Author Center
Editor Work
Peer Review
Editorial Entry
Email Alert
RSS2015 Vol. 34, No. 11
Display Method:
2015, 34(11): 1641-1647.
doi: 10.13433/j.cnki.1003-8728.2015.1101
PDF 1099KB
Abstract:
For the structure and the serviceing condition of a fluid hydrophilic finger seals, a finger seal structure(referred to as combination finger seal)which has the combination of circumferential convergent boots and on a herringbone-Grooved rotor was established. Using the fluid-solid coupling numerical analysis method, the seal leakage rate, the gas film bearing capacity and gas film flow field characteristics of the combination finger seal under the different structure and the serviceing condition was analyzed. And the effects of seal structure parameters on the combination finger sealing performance are discussed in detail. The results show that under the normal operating range, the impact that pressure flow acting on the sealing performance of the combination finger seal has absolute predominance. The thickness ratio and radial minimum thickness of wedge gas film make the maximum influence on the seal leakage rate. The distance herringbone groove deviating from the high-pressure plate, longitudinal spacing and width of the groove have obvious impact on the performance of combination finger seal. Comparing with the performance of circumferential convergent hydrodynamic finger seal and finger seal on a herringbone-grooved rotor, the bearing capacity of gas film of the combination finger seal is apparently higher than it in the finger seal on a herringbone-grooved rotor. The leakage rate of the combination finger seal and the finger seal of circumferential convergent roots make no distinction of rank, but the film bearing capacity of combination finger seal is bigger. The further study shows that the combination finger seal has the comprehensive advantages.
For the structure and the serviceing condition of a fluid hydrophilic finger seals, a finger seal structure(referred to as combination finger seal)which has the combination of circumferential convergent boots and on a herringbone-Grooved rotor was established. Using the fluid-solid coupling numerical analysis method, the seal leakage rate, the gas film bearing capacity and gas film flow field characteristics of the combination finger seal under the different structure and the serviceing condition was analyzed. And the effects of seal structure parameters on the combination finger sealing performance are discussed in detail. The results show that under the normal operating range, the impact that pressure flow acting on the sealing performance of the combination finger seal has absolute predominance. The thickness ratio and radial minimum thickness of wedge gas film make the maximum influence on the seal leakage rate. The distance herringbone groove deviating from the high-pressure plate, longitudinal spacing and width of the groove have obvious impact on the performance of combination finger seal. Comparing with the performance of circumferential convergent hydrodynamic finger seal and finger seal on a herringbone-grooved rotor, the bearing capacity of gas film of the combination finger seal is apparently higher than it in the finger seal on a herringbone-grooved rotor. The leakage rate of the combination finger seal and the finger seal of circumferential convergent roots make no distinction of rank, but the film bearing capacity of combination finger seal is bigger. The further study shows that the combination finger seal has the comprehensive advantages.
2015, 34(11): 1648-1652.
doi: 10.13433/j.cnki.1003-8728.2015.1102
Abstract:
To promote the development of renewable ocean energy sources and to utilization and improve the efficiency of capture mechanism, the number of turbines and composition of body mechanics is studied based on the simulation of the turbulence flow organization with computational fluid dynamics (CFD) via RNG K-ε, and the finite element meshing method of the mechanism is presented. Based on the above-mentioned dicussion, the turbine characteristics are studied under different angles of attack and the state of the flow field is studied; finally the best angle of attack range is presented.
To promote the development of renewable ocean energy sources and to utilization and improve the efficiency of capture mechanism, the number of turbines and composition of body mechanics is studied based on the simulation of the turbulence flow organization with computational fluid dynamics (CFD) via RNG K-ε, and the finite element meshing method of the mechanism is presented. Based on the above-mentioned dicussion, the turbine characteristics are studied under different angles of attack and the state of the flow field is studied; finally the best angle of attack range is presented.
2015, 34(11): 1653-1658.
doi: 10.13433/j.cnki.1003-8728.2015.1103
Abstract:
To fulfill users' perceptual demand and reduce the cognition difference of product form between the users and the designers, user demand model was studied and design constraint space was constructed. Through Interactive Genetic Algorithms, both users and designers were allowed to participate in seeking optimal solutions. To reduce fatigue in interactive evaluation process, neural network was used to simulate users' and designers' evaluation intent for automotive solution of product form which would meet users' needs and designers' design intent simultaneously. The family car face design was taken as an example to verify the effectiveness of the proposed method.
To fulfill users' perceptual demand and reduce the cognition difference of product form between the users and the designers, user demand model was studied and design constraint space was constructed. Through Interactive Genetic Algorithms, both users and designers were allowed to participate in seeking optimal solutions. To reduce fatigue in interactive evaluation process, neural network was used to simulate users' and designers' evaluation intent for automotive solution of product form which would meet users' needs and designers' design intent simultaneously. The family car face design was taken as an example to verify the effectiveness of the proposed method.
2015, 34(11): 1659-1663.
doi: 10.13433/j.cnki.1003-8728.2015.1104
Abstract:
The fundamental and analysis process of the operational transfer path analysis method are clearly illustrated firstly; based on the single path isolation system, the transfer function of transfer path is calculated and its accuracy is analyzed; At last, the vibration transmission capacity of each path of a three-paths isolation system is analyzed by OTPA method, the critical path of vibration transmission is determined using contribution analysis of vibration transmission. The method and process of analysis can provide the research foundation for vibration or noise source localization, transfer mechanism analysis, and vibration or noise control.
The fundamental and analysis process of the operational transfer path analysis method are clearly illustrated firstly; based on the single path isolation system, the transfer function of transfer path is calculated and its accuracy is analyzed; At last, the vibration transmission capacity of each path of a three-paths isolation system is analyzed by OTPA method, the critical path of vibration transmission is determined using contribution analysis of vibration transmission. The method and process of analysis can provide the research foundation for vibration or noise source localization, transfer mechanism analysis, and vibration or noise control.
2015, 34(11): 1664-1669.
doi: 10.13433/j.cnki.1003-8728.2015.1105
Abstract:
A new kind of scribing device for parallel mechanism was put forward. The comprehensive position error models of the scribing head were established and analyzed. The Comprehensive position error model was established with the kinematics equation differential method and the position error model of the scribing head under the influence of each independent factor was established with the error independent principle method. Monte-Carlo method was used to simulate and analyze these two kinds of error models. The results showed that overall comprehensive error range of the position error model of the scribing device is 0~7.5×10-3 mm, and the position error model of the scribing head is 0~4×10-4 mm when only considering the influence of length error, 6×10-5 mm~9.5×10-5 mm when only considering the influence of rotation clearance error. It can be seen that the scribing comprehensive position error is influenced by multiple factors, especially driving rod length error largely, and comprehensive position error is not a simple superposition of each factor. This error analysis method, combining the two error modeling methods, can be comprehensively and systematically used to analyze comprehensive position error of the device's scribing head.
A new kind of scribing device for parallel mechanism was put forward. The comprehensive position error models of the scribing head were established and analyzed. The Comprehensive position error model was established with the kinematics equation differential method and the position error model of the scribing head under the influence of each independent factor was established with the error independent principle method. Monte-Carlo method was used to simulate and analyze these two kinds of error models. The results showed that overall comprehensive error range of the position error model of the scribing device is 0~7.5×10-3 mm, and the position error model of the scribing head is 0~4×10-4 mm when only considering the influence of length error, 6×10-5 mm~9.5×10-5 mm when only considering the influence of rotation clearance error. It can be seen that the scribing comprehensive position error is influenced by multiple factors, especially driving rod length error largely, and comprehensive position error is not a simple superposition of each factor. This error analysis method, combining the two error modeling methods, can be comprehensively and systematically used to analyze comprehensive position error of the device's scribing head.
2015, 34(11): 1670-1674.
doi: 10.13433/j.cnki.1003-8728.2015.1106
Abstract:
To find out the characteristics of a spray painting robot when a large curvature surface is sprayed, we set up its mathematical expression model based on the characteristics of the large curvature surface. Then the large curvature surface is divided into a number of combinations. We optimize the trajectory of the spray gun by setting up its optimization objective function. We use the idea of particle swarm optimization algorithm to solve the problem of patch trajectory combination, which is caused by shading. The use of algorithm improves the efficiency and accuracy of the spray painting robot for the big curvature surface.
To find out the characteristics of a spray painting robot when a large curvature surface is sprayed, we set up its mathematical expression model based on the characteristics of the large curvature surface. Then the large curvature surface is divided into a number of combinations. We optimize the trajectory of the spray gun by setting up its optimization objective function. We use the idea of particle swarm optimization algorithm to solve the problem of patch trajectory combination, which is caused by shading. The use of algorithm improves the efficiency and accuracy of the spray painting robot for the big curvature surface.
2015, 34(11): 1675-1681.
doi: 10.13433/j.cnki.1003-8728.2015.1107
Abstract:
A location system of indoor robot based on the monocular camera is presented, in which the double balls of constant distance is used as labels in this system. Firstly, the software design is developed via Open Source Computer Vision Library 2.4.4(OpenCV2.4.4) and Visual Studio 2010(VS2010) platform, including the identification of double balls of constant distance and the measurement of location and direction. Then, the hardware design about the communication and control of indoor robot is finished by using nRF24L01 chip and STM8S105 chip. The experimental results show that the application of double balls of constant distance has the advantages in low cost, simple structure, stability and high location accuracy, and the positioning of location and direction is simultaneously accomplished. Generally the relative error of positioning is about 1.5%, and the absolute error of a short distance positioning in the range of 3 m is less than 1 cm. It is suitable for the occasion for high requirement of location accuracy about indoor robot in industry.
A location system of indoor robot based on the monocular camera is presented, in which the double balls of constant distance is used as labels in this system. Firstly, the software design is developed via Open Source Computer Vision Library 2.4.4(OpenCV2.4.4) and Visual Studio 2010(VS2010) platform, including the identification of double balls of constant distance and the measurement of location and direction. Then, the hardware design about the communication and control of indoor robot is finished by using nRF24L01 chip and STM8S105 chip. The experimental results show that the application of double balls of constant distance has the advantages in low cost, simple structure, stability and high location accuracy, and the positioning of location and direction is simultaneously accomplished. Generally the relative error of positioning is about 1.5%, and the absolute error of a short distance positioning in the range of 3 m is less than 1 cm. It is suitable for the occasion for high requirement of location accuracy about indoor robot in industry.
2015, 34(11): 1682-1685.
doi: 10.13433/j.cnki.1003-8728.2015.1108
Abstract:
In order to solve the yielding failure problem of water jet energy accumulator barrel due to high pressure, the prestressed composite structure design and the theory of equal strength are used to determine the parameters of accumulator barrel, such as the internal cylinder of the composite cylinder, the radii of the inner and outer cylinders, the radius of sub-layer and the optimal interference. Then the ANSYS software is used to analyze the cylinder model with the finite element method, the equivalent stress of the effective node along the wall thickness of the simulation model is obtained by path extraction method and the distribution curves of the equivalent stress along the wall thickness with different internal pressure are also obtained. By analyzing the simulated results and curves, the design parameters of accumulator barrel meet the expected strength requirement.
In order to solve the yielding failure problem of water jet energy accumulator barrel due to high pressure, the prestressed composite structure design and the theory of equal strength are used to determine the parameters of accumulator barrel, such as the internal cylinder of the composite cylinder, the radii of the inner and outer cylinders, the radius of sub-layer and the optimal interference. Then the ANSYS software is used to analyze the cylinder model with the finite element method, the equivalent stress of the effective node along the wall thickness of the simulation model is obtained by path extraction method and the distribution curves of the equivalent stress along the wall thickness with different internal pressure are also obtained. By analyzing the simulated results and curves, the design parameters of accumulator barrel meet the expected strength requirement.
2015, 34(11): 1686-1692.
doi: 10.13433/j.cnki.1003-8728.2015.1109
Abstract:
Considering the special working condition of high efficiency & precision grinder which is supported by liquid hybrid bearings, we take the impact of the bearing oil film temperature into account for analyzing the static and dynamic characteristic of spindle system. A model for coupling liquid hybrid bearing and oil film is built to calculate bearing oil film temperature and dynamic bearing stiffness which change according to the spindle speed and oil pressure. Then the spindle system's static and dynamic deflections, as well as the natural frequencies that are influenced by the temperature of the bearing oil film, and solved after analysis of its static and dynamic properties. The results show that the thermal characteristic of the bearing oil film has a significant impact on the spindle system's static and dynamic deflections.
Considering the special working condition of high efficiency & precision grinder which is supported by liquid hybrid bearings, we take the impact of the bearing oil film temperature into account for analyzing the static and dynamic characteristic of spindle system. A model for coupling liquid hybrid bearing and oil film is built to calculate bearing oil film temperature and dynamic bearing stiffness which change according to the spindle speed and oil pressure. Then the spindle system's static and dynamic deflections, as well as the natural frequencies that are influenced by the temperature of the bearing oil film, and solved after analysis of its static and dynamic properties. The results show that the thermal characteristic of the bearing oil film has a significant impact on the spindle system's static and dynamic deflections.
2015, 34(11): 1693-1698.
doi: 10.13433/j.cnki.1003-8728.2015.1110
Abstract:
Firstly, the dynamics theoretical basis is reviewed based on the finite element modal analysis technique and the impact dynamic response. Taking the rotating device system of hydraulic excavator as study subject, we research dynamics analysis of hydraulic excavator's rotating device by combining the dynamics theory with the finite element analysis. The dynamics model of rotating device system is established, and the coupled finite element model of rotating device turntable-rotary support frame-rotating mechanism is established, the modal analysis is conducted based on the finite element model,the shock-resistant dynamic performance was assessed for rotating device system, the impact dynamic response was analyzed with the modal acceleration method. A theoretical basis from the study results is provided for the study of structural dynamics and anti-shock performance of hydraulic excavator's rotating device system.
Firstly, the dynamics theoretical basis is reviewed based on the finite element modal analysis technique and the impact dynamic response. Taking the rotating device system of hydraulic excavator as study subject, we research dynamics analysis of hydraulic excavator's rotating device by combining the dynamics theory with the finite element analysis. The dynamics model of rotating device system is established, and the coupled finite element model of rotating device turntable-rotary support frame-rotating mechanism is established, the modal analysis is conducted based on the finite element model,the shock-resistant dynamic performance was assessed for rotating device system, the impact dynamic response was analyzed with the modal acceleration method. A theoretical basis from the study results is provided for the study of structural dynamics and anti-shock performance of hydraulic excavator's rotating device system.
2015, 34(11): 1699-1704.
doi: 10.13433/j.cnki.1003-8728.2015.1111
Abstract:
The time varying reliability analysis method considering fuzzy failure criterion is proposed to deal with the time varying reliability problems of the engineering structures, which can be used to solve the reliability problems with time varying loads and resistances. In this method, the time varying random processes performance function subject to fuzzy failure criteria is firstly discretized, then the basic theory of fuzzy sets is applied and new random variables are introduced to get the equivalent performance function in different time periods. Eventually the time varying reliability problem subject to fuzzy failure criterion is simplified into a static probabilistic reliability problem, which can be solved by a second moment method and the time varying reliability and failure probability can be obtained. Finally, a type of machinery parts and gears are investigated as examples, and the time varying reliability curve and failure probability curve subject to fuzzy failure criterion is obtained. The results show the effectiveness of the present method.
The time varying reliability analysis method considering fuzzy failure criterion is proposed to deal with the time varying reliability problems of the engineering structures, which can be used to solve the reliability problems with time varying loads and resistances. In this method, the time varying random processes performance function subject to fuzzy failure criteria is firstly discretized, then the basic theory of fuzzy sets is applied and new random variables are introduced to get the equivalent performance function in different time periods. Eventually the time varying reliability problem subject to fuzzy failure criterion is simplified into a static probabilistic reliability problem, which can be solved by a second moment method and the time varying reliability and failure probability can be obtained. Finally, a type of machinery parts and gears are investigated as examples, and the time varying reliability curve and failure probability curve subject to fuzzy failure criterion is obtained. The results show the effectiveness of the present method.
2015, 34(11): 1705-1709.
doi: 10.13433/j.cnki.1003-8728.2015.1112
Abstract:
Machine tool guide is the relative movement datum of each moving parts. Guide error changes the relative positions of the moving parts, resulting in a relative movement error. It will cause the table motion error and finally affects the machining accuracy. The effect of the linear rolling guide parallelism error on the table motion error is studied. According to the Hertz contact theory, we analyze the relationship between the ball bearing and the contact deformation. Then, the table motion error is obtained with the homogeneous coordinate transformation method and the minimum complementary energy principle. Comparing the calculation with simulation results, the algorithm can accurately calculate the table motion error.
Machine tool guide is the relative movement datum of each moving parts. Guide error changes the relative positions of the moving parts, resulting in a relative movement error. It will cause the table motion error and finally affects the machining accuracy. The effect of the linear rolling guide parallelism error on the table motion error is studied. According to the Hertz contact theory, we analyze the relationship between the ball bearing and the contact deformation. Then, the table motion error is obtained with the homogeneous coordinate transformation method and the minimum complementary energy principle. Comparing the calculation with simulation results, the algorithm can accurately calculate the table motion error.
2015, 34(11): 1710-1716.
doi: 10.13433/j.cnki.1003-8728.2015.1113
Abstract:
We studied the control structure and strategy of the multi-axis synchronization control system used in light industrial machinery to improve its control accuracy. We analyzed some traditional synchronization control strategies and improved the traditional cross-coupling control structure in order to reduce its synchronous error in position and the controller's huge amount of online calculation caused by too many motors. Then we proposed an adjacent coupling multi-axis synchronization control strategy with fuzzy compensation. The fuzzy PI (Proportional-Integral ) control algorithm was used in the adjacent deviation compensation block, which can maintain good synchronized stability behavior of the multi-axis synchronization control system when it has load disturbance. The computer simulation and experiment results show that this synchronization control strategy has high control accuracy, quick convergence rate, good stability behavior and can quickly satisfy the requirements for synchronization control.
We studied the control structure and strategy of the multi-axis synchronization control system used in light industrial machinery to improve its control accuracy. We analyzed some traditional synchronization control strategies and improved the traditional cross-coupling control structure in order to reduce its synchronous error in position and the controller's huge amount of online calculation caused by too many motors. Then we proposed an adjacent coupling multi-axis synchronization control strategy with fuzzy compensation. The fuzzy PI (Proportional-Integral ) control algorithm was used in the adjacent deviation compensation block, which can maintain good synchronized stability behavior of the multi-axis synchronization control system when it has load disturbance. The computer simulation and experiment results show that this synchronization control strategy has high control accuracy, quick convergence rate, good stability behavior and can quickly satisfy the requirements for synchronization control.
2015, 34(11): 1717-1722.
doi: 10.13433/j.cnki.1003-8728.2015.1114
Abstract:
Numerical analysis was performed to study the flow fields and heat transfer characteristics on a heated plate under the interaction of cyclone flow near rotating disk and jet impinging by simulating the grinding process. The effects of rotating speed and direction on convective heat transfer were analyzed. The results and their analysis show preliminarily that: 1) the penetration capacity of impinging jet into the contact area between rotational disk and heated surface is suppressed under the cyclone flow induced by the rotating disk, but the interaction of cyclone flow and jet impingement is beneficial for the enhancement of convective heat transfer compared to static disk case; 2) when the jet impinging direction is consistent with the rotating direction of rotating disk, the interaction of cyclone flow and jet impinging is beneficial for the enhancement of convective heat transfer near grinding region, especially at higher rotating speed.
Numerical analysis was performed to study the flow fields and heat transfer characteristics on a heated plate under the interaction of cyclone flow near rotating disk and jet impinging by simulating the grinding process. The effects of rotating speed and direction on convective heat transfer were analyzed. The results and their analysis show preliminarily that: 1) the penetration capacity of impinging jet into the contact area between rotational disk and heated surface is suppressed under the cyclone flow induced by the rotating disk, but the interaction of cyclone flow and jet impingement is beneficial for the enhancement of convective heat transfer compared to static disk case; 2) when the jet impinging direction is consistent with the rotating direction of rotating disk, the interaction of cyclone flow and jet impinging is beneficial for the enhancement of convective heat transfer near grinding region, especially at higher rotating speed.
2015, 34(11): 1723-1727.
doi: 10.13433/j.cnki.1003-8728.2015.1115
Abstract:
According to the coaxial visual original image sensing characteristics of the molten pool and holes which were collected in the coaxial monitoring system, we analyzed the digital image processing methods and put forward corresponding image processing process. By monitoring the grayscale distribution of molten pool along the vertical direction of velocity, the monitoring of the welding pool width is achieved. By monitoring the top and bottom size of hole, the penetration status was monitored. After dealing with the image of the welding area, the coaxial monitoring molten pool images can be clearly acquired including contour and pore size, which made the preparation for monitoring the penetration status. For laser butt welding, the processing algorithm of seam tracking was put forward, which not only realized the monitoring of welding quality including fusion width and penetration status, but also achieved the integration of welding quality and welding seam tracking monitoring.
According to the coaxial visual original image sensing characteristics of the molten pool and holes which were collected in the coaxial monitoring system, we analyzed the digital image processing methods and put forward corresponding image processing process. By monitoring the grayscale distribution of molten pool along the vertical direction of velocity, the monitoring of the welding pool width is achieved. By monitoring the top and bottom size of hole, the penetration status was monitored. After dealing with the image of the welding area, the coaxial monitoring molten pool images can be clearly acquired including contour and pore size, which made the preparation for monitoring the penetration status. For laser butt welding, the processing algorithm of seam tracking was put forward, which not only realized the monitoring of welding quality including fusion width and penetration status, but also achieved the integration of welding quality and welding seam tracking monitoring.
2015, 34(11): 1728-1732.
doi: 10.13433/j.cnki.1003-8728.2015.1116
Abstract:
A global path planning method, based on the firefly algorithm with variable parameters and Maklink graph, is proposed to solve the global path planning problem in two-dimensional static environment. At first, the continuous firefly algorithm with fixed parameters is modified to be the discrete firefly algorithm with variable parameters. Then, according to the characteristics of the global path planning problem we define, the encoding rules and the distance between fireflies. Finally, taking the environment with some obstacles of stochastic shape as the example, and based on the Maklink graph, the firefly algorithm with variable parameters is adopted to optimize the path. The results show that the proposed method can not only solve the discrete path planning problem well, but also has better performance than the standard firefly algorithm. Furthermore, it's better than the PSO algorithm in convergence speed and computation stability.
A global path planning method, based on the firefly algorithm with variable parameters and Maklink graph, is proposed to solve the global path planning problem in two-dimensional static environment. At first, the continuous firefly algorithm with fixed parameters is modified to be the discrete firefly algorithm with variable parameters. Then, according to the characteristics of the global path planning problem we define, the encoding rules and the distance between fireflies. Finally, taking the environment with some obstacles of stochastic shape as the example, and based on the Maklink graph, the firefly algorithm with variable parameters is adopted to optimize the path. The results show that the proposed method can not only solve the discrete path planning problem well, but also has better performance than the standard firefly algorithm. Furthermore, it's better than the PSO algorithm in convergence speed and computation stability.
2015, 34(11): 1733-1737.
doi: 10.13433/j.cnki.1003-8728.2015.1117
Abstract:
In order to control the heating of the oil film of a CNC vertical lathe hydrostatic rotary table, we use the CFD (computational fluid dynamics) software Fluent to simulate the temperature field of the oil film and then discuss the temperature distribution regularity at its different rotational speed and viscosity. The simulation results and their analysis show that the high-temperature zone mainly concentrates on the outside edge of radial seal oil. Assuming the power consumption is minimal, we obtain the viscosity of the oil film with MATLAB to optimize its viscosity factor. When the viscosity was 0.061 7 Pa·s, the vertical lathe hydrostatic rotary table has the minimum total power consumption, and its oil film temperature is also low.
In order to control the heating of the oil film of a CNC vertical lathe hydrostatic rotary table, we use the CFD (computational fluid dynamics) software Fluent to simulate the temperature field of the oil film and then discuss the temperature distribution regularity at its different rotational speed and viscosity. The simulation results and their analysis show that the high-temperature zone mainly concentrates on the outside edge of radial seal oil. Assuming the power consumption is minimal, we obtain the viscosity of the oil film with MATLAB to optimize its viscosity factor. When the viscosity was 0.061 7 Pa·s, the vertical lathe hydrostatic rotary table has the minimum total power consumption, and its oil film temperature is also low.
2015, 34(11): 1738-1743.
doi: 10.13433/j.cnki.1003-8728.2015.1118
Abstract:
In front impact of coach, lower extremities of driver are often injured because of the large intrusion deformation of front wall. To reduce the injury risk of driver's lower extremities, a type of driver knee airbag was designed and optimized with computer simulations. A finite element model of a 12 meter long coach was developed with Ls-dyna software. The simulation of the front impact of the coach model was carried out and the feasibility of the coach model was analyzed. Furthermore, the acceleration of the coach was acquired at the bottom of driver seat, then the front impact model for driver restraint system was established via MADYMO dynamic code. This model includes coach driver compartment, driver seat, three-point safety belt, steering system and knee airbag. The simulated acceleration curve of coach front impact was used as the input load condition in MADYMO model of the coach driver restraint system. The influence of eight design parameters of belt and knee airbag on the injuries of driver's lower extremities was analyzed. The results show that there are three key influence factors, including initiation moment of knee airbag, the strap length of knee airbag and the area coefficient for the exhaust openings of knee airbag. Based on multi-objective genetic algorithms, the optimization for the knee airbag was conducted according to these three factors. The injury risk of driver's lower extremities is greatly reduced after optimization.
In front impact of coach, lower extremities of driver are often injured because of the large intrusion deformation of front wall. To reduce the injury risk of driver's lower extremities, a type of driver knee airbag was designed and optimized with computer simulations. A finite element model of a 12 meter long coach was developed with Ls-dyna software. The simulation of the front impact of the coach model was carried out and the feasibility of the coach model was analyzed. Furthermore, the acceleration of the coach was acquired at the bottom of driver seat, then the front impact model for driver restraint system was established via MADYMO dynamic code. This model includes coach driver compartment, driver seat, three-point safety belt, steering system and knee airbag. The simulated acceleration curve of coach front impact was used as the input load condition in MADYMO model of the coach driver restraint system. The influence of eight design parameters of belt and knee airbag on the injuries of driver's lower extremities was analyzed. The results show that there are three key influence factors, including initiation moment of knee airbag, the strap length of knee airbag and the area coefficient for the exhaust openings of knee airbag. Based on multi-objective genetic algorithms, the optimization for the knee airbag was conducted according to these three factors. The injury risk of driver's lower extremities is greatly reduced after optimization.
2015, 34(11): 1744-1749.
doi: 10.13433/j.cnki.1003-8728.2015.1119
Abstract:
The vertical vibration of the in-wheel motor electric vehicle (IWM-EV) induced by larger unsprung mass is analyzed based on the power flow method. The computer simulation results show that due to the unsprung mass increase of IWM-EV, energy dissipation of the suspension and wheel is increasing, which will cause adverse effects on not just the ride comfort but the maneuver stability. To decrease the effect, a new shock absorber at the vehicle body is designed. Compared to another absorber at the wheel, it can avoid resonance in the human sensitive frequency range. An optimization design is carried out on the parameters of the absorber. The simulation results show that as an effective way to improve the dynamics, the new shock absorber can reduce the vibration energy dissipation of IWM-EV.
The vertical vibration of the in-wheel motor electric vehicle (IWM-EV) induced by larger unsprung mass is analyzed based on the power flow method. The computer simulation results show that due to the unsprung mass increase of IWM-EV, energy dissipation of the suspension and wheel is increasing, which will cause adverse effects on not just the ride comfort but the maneuver stability. To decrease the effect, a new shock absorber at the vehicle body is designed. Compared to another absorber at the wheel, it can avoid resonance in the human sensitive frequency range. An optimization design is carried out on the parameters of the absorber. The simulation results show that as an effective way to improve the dynamics, the new shock absorber can reduce the vibration energy dissipation of IWM-EV.
2015, 34(11): 1750-1755.
doi: 10.13433/j.cnki.1003-8728.2015.1120
Abstract:
Fender is one of the auto-body panel which is the greatest difficult to form. The forming process of fender is determined by its structural characteristics, and the number of forming process directly affect its cost of production and its forming precision. Studying the structure characteristics of various fender and their stamping process, we propose the structure optimization design method of fender product based on the orthogonal design. With a car fender development as an example, the fender is optimized and the key technology for the four-operation stamping scheme of fender is researched. This optimization analysis method can guide fender product structure design to meet the four-operation forming scheme for the car body structure design.
Fender is one of the auto-body panel which is the greatest difficult to form. The forming process of fender is determined by its structural characteristics, and the number of forming process directly affect its cost of production and its forming precision. Studying the structure characteristics of various fender and their stamping process, we propose the structure optimization design method of fender product based on the orthogonal design. With a car fender development as an example, the fender is optimized and the key technology for the four-operation stamping scheme of fender is researched. This optimization analysis method can guide fender product structure design to meet the four-operation forming scheme for the car body structure design.
2015, 34(11): 1756-1760.
doi: 10.13433/j.cnki.1003-8728.2015.1121
Abstract:
The selection of parameters for a hybrid electric vehicle (HEV) control strategy has a significant influence on its performance. An optimization model for the HEV control strategy is set up to optimize the parameters of the HEV control strategy, including a constraint indicator of power performance and an evaluation indicator of fuel consumption and emissions. Since the parameter optimization for the HEV control strategy is a multi-objective optimization problem, evaluation indicators are integrated into one objective function by weighting their coefficients. GATBX (Genetic Algorithms Tool Box) was used to optimize the parameters for the HEV control strategy, and the performance of the optimized HEV was simulated by ADVISOR. The simulation results and their analysis show that the optimized control strategy can effectively reduce fuel consumption and emissions without sacrificing power performance and fuel consumption and that NOx emission is reduced by 17% and that HC and CO emissions are reduced by about 7%.
The selection of parameters for a hybrid electric vehicle (HEV) control strategy has a significant influence on its performance. An optimization model for the HEV control strategy is set up to optimize the parameters of the HEV control strategy, including a constraint indicator of power performance and an evaluation indicator of fuel consumption and emissions. Since the parameter optimization for the HEV control strategy is a multi-objective optimization problem, evaluation indicators are integrated into one objective function by weighting their coefficients. GATBX (Genetic Algorithms Tool Box) was used to optimize the parameters for the HEV control strategy, and the performance of the optimized HEV was simulated by ADVISOR. The simulation results and their analysis show that the optimized control strategy can effectively reduce fuel consumption and emissions without sacrificing power performance and fuel consumption and that NOx emission is reduced by 17% and that HC and CO emissions are reduced by about 7%.
2015, 34(11): 1761-1768.
doi: 10.13433/j.cnki.1003-8728.2015.1122
Abstract:
In order to improve the potential energy recovery efficiency of electric forklift,mathematical models of components of the energy recovery system and the mathematical model of potential energy recovery efficiency were given, the influence factors of the potential energy recovery efficiency in electric forklift were studied. AMESim and Virtual.lab Motion software were used to analyze potential energy recovery system. Then through experiments, the effectiveness of computer simulation model and the accuracy of simulation results are tested. Research results show that the efficiency of potential energy recovery increases with the increase of the load and the displacement of hydraulic motor,and increases with the decrease of the falling speed,the falling acceleration, the rotational inertia of hydraulic motor, the piston area of hoist cylinder and the mass of hoist cylinder moving parts.
In order to improve the potential energy recovery efficiency of electric forklift,mathematical models of components of the energy recovery system and the mathematical model of potential energy recovery efficiency were given, the influence factors of the potential energy recovery efficiency in electric forklift were studied. AMESim and Virtual.lab Motion software were used to analyze potential energy recovery system. Then through experiments, the effectiveness of computer simulation model and the accuracy of simulation results are tested. Research results show that the efficiency of potential energy recovery increases with the increase of the load and the displacement of hydraulic motor,and increases with the decrease of the falling speed,the falling acceleration, the rotational inertia of hydraulic motor, the piston area of hoist cylinder and the mass of hoist cylinder moving parts.
2015, 34(11): 1769-1773.
doi: 10.13433/j.cnki.1003-8728.2015.1123
Abstract:
The paper investigated the tire contact pressure characteristics in the steady state rolling condition based on tire ring model. Unsymmetrical factor is first introduced for measuring the asymmetry of contact pressure in tire rolling. The influence of tire structural parameters on unsymmetrical factor of tire contact pressure is explored. The results show that angular velocity, damping coefficient, belt effective density, inflation pressure, vertical load, sidewall radial spring rate,belt radial spring rate and belt bending stiffness are the most important factors on unsymmetrical factor of tire contact pressure, in that order. In parameter variations of ±40%, great nonlinear features are shown on the influence of vertical load, inflation pressure and sidewall radial spring rate on tire rolling unsymmetrical factor, in the order.
The paper investigated the tire contact pressure characteristics in the steady state rolling condition based on tire ring model. Unsymmetrical factor is first introduced for measuring the asymmetry of contact pressure in tire rolling. The influence of tire structural parameters on unsymmetrical factor of tire contact pressure is explored. The results show that angular velocity, damping coefficient, belt effective density, inflation pressure, vertical load, sidewall radial spring rate,belt radial spring rate and belt bending stiffness are the most important factors on unsymmetrical factor of tire contact pressure, in that order. In parameter variations of ±40%, great nonlinear features are shown on the influence of vertical load, inflation pressure and sidewall radial spring rate on tire rolling unsymmetrical factor, in the order.
2015, 34(11): 1774-1778.
doi: 10.13433/j.cnki.1003-8728.2015.1124
Abstract:
The study was difficultly taken for the Q6 crash test dummy existing some problems, such as structural complexity and unclear of material parameters. The geometry unaffected by metal was constructed using CT-scans. The metal-bearing part was designed using a centroid measuring tool applying trial and error based on the centroid consistent. Furthermore, the new drainage law was established and the density of hip skin and clavicle was reserved by the way. The density of composite component was reserved in the base of the designed matrix algebra method. Ultimately, the main geometry and density of the Q6 child dummy was established based on those methods. It offers the foundation of improvement and development of the finite element model of child crash dummy.
The study was difficultly taken for the Q6 crash test dummy existing some problems, such as structural complexity and unclear of material parameters. The geometry unaffected by metal was constructed using CT-scans. The metal-bearing part was designed using a centroid measuring tool applying trial and error based on the centroid consistent. Furthermore, the new drainage law was established and the density of hip skin and clavicle was reserved by the way. The density of composite component was reserved in the base of the designed matrix algebra method. Ultimately, the main geometry and density of the Q6 child dummy was established based on those methods. It offers the foundation of improvement and development of the finite element model of child crash dummy.
2015, 34(11): 1779-1783.
doi: 10.13433/j.cnki.1003-8728.2015.1125
Abstract:
The effect of laser shock processing (LSP) on the fatigue corrosion of AZ31 magnesium alloy has been analyzed. AZ31 magnesium alloy was processed with Nd:YAG laser with the wavelength of 1064nm and pulse width of 10ns. Microstructures were observed with transmission electron microscopy. The fatigue life of AZ31 magnesium alloy after LSP increased about 38.25% in air and 183.47% in solution respectively. Transmission electron microscopy observation showed that plastic deformation with ultrahigh strain rate occurred because of laser shock wave at the surface layer of AZ31 magnesium alloy. Meanwhile, extensive dislocations and twins were generated. High density dislocations tangled and intersected with twins, which led to the refinement of grains. Fitting curves show that the fatigue crack propagation rate of LSP samples is less than that of un-LSP samples in air and in 3.5% NaCl solution. The residual compressive stress, grain refinement and higher corrosion resistance with LSP are main factors to hinder the fatigue crack propagation of AZ31 magnesium alloy.
The effect of laser shock processing (LSP) on the fatigue corrosion of AZ31 magnesium alloy has been analyzed. AZ31 magnesium alloy was processed with Nd:YAG laser with the wavelength of 1064nm and pulse width of 10ns. Microstructures were observed with transmission electron microscopy. The fatigue life of AZ31 magnesium alloy after LSP increased about 38.25% in air and 183.47% in solution respectively. Transmission electron microscopy observation showed that plastic deformation with ultrahigh strain rate occurred because of laser shock wave at the surface layer of AZ31 magnesium alloy. Meanwhile, extensive dislocations and twins were generated. High density dislocations tangled and intersected with twins, which led to the refinement of grains. Fitting curves show that the fatigue crack propagation rate of LSP samples is less than that of un-LSP samples in air and in 3.5% NaCl solution. The residual compressive stress, grain refinement and higher corrosion resistance with LSP are main factors to hinder the fatigue crack propagation of AZ31 magnesium alloy.
2015, 34(11): 1784-1788.
doi: 10.13433/j.cnki.1003-8728.2015.1126
Abstract:
Based on the CATIA Parameterization, a design method for the structure of porous material is putforward. The present method to establish porous structure data-base was introduced, including the parametric modeling, building and employing of the porous structure data-base. At last,the process of the rapid design for aeronautic, astronautic and biomedical porous materials with porous structure data-base was presented and the porous metal materials with different unit style were fabricated with the selective electron beam melting.
Based on the CATIA Parameterization, a design method for the structure of porous material is putforward. The present method to establish porous structure data-base was introduced, including the parametric modeling, building and employing of the porous structure data-base. At last,the process of the rapid design for aeronautic, astronautic and biomedical porous materials with porous structure data-base was presented and the porous metal materials with different unit style were fabricated with the selective electron beam melting.
2015, 34(11): 1789-1793.
doi: 10.13433/j.cnki.1003-8728.2015.1127
Abstract:
For the sparse failure data of high reliability products used in the aircraft design,it is difficult to determining the distribution model of data,which can reflect the statistic characteristics of components' failure information. A novel method is proposed to describe the uncertainty of failure data based on Kriging model in order to mine the reliability information of component. Then, a large number of samples based on the Kriging model can be drawn, and the larger sample completely reflects the properties of the original small sample, which is convenient for system reliability analysis based on Monte Carlo sampling. Meanwhile, a new measure index about Cumulative Distribution Function (CDF) is established to measure the statistical characteristic difference between the uncertainty model based on Kriging method and the original failure data. Take the hydraulic pump as an example, the result of measuring analysis illustrates the proposed method is more exact to describe the statistical characteristic of the original failure data than traditional methods.
For the sparse failure data of high reliability products used in the aircraft design,it is difficult to determining the distribution model of data,which can reflect the statistic characteristics of components' failure information. A novel method is proposed to describe the uncertainty of failure data based on Kriging model in order to mine the reliability information of component. Then, a large number of samples based on the Kriging model can be drawn, and the larger sample completely reflects the properties of the original small sample, which is convenient for system reliability analysis based on Monte Carlo sampling. Meanwhile, a new measure index about Cumulative Distribution Function (CDF) is established to measure the statistical characteristic difference between the uncertainty model based on Kriging method and the original failure data. Take the hydraulic pump as an example, the result of measuring analysis illustrates the proposed method is more exact to describe the statistical characteristic of the original failure data than traditional methods.
2015, 34(11): 1794-1799.
doi: 10.13433/j.cnki.1003-8728.2015.1128
Abstract:
In order to improve the accuracy of space docking platform, it's necessary to analyze the errors and research the error calibration. Based on forward kinematics solution and inverse solution model, the kinematics error calibration model of 6-DOF parallel mechanism is established with total differential method. For the sake of identifying the value of each error more effective, a new error calibration method based on the genetic algorithm to search the optimal measuring points for calibration is proposed to reduce the effect of measurement noise during the calibration, in which the matrix condition number as the optimization objective. The results show that the calibration is effective even with less measurement points; it has the better anti-noise capability. At last, the effectiveness of proposed method is validated with numerical simulation method.
In order to improve the accuracy of space docking platform, it's necessary to analyze the errors and research the error calibration. Based on forward kinematics solution and inverse solution model, the kinematics error calibration model of 6-DOF parallel mechanism is established with total differential method. For the sake of identifying the value of each error more effective, a new error calibration method based on the genetic algorithm to search the optimal measuring points for calibration is proposed to reduce the effect of measurement noise during the calibration, in which the matrix condition number as the optimization objective. The results show that the calibration is effective even with less measurement points; it has the better anti-noise capability. At last, the effectiveness of proposed method is validated with numerical simulation method.
2015, 34(11): 1800-1804.
doi: 10.13433/j.cnki.1003-8728.2015.1129
Abstract:
The technique about wing flight load measurement based on coordinated multi-point loading test was researched. In an aircraft wing load calibration test, the automatic hydraulic loading system was used for the first time, and a new aircraft restraint device had been developed, thus realizing the multi-point coordinated load calibration test, in which the test data were collected by the airborne testing system. An establishment method of the wing load model was proposed, which reasonable and reliable were validated through both ground test and flight test. The results show that this method can establish more highly accurate wing load model.
The technique about wing flight load measurement based on coordinated multi-point loading test was researched. In an aircraft wing load calibration test, the automatic hydraulic loading system was used for the first time, and a new aircraft restraint device had been developed, thus realizing the multi-point coordinated load calibration test, in which the test data were collected by the airborne testing system. An establishment method of the wing load model was proposed, which reasonable and reliable were validated through both ground test and flight test. The results show that this method can establish more highly accurate wing load model.
