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RSS2016 Vol. 35, No. 6
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2016, 35(6): 821-825.
doi: 10.13433/j.cnki.1003-8728.2016.0601
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Abstract:
In this paper, the fatigue damage of missile hanging under stochastic excitation is calculated with the finite element method, and the effect factors of the fatigue are also analyzed. First, the irregular factors and the root mean square (RMS) stress are calculated with the power spectral density method. Then the effects of the material parameters and modal damping of the structure are evaluated by random vibration analysis. At last, the mean stress correction coefficient is deduced with the Goodman method. The results show that the standard deviation of the stress responses is the principal factor that affects the fatigue life of missile hanging; material parameters and modal damping of the structure also influence the fatigue life to some extent; in addition, the effect of the mean stress cannot be ignored.
In this paper, the fatigue damage of missile hanging under stochastic excitation is calculated with the finite element method, and the effect factors of the fatigue are also analyzed. First, the irregular factors and the root mean square (RMS) stress are calculated with the power spectral density method. Then the effects of the material parameters and modal damping of the structure are evaluated by random vibration analysis. At last, the mean stress correction coefficient is deduced with the Goodman method. The results show that the standard deviation of the stress responses is the principal factor that affects the fatigue life of missile hanging; material parameters and modal damping of the structure also influence the fatigue life to some extent; in addition, the effect of the mean stress cannot be ignored.
2016, 35(6): 826-832.
doi: 10.13433/j.cnki.1003-8728.2016.0602
Abstract:
Aiming to the two points nearby the center of screw pump rotor, the equations of motion is built to study the contact pressure of stator and rotor of screw pump, and the biggest difference between the results via finite element method and Hertz method is 2.46% and the smallest is 0.048% at the interferences from 0.05 to 0.3 mm. In the contact nonlinear analysis of the stator and rotor of screw pump, the contact surface boundary conditions by the penalty function method is used in equations, and then get the contact pressure with ANSYS Workbench software. It shows that the influence of contact place and interference on the contact pressure is great, while the influence of the rotor speed and friction coefficient on the contact pressure is slight when the friction coefficient is not equal 0 and the speed is higher.
Aiming to the two points nearby the center of screw pump rotor, the equations of motion is built to study the contact pressure of stator and rotor of screw pump, and the biggest difference between the results via finite element method and Hertz method is 2.46% and the smallest is 0.048% at the interferences from 0.05 to 0.3 mm. In the contact nonlinear analysis of the stator and rotor of screw pump, the contact surface boundary conditions by the penalty function method is used in equations, and then get the contact pressure with ANSYS Workbench software. It shows that the influence of contact place and interference on the contact pressure is great, while the influence of the rotor speed and friction coefficient on the contact pressure is slight when the friction coefficient is not equal 0 and the speed is higher.
2016, 35(6): 833-839.
doi: 10.13433/j.cnki.1003-8728.2016.0603
Abstract:
Because deformation and clamping stagnation occur in the extension and retraction mechanism of a certain kind of rescue robot, this paper explores the extension and retraction mechanism's loading characteristics and causes of its failure. Its rigid-flexible coupling model was established by using computer simulation analysis software. How machining errors and assembly clearance affect the deformation of the mechanical components of the rescue robot was discussed. The error analysis shows that the additional moment caused by the mechanical structural design and machining errors as well as assembly clearances are significant contributors to the deformation of the extension and retraction mechanism. This paper also improved the design and redoes the computer simulation analysis. Compared with the previous results, the current results show that the improved design makes the loading characteristics reasonable and reduces effectively deformation and clamping stagnation.
Because deformation and clamping stagnation occur in the extension and retraction mechanism of a certain kind of rescue robot, this paper explores the extension and retraction mechanism's loading characteristics and causes of its failure. Its rigid-flexible coupling model was established by using computer simulation analysis software. How machining errors and assembly clearance affect the deformation of the mechanical components of the rescue robot was discussed. The error analysis shows that the additional moment caused by the mechanical structural design and machining errors as well as assembly clearances are significant contributors to the deformation of the extension and retraction mechanism. This paper also improved the design and redoes the computer simulation analysis. Compared with the previous results, the current results show that the improved design makes the loading characteristics reasonable and reduces effectively deformation and clamping stagnation.
2016, 35(6): 840-845.
doi: 10.13433/j.cnki.1003-8728.2016.0604
Abstract:
Mechanical assembly is an important process in manufacturing electromechanical products and directly affects the dynamic quality of a whole product. Conventional quality inspection and analysis of mechanical assembly are currently concentrated on "static quality", such as size-coordinations and tolerances of shaping and positioning and so on, which results in incomplete estimation on the assembly quality. After explaining the concept of "dynamic quality of mechanical assembly", functional relations between the dynamic transferring characteristics involved in mechanical assembly have been explicitly defined, and the affects of assembling process on the characteristics of both the substructural components and the assembly system are analyzed and discussed on the basis of substructuring and eigenvalue analysis. Consequently, the measured frequency response functions (FRFs) are used to compute the mean intrinsic values of assembly ratio-matrix that is employed as a quantitative metrics for dynamic quality inspection and estimation of mechanical assembly. By a lumped-parameter model and an applied experimental model of "two-level substructures" of an assembly, the analytical results and the developed quantitative computational approach are well validated. The present study can improve the conventional methodology in quality inspection and estimation of mechanical assembly.
Mechanical assembly is an important process in manufacturing electromechanical products and directly affects the dynamic quality of a whole product. Conventional quality inspection and analysis of mechanical assembly are currently concentrated on "static quality", such as size-coordinations and tolerances of shaping and positioning and so on, which results in incomplete estimation on the assembly quality. After explaining the concept of "dynamic quality of mechanical assembly", functional relations between the dynamic transferring characteristics involved in mechanical assembly have been explicitly defined, and the affects of assembling process on the characteristics of both the substructural components and the assembly system are analyzed and discussed on the basis of substructuring and eigenvalue analysis. Consequently, the measured frequency response functions (FRFs) are used to compute the mean intrinsic values of assembly ratio-matrix that is employed as a quantitative metrics for dynamic quality inspection and estimation of mechanical assembly. By a lumped-parameter model and an applied experimental model of "two-level substructures" of an assembly, the analytical results and the developed quantitative computational approach are well validated. The present study can improve the conventional methodology in quality inspection and estimation of mechanical assembly.
2016, 35(6): 846-852.
doi: 10.13433/j.cnki.1003-8728.2016.0605
Abstract:
In order to study the motorized spindle's modal under the high speed running condition and the influence of different rotation speed on the motorized spindle's natural frequency, the finite element method is used for the modeling and analysis of the motorized spindle. Then the modal analysis of the motorized spindle is made on ambient excitation. Though the data comparison, it can be found that with the rise of rotating speed, the combination effect of the centrifugal force and the bearing softening reduces the radial support stiffness of the bearing, resulting in the downward trend of the first three natural frequencies. The impact on the high natural frequency is related to the speed. We can get to know the ambient excitation with the vibration caused by the spindle's speed as the exciting force can be able to eliminate the complex interference from the environment and the virtual modal for identifying the modal parameters of the spindle system.
In order to study the motorized spindle's modal under the high speed running condition and the influence of different rotation speed on the motorized spindle's natural frequency, the finite element method is used for the modeling and analysis of the motorized spindle. Then the modal analysis of the motorized spindle is made on ambient excitation. Though the data comparison, it can be found that with the rise of rotating speed, the combination effect of the centrifugal force and the bearing softening reduces the radial support stiffness of the bearing, resulting in the downward trend of the first three natural frequencies. The impact on the high natural frequency is related to the speed. We can get to know the ambient excitation with the vibration caused by the spindle's speed as the exciting force can be able to eliminate the complex interference from the environment and the virtual modal for identifying the modal parameters of the spindle system.
2016, 35(6): 853-857.
doi: 10.13433/j.cnki.1003-8728.2016.0606
Abstract:
The result of online ultrasonic detection of wear debris has close relations with acoustic field features of ultrasonic transducer. Online sensor of wear debris in oil is designed by acoustic field features of ultrasonic transducer. Numerical simulation method can effectively analyze the characteristics of ultrasonic sound field. First, online ultrasonic detection method of wear debris is theoretically reviewed. Then, the finite-difference time-domain method (FDTD) is utilized to solve KZK equation for simulating sound field of ultrasonic transducer. Finally, an experimental system is set up for distribution measurement of ultrasonic sound field in lubrication, and ultrasonic acoustic field feature is measured. The results of simulation and experiment show that FDTD's utilization to solve KZK equation can effectively imitate acoustic field distribution of focused ultrasound transducer in oil. Focal spot of focused ultrasound transducer has an oval shape, and major axis is 4mm and minor axis is 0.4mm. Simulation and experiment show the good consistency. The research builds the foundation for next ultrasonic sensor design of wear debris.
The result of online ultrasonic detection of wear debris has close relations with acoustic field features of ultrasonic transducer. Online sensor of wear debris in oil is designed by acoustic field features of ultrasonic transducer. Numerical simulation method can effectively analyze the characteristics of ultrasonic sound field. First, online ultrasonic detection method of wear debris is theoretically reviewed. Then, the finite-difference time-domain method (FDTD) is utilized to solve KZK equation for simulating sound field of ultrasonic transducer. Finally, an experimental system is set up for distribution measurement of ultrasonic sound field in lubrication, and ultrasonic acoustic field feature is measured. The results of simulation and experiment show that FDTD's utilization to solve KZK equation can effectively imitate acoustic field distribution of focused ultrasound transducer in oil. Focal spot of focused ultrasound transducer has an oval shape, and major axis is 4mm and minor axis is 0.4mm. Simulation and experiment show the good consistency. The research builds the foundation for next ultrasonic sensor design of wear debris.
2016, 35(6): 858-862.
doi: 10.13433/j.cnki.1003-8728.2016.0607
Abstract:
The International Thermonuclear Experimental Reactor-ITER,is a large and complex system, it is a cooperation project of many countries, the cold mass support in the ITER's feeder system is the guarantee for the steady operation of this large system. In this paper, the strength requirements of the support structure, actual temperature, the vacuum conditions etc. have been discussed to elaborate the design process of cold mass support,and the mechanical behaviors of its main parts are obtained by statics analysis using finite element analysis software ANSYS.
The International Thermonuclear Experimental Reactor-ITER,is a large and complex system, it is a cooperation project of many countries, the cold mass support in the ITER's feeder system is the guarantee for the steady operation of this large system. In this paper, the strength requirements of the support structure, actual temperature, the vacuum conditions etc. have been discussed to elaborate the design process of cold mass support,and the mechanical behaviors of its main parts are obtained by statics analysis using finite element analysis software ANSYS.
2016, 35(6): 863-869.
doi: 10.13433/j.cnki.1003-8728.2016.0608
Abstract:
In order to study the control of mobile rescue robot under uncertain system parameters, the kinematics and dynamics model for mobile rescue robots is firstly presented in terms of Jacobian matrices and Ouler-Lagrange. Secondly, the Inverse Dynamics Control is brought forward in joint space, and the effects of the Inverse Dynamics Control due to imperfect compensation of the kinematics and dynamics models are analyzed. Then, the new Robust-Inverse Dynamics Control is designed which is aimed at counteracting the effects of system errors, the stability of the control is proved with Lyapunov functions. At last, the validity, efficiency and robustness of the control algorithms are demonstrated with computer simulation.
In order to study the control of mobile rescue robot under uncertain system parameters, the kinematics and dynamics model for mobile rescue robots is firstly presented in terms of Jacobian matrices and Ouler-Lagrange. Secondly, the Inverse Dynamics Control is brought forward in joint space, and the effects of the Inverse Dynamics Control due to imperfect compensation of the kinematics and dynamics models are analyzed. Then, the new Robust-Inverse Dynamics Control is designed which is aimed at counteracting the effects of system errors, the stability of the control is proved with Lyapunov functions. At last, the validity, efficiency and robustness of the control algorithms are demonstrated with computer simulation.
2016, 35(6): 870-876.
doi: 10.13433/j.cnki.1003-8728.2016.0609
Abstract:
We established the mechanical model of the home-made tri-layer bending polypyrrole conducting polymer actuator based on the equivalent cantilever theory. Through measuring the substrate bending deformation when the low voltage (0~1 V) is applied to the actuator and studying the relationships among voltage, bending displacement and power, we established the functional relationship between voltage and uniformly distributed load. The experimental results show that the voltage and the vertical displacement have a linear relationship. When the voltage is 0.7 V, the vertical displacement can reach 17 mm, and the voltage with strain scaling factor approximation α=0.013 is derived. Furthermore, we calculated the actuator's displacement deviation between theoretical deflection value and measured value. Then we find that the maximum deviation is very small, thus verifying the validity of our model.
We established the mechanical model of the home-made tri-layer bending polypyrrole conducting polymer actuator based on the equivalent cantilever theory. Through measuring the substrate bending deformation when the low voltage (0~1 V) is applied to the actuator and studying the relationships among voltage, bending displacement and power, we established the functional relationship between voltage and uniformly distributed load. The experimental results show that the voltage and the vertical displacement have a linear relationship. When the voltage is 0.7 V, the vertical displacement can reach 17 mm, and the voltage with strain scaling factor approximation α=0.013 is derived. Furthermore, we calculated the actuator's displacement deviation between theoretical deflection value and measured value. Then we find that the maximum deviation is very small, thus verifying the validity of our model.
2016, 35(6): 877-880.
doi: 10.13433/j.cnki.1003-8728.2016.0610
Abstract:
Friction fatigue test of typical slide guide samples was conducted in a reciprocating friction tester to analyze the fatigue damage characteristic of contact surfaces and obtain the friction fatigue exponents. The experiment results indicate that for the samples of HT200 versus 1045 steel, the wear resistance can be increased by 3~4 times and 5~6 times through hardening treatment and boundary lubrication respectively. The calculation results of friction fatigue exponents of HT200 and quenched HT200 under dry friction and boundary lubrication were 1.12, 1.33, 1.43 and 1.41 respectively. The research results can provide the key parameter estimation for the theoretical calculation of fatigue wear of slide guide and it can also conduct the quantitatively analysis of tribology for slide guide.
Friction fatigue test of typical slide guide samples was conducted in a reciprocating friction tester to analyze the fatigue damage characteristic of contact surfaces and obtain the friction fatigue exponents. The experiment results indicate that for the samples of HT200 versus 1045 steel, the wear resistance can be increased by 3~4 times and 5~6 times through hardening treatment and boundary lubrication respectively. The calculation results of friction fatigue exponents of HT200 and quenched HT200 under dry friction and boundary lubrication were 1.12, 1.33, 1.43 and 1.41 respectively. The research results can provide the key parameter estimation for the theoretical calculation of fatigue wear of slide guide and it can also conduct the quantitatively analysis of tribology for slide guide.
2016, 35(6): 881-889.
doi: 10.13433/j.cnki.1003-8728.2016.0611
Abstract:
This paper systematically reviewed the research state of laser soldering in electronic industry, the processing parameters optimization, and its effect on the microstructures and properties of solders/solder joints. In addition, the application of finite element method to laser soldering was analyzed, and the effect mechanism of laser soldering on the solder joints reliability was synchronously discussed. The present review can provide the theory support for the application and further research of laser soldering.
This paper systematically reviewed the research state of laser soldering in electronic industry, the processing parameters optimization, and its effect on the microstructures and properties of solders/solder joints. In addition, the application of finite element method to laser soldering was analyzed, and the effect mechanism of laser soldering on the solder joints reliability was synchronously discussed. The present review can provide the theory support for the application and further research of laser soldering.
Influence of Roundness Error of Spindle on Performance of Hybrid Liquid Bearing in Precision Grinder
2016, 35(6): 890-895.
doi: 10.13433/j.cnki.1003-8728.2016.0612
Abstract:
Considering the roundness error and cylindrical error of spindle in precision grinder, we analyze the performances of hybrid bearing with deep-shallow oil chamber with FLUENT software. The influence of the different types of roundness error and the cylindrical error of spindle on the performance of the hybrid bearing varies with the change in bearing clearance. The results show that load capacity, power consumption and the highest temperature rise of the oil film in the bearing will increase with the increasing of error amplitude, but the variation rule in the bearing oil flow is opposite. The influences of the roundness errors of spindle on the performances of hybrid bearing in the spindle of precision grinder cannot be ignored in order to improve grinding precision.
Considering the roundness error and cylindrical error of spindle in precision grinder, we analyze the performances of hybrid bearing with deep-shallow oil chamber with FLUENT software. The influence of the different types of roundness error and the cylindrical error of spindle on the performance of the hybrid bearing varies with the change in bearing clearance. The results show that load capacity, power consumption and the highest temperature rise of the oil film in the bearing will increase with the increasing of error amplitude, but the variation rule in the bearing oil flow is opposite. The influences of the roundness errors of spindle on the performances of hybrid bearing in the spindle of precision grinder cannot be ignored in order to improve grinding precision.
2016, 35(6): 896-900.
doi: 10.13433/j.cnki.1003-8728.2016.0613
Abstract:
Two different typed shapes, including burr and fracture, can be formed in edges of workpiece under different cutting conditions. Also, fracture affects precision and performance of parts. A mechanical-heat coupling finite element model is established for simulating the forming process of burr and fracture based on the Normalized Cockroft & Latham ductile fracture criterion. According to the simulation results, it is found that the burrs forms due to the large plastic deformation of workpiece in the workpiece end surface, and the fracture forms due to the ductile fracture of workpiece in the machined surface. The critical parameters for fracture are obtained from the simulation results under different cutting conditions. It is found that the critical parameters obtained from the present model are close to the experimental results of cutting. The finite element model for burr and fracture provides an effective way for studying the forming mechanism of burr and fracture, and the simulation results provide the important reference for controlling the edge quality.
Two different typed shapes, including burr and fracture, can be formed in edges of workpiece under different cutting conditions. Also, fracture affects precision and performance of parts. A mechanical-heat coupling finite element model is established for simulating the forming process of burr and fracture based on the Normalized Cockroft & Latham ductile fracture criterion. According to the simulation results, it is found that the burrs forms due to the large plastic deformation of workpiece in the workpiece end surface, and the fracture forms due to the ductile fracture of workpiece in the machined surface. The critical parameters for fracture are obtained from the simulation results under different cutting conditions. It is found that the critical parameters obtained from the present model are close to the experimental results of cutting. The finite element model for burr and fracture provides an effective way for studying the forming mechanism of burr and fracture, and the simulation results provide the important reference for controlling the edge quality.
2016, 35(6): 901-905.
doi: 10.13433/j.cnki.1003-8728.2016.0614
Abstract:
The gear grinding allowances for gear measurement and tool setting are small. If only one or a few gear tooth space edges are measured or adjusted, some gear tooth space edges may be grinded heavily and other gear tooth space edges may not be grinded. Therefore we propose the method mentioned in the title. The angles of all (or some) of gear tooth space edges are measured. The optimal tool setting angle is calculated by the worst angles of gear tooth space start edge and gear tooth space end edge. Therefore, the most discrete gear tooth space start and end edges can be grinded with almost the same grinding allowance.
The gear grinding allowances for gear measurement and tool setting are small. If only one or a few gear tooth space edges are measured or adjusted, some gear tooth space edges may be grinded heavily and other gear tooth space edges may not be grinded. Therefore we propose the method mentioned in the title. The angles of all (or some) of gear tooth space edges are measured. The optimal tool setting angle is calculated by the worst angles of gear tooth space start edge and gear tooth space end edge. Therefore, the most discrete gear tooth space start and end edges can be grinded with almost the same grinding allowance.
2016, 35(6): 906-912.
doi: 10.13433/j.cnki.1003-8728.2016.0615
Abstract:
Due to the lack of basic data and the existence of uncertain information, such as the subjective assessment etc, it was difficult for the traditional reliability allocation theory to deal with uncertainties effectively, and the reliability allocation results were not reasonable as well. To solve this problem, a reliability allocation model combined with expert experiences and knowledge and the grey system theory was proposed. The core of the new model was to assess the relative failure relationship among units by using grey decision-making and gray relative analysis method, and then the reliability index was assigned to each unit according to the results obtained above. The advantages of the model were not only considering various factors affecting the reliability, but also reducing the error brought by the subjective assessment. Finally, the feasibility and accuracy of the new model were verified by case study.
Due to the lack of basic data and the existence of uncertain information, such as the subjective assessment etc, it was difficult for the traditional reliability allocation theory to deal with uncertainties effectively, and the reliability allocation results were not reasonable as well. To solve this problem, a reliability allocation model combined with expert experiences and knowledge and the grey system theory was proposed. The core of the new model was to assess the relative failure relationship among units by using grey decision-making and gray relative analysis method, and then the reliability index was assigned to each unit according to the results obtained above. The advantages of the model were not only considering various factors affecting the reliability, but also reducing the error brought by the subjective assessment. Finally, the feasibility and accuracy of the new model were verified by case study.
2016, 35(6): 913-917.
doi: 10.13433/j.cnki.1003-8728.2016.0616
Abstract:
Based on hybrid mechanism and strategies, a hybrid intelligent optimization algorithm(HGPA) is proposed by introducing the parallel evolution mechanism into genetic algorithm(GA) and particle swarm optimization(PSO). In this algorithm the individuals are divided into two small groups according to their fitness values and similarity. In the iteration, the sub-group of the top fitness values is evolved by GA, and the other sub-group is evolved by the PSO algorithm to achieve complementary advantages and value-added information. The evaluating standard of diversity is set to control the characteristics information of population and the searching space. The irregular parts packing experiment show that the HGPA can evenly control the evolution of individual local optimization and global search, and provide a new method of hybrid intelligent optimization.
Based on hybrid mechanism and strategies, a hybrid intelligent optimization algorithm(HGPA) is proposed by introducing the parallel evolution mechanism into genetic algorithm(GA) and particle swarm optimization(PSO). In this algorithm the individuals are divided into two small groups according to their fitness values and similarity. In the iteration, the sub-group of the top fitness values is evolved by GA, and the other sub-group is evolved by the PSO algorithm to achieve complementary advantages and value-added information. The evaluating standard of diversity is set to control the characteristics information of population and the searching space. The irregular parts packing experiment show that the HGPA can evenly control the evolution of individual local optimization and global search, and provide a new method of hybrid intelligent optimization.
2016, 35(6): 918-923.
doi: 10.13433/j.cnki.1003-8728.2016.0617
Abstract:
Based on the transient temperature distribution and the differential equation of nonsteady-state three-dimensional heat conduction, this paper establishes a 3D analytical model to predict grinding temperature. With the superposition of point source solution concerning the triangular heat source and the differential equation of nonsteady-state three-dimensional heat conduction in a moving semi-infinite solid, the paper obtains a three-dimensional nonsteady-state temperature equation, wherein the interdependence among grinding wheel, workpiece and coolant were described by two variable functions in the boundary condition. The sequential algorithm for inverse heat transfer is used to determine heat flux distribution. The thermal diffusivity in material is also considered. The integrals in the differential equation for nonsteady-state temperature are numerically evaluated using the adaptive Gauss-Kronrod quadrature, the steady-state solution of the temperature field is calculated, and the 3D analytical model of grinding temperature is built. All these are well coincided with the finite element model and the experimental measurement results.
Based on the transient temperature distribution and the differential equation of nonsteady-state three-dimensional heat conduction, this paper establishes a 3D analytical model to predict grinding temperature. With the superposition of point source solution concerning the triangular heat source and the differential equation of nonsteady-state three-dimensional heat conduction in a moving semi-infinite solid, the paper obtains a three-dimensional nonsteady-state temperature equation, wherein the interdependence among grinding wheel, workpiece and coolant were described by two variable functions in the boundary condition. The sequential algorithm for inverse heat transfer is used to determine heat flux distribution. The thermal diffusivity in material is also considered. The integrals in the differential equation for nonsteady-state temperature are numerically evaluated using the adaptive Gauss-Kronrod quadrature, the steady-state solution of the temperature field is calculated, and the 3D analytical model of grinding temperature is built. All these are well coincided with the finite element model and the experimental measurement results.
2016, 35(6): 924-928.
doi: 10.13433/j.cnki.1003-8728.2016.0618
Abstract:
Bond graph method is widely used in the modeling and simulation of mechatronic systems since it using a uniform manner to handle multiple forms of energy. Based on building bond graph models of electrical-fluid system, this paper constructs a signal acquisition net by installing multiple sensors, which can realize operation signal online collection, and deduce ARRs (Analytical Redundancy Relation) to calculate residual of physical system for FDI. Fault diagnosis experiments are performed on a vehicle steering system, and results indicate the correctness and practicality of designed FDI system.
Bond graph method is widely used in the modeling and simulation of mechatronic systems since it using a uniform manner to handle multiple forms of energy. Based on building bond graph models of electrical-fluid system, this paper constructs a signal acquisition net by installing multiple sensors, which can realize operation signal online collection, and deduce ARRs (Analytical Redundancy Relation) to calculate residual of physical system for FDI. Fault diagnosis experiments are performed on a vehicle steering system, and results indicate the correctness and practicality of designed FDI system.
2016, 35(6): 929-932.
doi: 10.13433/j.cnki.1003-8728.2016.0619
Abstract:
Combining dynamic fault probability with object oriented Bayesian network (OOBN), we propose a fault diagnosis model based on dynamic object oriented Bayesian network(DOOBN) with both the functional analysis and the failure mode effect analysis(FMEA). This methodology can adapt to construct fault diagnosis model of complex system. Considering the fault probability of component increases with the working time, the system function state is influenced by degradation of component reliability. This model is hierarchical and dynamic, it can be used to analyze failure propagation of, and it also facilitates the isolation of dependent failure. The proposed method was applied to ISG-engineand results suggest that this method can not only simplify the diagnosis model but also describe the actual state of the system.
Combining dynamic fault probability with object oriented Bayesian network (OOBN), we propose a fault diagnosis model based on dynamic object oriented Bayesian network(DOOBN) with both the functional analysis and the failure mode effect analysis(FMEA). This methodology can adapt to construct fault diagnosis model of complex system. Considering the fault probability of component increases with the working time, the system function state is influenced by degradation of component reliability. This model is hierarchical and dynamic, it can be used to analyze failure propagation of, and it also facilitates the isolation of dependent failure. The proposed method was applied to ISG-engineand results suggest that this method can not only simplify the diagnosis model but also describe the actual state of the system.
2016, 35(6): 933-938.
doi: 10.13433/j.cnki.1003-8728.2016.0620
Abstract:
Because there are wheel material cavities in a high-speed wheel, the three-dimensional wheel-rail contact model of a cavity in the wheel is established with the elastic-plastic finite element method. The non-linear constitutive relation of wheel material is employed in this model. The influence of cavity dimension, cavity location and wheel load on the stress and strain distributions of the wheel material is investigated. The calculation results show that the plastic deformation and stress concentration tend to occur in the wheel material close to the cavity. The stress and strain maximum values of the wheel material appear near the cavities which are located in the wheel's rim direction of about 160° and 340°. For the cavity whose dimension is less than 1 mm, the fatigue crack initiates easily when the cavity has a diameter of 0.1 mm. When the distance between wheel tread and cavity is less than 15 mm, its influence on the wheel's fatigue crack initiation is significant. As the wheel load increases, the stress and strain values of the wheel material around the cavity increase simultaneously.
Because there are wheel material cavities in a high-speed wheel, the three-dimensional wheel-rail contact model of a cavity in the wheel is established with the elastic-plastic finite element method. The non-linear constitutive relation of wheel material is employed in this model. The influence of cavity dimension, cavity location and wheel load on the stress and strain distributions of the wheel material is investigated. The calculation results show that the plastic deformation and stress concentration tend to occur in the wheel material close to the cavity. The stress and strain maximum values of the wheel material appear near the cavities which are located in the wheel's rim direction of about 160° and 340°. For the cavity whose dimension is less than 1 mm, the fatigue crack initiates easily when the cavity has a diameter of 0.1 mm. When the distance between wheel tread and cavity is less than 15 mm, its influence on the wheel's fatigue crack initiation is significant. As the wheel load increases, the stress and strain values of the wheel material around the cavity increase simultaneously.
2016, 35(6): 939-945.
doi: 10.13433/j.cnki.1003-8728.2016.0621
Abstract:
A novel method of obstacle avoidance and navigation is presented for mobile robots. Based on cloud models, the uncertainty of human being perception, reasoning and decision as well as the characteristics of human being collision avoidance and navigation are taken into account adequately. An anthropopathic decision making algorithm with the randomness meanwhile fuzziness is constructed based on cloud models, mainly includes the designs of rules for obstacles avoidance and object attracting, Gaussian cloud model of azimuth deviation, distance offset and steering angle, pass function. The method is possible to meet with the requirements of low computational cost and low precision for sensors as well as improvement of the artificial intelligence (AI). Theoretical analysis and simulation experiment show that the proposed method is effective.
A novel method of obstacle avoidance and navigation is presented for mobile robots. Based on cloud models, the uncertainty of human being perception, reasoning and decision as well as the characteristics of human being collision avoidance and navigation are taken into account adequately. An anthropopathic decision making algorithm with the randomness meanwhile fuzziness is constructed based on cloud models, mainly includes the designs of rules for obstacles avoidance and object attracting, Gaussian cloud model of azimuth deviation, distance offset and steering angle, pass function. The method is possible to meet with the requirements of low computational cost and low precision for sensors as well as improvement of the artificial intelligence (AI). Theoretical analysis and simulation experiment show that the proposed method is effective.
2016, 35(6): 946-950.
doi: 10.13433/j.cnki.1003-8728.2016.0622
Abstract:
The relationships between geometric parameters and camber are established based on structural and kinematic analysis of double wishbone suspension. Then, with MATLAB software, the relationships between camber curve shape and rod length configuration is obtained. Finally, a reasonable geometric configuration of double wishbone suspension is suggested. This work provides a reference for the design of double wishbone suspension with ideal camber variation.
The relationships between geometric parameters and camber are established based on structural and kinematic analysis of double wishbone suspension. Then, with MATLAB software, the relationships between camber curve shape and rod length configuration is obtained. Finally, a reasonable geometric configuration of double wishbone suspension is suggested. This work provides a reference for the design of double wishbone suspension with ideal camber variation.
2016, 35(6): 951-955.
doi: 10.13433/j.cnki.1003-8728.2016.0623
Abstract:
The classical cost rate model for age replacement policy is widely used to determine optimal preventive replacement age for important components. It is based on the renewal reward theorem and applicable for the case of infinite planning horizon. Recently, a new cost rate model was proposed and is applicable for the case of finite planning horizon, but its properties have not been studied. In this paper, a comparative analysis for these two models is carried out. After a brief introduction for the models, a detailed parametric study on the relationships between the Weibull shape parameter as well as cost ratio is conducted, and the optimal replacement age as well as the corresponding cost rate and the reliability obtained from the two models is obtaied. The main finding is that the preventive replacement age from the present model is always smaller than that from the classical model.
The classical cost rate model for age replacement policy is widely used to determine optimal preventive replacement age for important components. It is based on the renewal reward theorem and applicable for the case of infinite planning horizon. Recently, a new cost rate model was proposed and is applicable for the case of finite planning horizon, but its properties have not been studied. In this paper, a comparative analysis for these two models is carried out. After a brief introduction for the models, a detailed parametric study on the relationships between the Weibull shape parameter as well as cost ratio is conducted, and the optimal replacement age as well as the corresponding cost rate and the reliability obtained from the two models is obtaied. The main finding is that the preventive replacement age from the present model is always smaller than that from the classical model.
2016, 35(6): 956-960.
doi: 10.13433/j.cnki.1003-8728.2016.0624
Abstract:
The existing simulations of temperature field in deep small hole EDM are often implemented based on static flow fields or without considering flow fields, they can not reflect the actual machining process includes 6 MPa internal cooling liquid inside the tool-electrode when machining small holes between Ø0.3~Ø3 mm. The In order to reflect the real situation of Nickel-base superalloy Inconel718, the ANSYS Flotran CFD was used to simulate the process of deep small hole machining. First, a steady-state flow field analysis was conducted. Second, HGEN (Heat Generation) loads were loaded onto the model, and the transient analysis of temperature field was conducted, we can figure out that in steady-state flow field the temperature field is not symmetric but being blown by the flow. At the same time, part of the work-piece were be melted while copper tool-electrode is not affected by a single discharge. It is found that the reason for tool-electrode wears is the insufficient cooling in real machining process.
The existing simulations of temperature field in deep small hole EDM are often implemented based on static flow fields or without considering flow fields, they can not reflect the actual machining process includes 6 MPa internal cooling liquid inside the tool-electrode when machining small holes between Ø0.3~Ø3 mm. The In order to reflect the real situation of Nickel-base superalloy Inconel718, the ANSYS Flotran CFD was used to simulate the process of deep small hole machining. First, a steady-state flow field analysis was conducted. Second, HGEN (Heat Generation) loads were loaded onto the model, and the transient analysis of temperature field was conducted, we can figure out that in steady-state flow field the temperature field is not symmetric but being blown by the flow. At the same time, part of the work-piece were be melted while copper tool-electrode is not affected by a single discharge. It is found that the reason for tool-electrode wears is the insufficient cooling in real machining process.
2016, 35(6): 961-967.
doi: 10.13433/j.cnki.1003-8728.2016.0625
Abstract:
For the manufacturing of crowned gears, the surface coordinate equation of logarithmic crowned helical gears with high contact ratio was established. Based on the contact mechanics model,programs were developed in Matlab to compute the contact stress and the Mises stress field inside subsurface layer at any engaging position. The relative fatigue life of modified gears was also evaluated on the basis of the fatigue life model of Ioannides and Harris. The results show that the logarithmic modification can eliminate the edge effect of tooth surfaces and prolong the fatigue life of the helical gears; on a certain contact line of helical tooth surface, the position with higher contact stress has larger amount of logarithmic modification, which ensures uniform distribution of contact stress on the whole tooth flank after modification.
For the manufacturing of crowned gears, the surface coordinate equation of logarithmic crowned helical gears with high contact ratio was established. Based on the contact mechanics model,programs were developed in Matlab to compute the contact stress and the Mises stress field inside subsurface layer at any engaging position. The relative fatigue life of modified gears was also evaluated on the basis of the fatigue life model of Ioannides and Harris. The results show that the logarithmic modification can eliminate the edge effect of tooth surfaces and prolong the fatigue life of the helical gears; on a certain contact line of helical tooth surface, the position with higher contact stress has larger amount of logarithmic modification, which ensures uniform distribution of contact stress on the whole tooth flank after modification.
2016, 35(6): 968-974.
doi: 10.13433/j.cnki.1003-8728.2016.0626
Abstract:
According to the dynamic scheduling of dual resource constrained job-shop, a three layer dynamic scheduling system, including analysis on dynamic disturbance, assessment on dynamic disturbance and the dynamic scheduling method, is constructed in terms of the local time window scheduling. According to the minimization and modification of old scheduling scheme, we propose a mixed dynamic scheduling algorithm based on the chromosomal reduction mechanism and the scheduling optimization of local job in stages. The outstanding application effect of the dynamic scheduling system based on the local time window scheduling and the dynamic scheduling algorithm which effectively reduce the influence of dynamic disturbances are validated by using the simulation results at last.
According to the dynamic scheduling of dual resource constrained job-shop, a three layer dynamic scheduling system, including analysis on dynamic disturbance, assessment on dynamic disturbance and the dynamic scheduling method, is constructed in terms of the local time window scheduling. According to the minimization and modification of old scheduling scheme, we propose a mixed dynamic scheduling algorithm based on the chromosomal reduction mechanism and the scheduling optimization of local job in stages. The outstanding application effect of the dynamic scheduling system based on the local time window scheduling and the dynamic scheduling algorithm which effectively reduce the influence of dynamic disturbances are validated by using the simulation results at last.
2016, 35(6): 975-979.
doi: 10.13433/j.cnki.1003-8728.2016.0627
Abstract:
The kinematic relationship of A8 area of AVEN(Axial-symmetric Vectoring Exhaust Nozzle) is studied for the accurate adjustment and control of its motion and to meet the requirements of the best coefficient of expansion ratio. The irregular A8 area is formed with the back-end of the convergence pieces and the seals, and it is mathematically represented by an inscribed circle. It is indicated that the method of approximate representation is feasible based on error analysis. A kinematics model of the A8 area is built according to the given conditions, namely the cambered surface of the convergence piece comeing across its both ends. With the relatively simple analytical functions for the related variables,the complicated iteration is omitted, which simplifies the solving process. Finally, the relationship between the A8 area and the advance amount of the A8 actuators is obtianed. Simulation results indicate that the function is in accordance with the measured data and the accuracy of the result is about 96%.
The kinematic relationship of A8 area of AVEN(Axial-symmetric Vectoring Exhaust Nozzle) is studied for the accurate adjustment and control of its motion and to meet the requirements of the best coefficient of expansion ratio. The irregular A8 area is formed with the back-end of the convergence pieces and the seals, and it is mathematically represented by an inscribed circle. It is indicated that the method of approximate representation is feasible based on error analysis. A kinematics model of the A8 area is built according to the given conditions, namely the cambered surface of the convergence piece comeing across its both ends. With the relatively simple analytical functions for the related variables,the complicated iteration is omitted, which simplifies the solving process. Finally, the relationship between the A8 area and the advance amount of the A8 actuators is obtianed. Simulation results indicate that the function is in accordance with the measured data and the accuracy of the result is about 96%.
2016, 35(6): 980-984.
doi: 10.13433/j.cnki.1003-8728.2016.0628
Abstract:
In order to evaluate the fatigue load dispersion of aircraft engines, assuming the mixing and fixed frequency task, and considering the influence of technique differences among aviators, we construct a matrix aggregate of loads based on the flight profiles, and build a model for fatigue dispersion coefficients to correlate fatigue load dispersion of aircraft engines. The validity of the present model was validated with the example analysis and computer simulation via Monte Carlo method. It was shown that accumulative fatigue loads of aircraft engines in life period submit to normal distribution. Fatigue load dispersion increases with the increasing of load dispersion of load aggregate, whereas if decreases with the increasing of lifetime. Fatigue dispersion coefficients correlating fatigue load dispersion of aircraft engines increases with the increasing of load dispersion of load aggregate and the requirement of reliability, whereas if decreases with increasing of lifetime.
In order to evaluate the fatigue load dispersion of aircraft engines, assuming the mixing and fixed frequency task, and considering the influence of technique differences among aviators, we construct a matrix aggregate of loads based on the flight profiles, and build a model for fatigue dispersion coefficients to correlate fatigue load dispersion of aircraft engines. The validity of the present model was validated with the example analysis and computer simulation via Monte Carlo method. It was shown that accumulative fatigue loads of aircraft engines in life period submit to normal distribution. Fatigue load dispersion increases with the increasing of load dispersion of load aggregate, whereas if decreases with the increasing of lifetime. Fatigue dispersion coefficients correlating fatigue load dispersion of aircraft engines increases with the increasing of load dispersion of load aggregate and the requirement of reliability, whereas if decreases with increasing of lifetime.
