipment fault diagnosis, while the labeled data are often hard to obtain. To deal with such problem, a deep neural network embedding convolution networks in sparse encoder is proposed. The transformations of Hilbert and Fourier make it possible to transform the vibration time series of machinery into Hilbert envelope spectrum. Different features of spectral space data are automatically learned with multiple sets of convolution kernels in convolution networks, which ensure the automation, comprehensiveness and diversity of the extracted features. The sparse encoder looks for a low-dimensional representation of data featured with orthogonality, making the encoded data characterized by strong clustering; so that the automatic fault diagnosis of the equipment is realized. Through analysis and experiments on vibration signals of rolling bearings, it is proved that this method has the characteristics of de-labeling, automation and robustness in equipment fault diagnosis.
2018, 37(10): 1573-1580.
doi: 10.13433/j.cnki.1003-8728.20180050
Abstract:
Base on filtered Poisson road model, considering unsteady factor of random velocity variation, an improved filtered Poisson road model and fatigue load calculation method under the excitation of the model are presented for automobile fatigue load analysis. Taking 1/4 vehicle model as the researching object and improved filtered Poisson road model as excitation, the amplitude-frequency characteristics and statistical counting characteristics of load response of sprung mass and unsprung mass are calculated under two conditions of steady and unsteady excitation of constant velocity and random variation of velocity subordinating uniform distribution. The statistical date of response load under different velocity and distribution parameter of velocity is analyzed and compared. The result shows that the improved filtered Poisson road model can be used for fatigue load calculation of automobiles, and it can realize load response calculation under unsteady road excitation when velocity is random variation.
Base on filtered Poisson road model, considering unsteady factor of random velocity variation, an improved filtered Poisson road model and fatigue load calculation method under the excitation of the model are presented for automobile fatigue load analysis. Taking 1/4 vehicle model as the researching object and improved filtered Poisson road model as excitation, the amplitude-frequency characteristics and statistical counting characteristics of load response of sprung mass and unsprung mass are calculated under two conditions of steady and unsteady excitation of constant velocity and random variation of velocity subordinating uniform distribution. The statistical date of response load under different velocity and distribution parameter of velocity is analyzed and compared. The result shows that the improved filtered Poisson road model can be used for fatigue load calculation of automobiles, and it can realize load response calculation under unsteady road excitation when velocity is random variation.
2018, 37(10): 1581-1588.
doi: 10.13433/j.cnki.1003-8728.20180046
Abstract:
Considering stochastic cases of load values and directions, a robust structural topology optimization method for weighted sum minimizing problem of the expected value of the compliance and its variance with a volume constraint and multiple displacement constraints is proposed to obtain a clear optimal topology. Firstly, the explicit approximate expressions of the compliance expected value, its variance and their derivatives are derived. Secondly, the set of algorithms for robust structural topology optimization designs with multiple constraints are given, being integrated with an feasible domain adjustment scheme. The effects of the weighted coefficients of the expected value and variance of the compliance on the optimized solutions, and the effects of the multiple displacement constraints on the robustness of the optimal topology are investigated. The simulation examples show that the present method is feasible and effective, and can be adopted to obtain a series of clear topology configurations and a robust optimal topology.
Considering stochastic cases of load values and directions, a robust structural topology optimization method for weighted sum minimizing problem of the expected value of the compliance and its variance with a volume constraint and multiple displacement constraints is proposed to obtain a clear optimal topology. Firstly, the explicit approximate expressions of the compliance expected value, its variance and their derivatives are derived. Secondly, the set of algorithms for robust structural topology optimization designs with multiple constraints are given, being integrated with an feasible domain adjustment scheme. The effects of the weighted coefficients of the expected value and variance of the compliance on the optimized solutions, and the effects of the multiple displacement constraints on the robustness of the optimal topology are investigated. The simulation examples show that the present method is feasible and effective, and can be adopted to obtain a series of clear topology configurations and a robust optimal topology.
2018, 37(10): 1589-1595.
doi: 10.13433/j.cnki.1003-8728.20180053
Abstract:
To reveal temperature field of disc brake caliper unit and influence of geometric structures of brake pad, a full model for high-speed train disc brake caliper unit is established and finite element analysis of transient temperature field is carried out. By applying heat flux on friction surfaces in ANSYS simulation, four designation of brake pad structures (pad with or without hole and washer) were simulated at the same setup conditions; followed by throughout comparison and discussion for the temperature field results, thermal stress of some caliper components been reviewed in details. Analysis of thermal stress indicated that the pad plate was vulnerable to thermal fatigue and the pad holder was at the margin of thermal fatigue.
To reveal temperature field of disc brake caliper unit and influence of geometric structures of brake pad, a full model for high-speed train disc brake caliper unit is established and finite element analysis of transient temperature field is carried out. By applying heat flux on friction surfaces in ANSYS simulation, four designation of brake pad structures (pad with or without hole and washer) were simulated at the same setup conditions; followed by throughout comparison and discussion for the temperature field results, thermal stress of some caliper components been reviewed in details. Analysis of thermal stress indicated that the pad plate was vulnerable to thermal fatigue and the pad holder was at the margin of thermal fatigue.
2018, 37(10): 1596-1602.
doi: 10.13433/j.cnki.1003-8728.20180180
Abstract:
Taking the battery module of an electric vehicle with bus-bar as the research object, the effects of the design parameters such as the electric-discharge magnification, the bus-bar contact area and the current I/O position on the electric field and the temperature field of module are studied. Based on the analysis of the temperature field distribution, the influence in the battery monomer and the bus-bar of the design parameters on the temperature change, the uniformity of the temperature and the heat exchange between the two groups were investigated. The results show that the current discharge magnification not only affects the temperature rise, but also the heat exchange between the bus-bar and the cell. Therefore, the heat of the bus-bar on the effect of a cell should be taken into account in the high current charge-discharge conditions. The contact area and position of current I/O will have different effects on battery temperature rise, temperature balance and current balance.
Taking the battery module of an electric vehicle with bus-bar as the research object, the effects of the design parameters such as the electric-discharge magnification, the bus-bar contact area and the current I/O position on the electric field and the temperature field of module are studied. Based on the analysis of the temperature field distribution, the influence in the battery monomer and the bus-bar of the design parameters on the temperature change, the uniformity of the temperature and the heat exchange between the two groups were investigated. The results show that the current discharge magnification not only affects the temperature rise, but also the heat exchange between the bus-bar and the cell. Therefore, the heat of the bus-bar on the effect of a cell should be taken into account in the high current charge-discharge conditions. The contact area and position of current I/O will have different effects on battery temperature rise, temperature balance and current balance.
2018, 37(10): 1603-1610.
doi: 10.13433/j.cnki.1003-8728.20180062
Abstract:
Based on the different damage theory, the intelligent algorithm, which can predict the fatigue life of crane metal structure via artificial intelligence technology has become a new hot point in the crane field. In practice, some intelligent algorithms are often used to solve some complex nonlinear problems. Therefore, the neural network algorithm and the support vector machine algorithm are used to simulate the experiment, and the fatigue life under the two stage load is estimated, respectively. According to the experimental data given by predecessors, the fatigue simulation of normalizing No. 35 steel and the quenched and tempered No. 45 steel is carried out by using the neural network and genetic algorithm and the support vector machine algorithm based on the particle swarm optimization, respectively. Besides, the nonlinear relationship between the stress and cumulative damage and the influence of stress loading sequence on the fatigue life are described. The fatigue parameters of the most common welded pipe joints in offshore platforms are predicted to verify the practicability of the optimized intelligent algorithm. At the same time, the results are compared with the optimized BP neural network and support vector machine to verify. The optimization method has the great effect on the improvement of the prediction precision of the intelligent algorithm.
Based on the different damage theory, the intelligent algorithm, which can predict the fatigue life of crane metal structure via artificial intelligence technology has become a new hot point in the crane field. In practice, some intelligent algorithms are often used to solve some complex nonlinear problems. Therefore, the neural network algorithm and the support vector machine algorithm are used to simulate the experiment, and the fatigue life under the two stage load is estimated, respectively. According to the experimental data given by predecessors, the fatigue simulation of normalizing No. 35 steel and the quenched and tempered No. 45 steel is carried out by using the neural network and genetic algorithm and the support vector machine algorithm based on the particle swarm optimization, respectively. Besides, the nonlinear relationship between the stress and cumulative damage and the influence of stress loading sequence on the fatigue life are described. The fatigue parameters of the most common welded pipe joints in offshore platforms are predicted to verify the practicability of the optimized intelligent algorithm. At the same time, the results are compared with the optimized BP neural network and support vector machine to verify. The optimization method has the great effect on the improvement of the prediction precision of the intelligent algorithm.
2018, 37(10): 1611-1617.
doi: 10.13433/j.cnki.1003-8728.20180066
Abstract:
Scarf bonded joint is one of the main forms of composite joint, the failure modes of composite scarf bonded joint are complex, including composite laminates failure and adhesive layer failure. An computer simulation method for composite scarf joint failure analysis and strength prediction was proposed by introducing two failure models, as cohesive zone model used for simulating adhesive layer, and progressive damage model based on the three dimension Hashin failure criterion and the exponential stiffness degradation criterion for simulating the composite laminates failure. Based on the nonlinear analysis method, a finite element model for predicting adhesive failure and composite laminate failure was established. The structural analysis model was verified by the testing data, and the failure modes were analyzed by using the present model. The influences of the scarf angle and adhesive fracture toughness on the joint strength were studied, and the influence laws were obtained.
Scarf bonded joint is one of the main forms of composite joint, the failure modes of composite scarf bonded joint are complex, including composite laminates failure and adhesive layer failure. An computer simulation method for composite scarf joint failure analysis and strength prediction was proposed by introducing two failure models, as cohesive zone model used for simulating adhesive layer, and progressive damage model based on the three dimension Hashin failure criterion and the exponential stiffness degradation criterion for simulating the composite laminates failure. Based on the nonlinear analysis method, a finite element model for predicting adhesive failure and composite laminate failure was established. The structural analysis model was verified by the testing data, and the failure modes were analyzed by using the present model. The influences of the scarf angle and adhesive fracture toughness on the joint strength were studied, and the influence laws were obtained.
2018, 37(10): 1618-1623.
doi: 10.13433/j.cnki.1003-8728.20180165
Abstract:
Development of complex equipment include complex process, huge-and-complex data and multidisciplinary scattered analysis method. The design of the complex equipment is a creative process of a multi cycle iterative optimization, in which requires a lot of reference expert knowledge system, design experience and data resources. Aiming at the above-mentioned problems and requirement, based on the theory and key technology of intelligent design, a digital design plan and implementation method of complex equipment was proposed in order to meet the construction of software for the intelligent design of complex equipment. In the end, the practical description for the cases of aviation industry were made. The quality of the design and analysis has been greatly improved.
Development of complex equipment include complex process, huge-and-complex data and multidisciplinary scattered analysis method. The design of the complex equipment is a creative process of a multi cycle iterative optimization, in which requires a lot of reference expert knowledge system, design experience and data resources. Aiming at the above-mentioned problems and requirement, based on the theory and key technology of intelligent design, a digital design plan and implementation method of complex equipment was proposed in order to meet the construction of software for the intelligent design of complex equipment. In the end, the practical description for the cases of aviation industry were made. The quality of the design and analysis has been greatly improved.
2018, 37(10): 1624-1627.
doi: 10.13433/j.cnki.1003-8728.20180176
Abstract:
Flutter characteristic analysis for the aeroelastic system with large control surface deflection at the trailing edge of a wing is studied, where airflow separation may occur. Computational fluid dynamics (CFD) technique is adopted to obtain the aerodynamic forces on the control surface with large deflection, then the aerodynamic forces obtained by doublet lattice method (DLM) are corrected by using these data from CFD, and finally wing flutter characteristics are obtained. Aerodynamic force corrections on control surface show no effect on the calculated flutter type of the aeroelastic system for the present model, in which the flutter type obtained with and without control surface aerodynamic correction is coupled flutter from both wing bending and outboard control surface deflection. The flutter speed obtained with aerodynamic correction is higher for the present model.
Flutter characteristic analysis for the aeroelastic system with large control surface deflection at the trailing edge of a wing is studied, where airflow separation may occur. Computational fluid dynamics (CFD) technique is adopted to obtain the aerodynamic forces on the control surface with large deflection, then the aerodynamic forces obtained by doublet lattice method (DLM) are corrected by using these data from CFD, and finally wing flutter characteristics are obtained. Aerodynamic force corrections on control surface show no effect on the calculated flutter type of the aeroelastic system for the present model, in which the flutter type obtained with and without control surface aerodynamic correction is coupled flutter from both wing bending and outboard control surface deflection. The flutter speed obtained with aerodynamic correction is higher for the present model.
2018, 37(10): 1628-1633.
doi: 10.13433/j.cnki.1003-8728.20180059
Abstract:
To improve the fault diagnosis efficiency of helicopter gearbox, the information entropy and ABC-BP neural network are adopted in this paper. Combining wavelet packet and information entropy, the wavelet packet entropy of vibration signal of gearbox is extracted as the characteristic input vector of neural network, then the BP neural network is used for pattern recognition and fault classification of the characteristic parameters of gearbox, and artificial bee colony (ABC) is introduced in the optimization of BP neural network. The error function of BP neural network as the artificial bee colony fitness, individual parameters of optimal fitness degree are choose as the weights and thresholds of neural network. This method not only reduces the model input dimension, but also improves the diagnostic accuracy. Finally, the experimental results show that the diagnosis model has good effect.
To improve the fault diagnosis efficiency of helicopter gearbox, the information entropy and ABC-BP neural network are adopted in this paper. Combining wavelet packet and information entropy, the wavelet packet entropy of vibration signal of gearbox is extracted as the characteristic input vector of neural network, then the BP neural network is used for pattern recognition and fault classification of the characteristic parameters of gearbox, and artificial bee colony (ABC) is introduced in the optimization of BP neural network. The error function of BP neural network as the artificial bee colony fitness, individual parameters of optimal fitness degree are choose as the weights and thresholds of neural network. This method not only reduces the model input dimension, but also improves the diagnostic accuracy. Finally, the experimental results show that the diagnosis model has good effect.
2018, 37(10): 1634-1640.
doi: 10.13433/j.cnki.1003-8728.20180049
Abstract:
Half-rotating wing (HRW) is a new flapping-imitating wing system with rotating-type flapping instead of oscillating-type flapping. The working principle of HRW was firstly introduced in this paper. The design scheme of lift testing device and lift computational model were then given to explore the aerodynamic characteristics of HRW in hovering flight. The aerodynamic experiment was performed by two wing layout with different wing material. The experiment results showed that:the flow field generated by the motion of the wing arranged symmetry in body would interfere with each other, by which the average lift coefficient of the double-wing HRW was less than that of the single-wing HRW;on the other hand, the average lift coefficient of flexible wing was larger than that of the rigid wing;in addition, the average lift of the flexible wing would go up with the increasing of degree of relaxation when it was within the appropriate range. Above research results revealed the aerodynamic characteristics of HRW in hovering flight.
Half-rotating wing (HRW) is a new flapping-imitating wing system with rotating-type flapping instead of oscillating-type flapping. The working principle of HRW was firstly introduced in this paper. The design scheme of lift testing device and lift computational model were then given to explore the aerodynamic characteristics of HRW in hovering flight. The aerodynamic experiment was performed by two wing layout with different wing material. The experiment results showed that:the flow field generated by the motion of the wing arranged symmetry in body would interfere with each other, by which the average lift coefficient of the double-wing HRW was less than that of the single-wing HRW;on the other hand, the average lift coefficient of flexible wing was larger than that of the rigid wing;in addition, the average lift of the flexible wing would go up with the increasing of degree of relaxation when it was within the appropriate range. Above research results revealed the aerodynamic characteristics of HRW in hovering flight.
