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RSS2014 Vol. 33, No. 1
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2014, 33(1): 1-7.
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Abstract:
The study of the power branch gear transmission system vibration inherent characteristic is very important in the design process,for the gear-mesh frequencies should keep away from the natural frequencies. Based on the rotor-bearing system dynamics,coupling the bending-torsion vibration,the dynamic characteristics equations of power four-path gear transmission were deduced by means of the solving free vibration characteristic equation,and the first 14 orders natural frequencies and the modes of vibration in the system,and the first 8 orders inherent characteristic in the system uncoupling state. The analysis results show in the following: 1) the symmetry of the system structure results in part of the rotor vibration modes symmetry; 2) the modes of the system performance for two types: one type is mainly some or other rotor vibration,other rotors amplitudes are very small,another type is complex multi-rotor bending-torsion vibration; 3) the coupled bending-torsion between the rotors have a greater impact on the system natural frequencies and modes,the bending-torsion vibration must be considered in the study of the power branch gear transmission system vibration inherent characteristic.
The study of the power branch gear transmission system vibration inherent characteristic is very important in the design process,for the gear-mesh frequencies should keep away from the natural frequencies. Based on the rotor-bearing system dynamics,coupling the bending-torsion vibration,the dynamic characteristics equations of power four-path gear transmission were deduced by means of the solving free vibration characteristic equation,and the first 14 orders natural frequencies and the modes of vibration in the system,and the first 8 orders inherent characteristic in the system uncoupling state. The analysis results show in the following: 1) the symmetry of the system structure results in part of the rotor vibration modes symmetry; 2) the modes of the system performance for two types: one type is mainly some or other rotor vibration,other rotors amplitudes are very small,another type is complex multi-rotor bending-torsion vibration; 3) the coupled bending-torsion between the rotors have a greater impact on the system natural frequencies and modes,the bending-torsion vibration must be considered in the study of the power branch gear transmission system vibration inherent characteristic.
2014, 33(1): 8-12.
Abstract:
In order to improve the adaptability of the harvester on the small terraces,the articulated diamondshaped frame is introduced to design of the harvester,and the structural optimization design of the harvester is also implemented. First,the initial finite element model of frame structure to meet the assembly layout and the actual driving requirements is established,based on the structure of the rhombus harvester frame and the mechanical characteristics,and the stress distributions are calculated in a variety of typical operating conditions. Based on the results of analyses,the sectional dimensions of the frame component is optimized,and the lightweight designs of articulated rhombus frame is realized. This design method is capable of reducing the design cycle,and the cost.
In order to improve the adaptability of the harvester on the small terraces,the articulated diamondshaped frame is introduced to design of the harvester,and the structural optimization design of the harvester is also implemented. First,the initial finite element model of frame structure to meet the assembly layout and the actual driving requirements is established,based on the structure of the rhombus harvester frame and the mechanical characteristics,and the stress distributions are calculated in a variety of typical operating conditions. Based on the results of analyses,the sectional dimensions of the frame component is optimized,and the lightweight designs of articulated rhombus frame is realized. This design method is capable of reducing the design cycle,and the cost.
2014, 33(1): 13-17.
Abstract:
Closed-loop constraint equations of Stephenson-Ⅲ linkage mechanisms are established based on the Con-formal Geometric Algebra (CGA), by using Euler formula.The closed-loop equations are expressed as compound exponential form. Mutual relationships between various parameters in the formula and vectors in con formal space are described.Depending on given input, input-output equations are derived to solve the position of the link mechanism. The value of Jacobian matrix determinant equals to 0, so that the discriminative formulas of the dead-center positions are derived and the dead-center position solutions are gained. Finally, the effectiveness and accuracy of this method are verified by contrasting with traditional numerical methods.
Closed-loop constraint equations of Stephenson-Ⅲ linkage mechanisms are established based on the Con-formal Geometric Algebra (CGA), by using Euler formula.The closed-loop equations are expressed as compound exponential form. Mutual relationships between various parameters in the formula and vectors in con formal space are described.Depending on given input, input-output equations are derived to solve the position of the link mechanism. The value of Jacobian matrix determinant equals to 0, so that the discriminative formulas of the dead-center positions are derived and the dead-center position solutions are gained. Finally, the effectiveness and accuracy of this method are verified by contrasting with traditional numerical methods.
2014, 33(1): 18-21.
Abstract:
Based on bearing load signals, the transient torque fault of a multi-support rotor system is identified in this paper. Bearing load signals are collected directly by the load sensors, and the bearing load sensitivity matrix based on the incentive of torque is applied. The transient torque value produced by magnetic powder brake can be identified with the proposed method. Compared with the actual value measured by torque transducer, the identification error is in the allowable range.The proposed method for identifying transient torque is feasible.
Based on bearing load signals, the transient torque fault of a multi-support rotor system is identified in this paper. Bearing load signals are collected directly by the load sensors, and the bearing load sensitivity matrix based on the incentive of torque is applied. The transient torque value produced by magnetic powder brake can be identified with the proposed method. Compared with the actual value measured by torque transducer, the identification error is in the allowable range.The proposed method for identifying transient torque is feasible.
2014, 33(1): 22-26.
Abstract:
A backstepping sliding mode control strategy was proposed for the control of nonlinear dynamic system ofa robot manipulator with flexible joints with external disturbance. The controller took the output angle vector of motor as control variables of joint's subsystem to realize the tracking trajectory control with angle vector of virtual machine, while the trajectory error was eliminated by comprehensive integral item in inversion stabilization function.The actual output torque was calculated thus the output angle of motor can track the virtual control volume, and the influence of system uncertainty was eliminated by design an adaptive sliding mode variable structure controller. The stability of the system and the convergence of trajectory tracking error were certified based on Lyapunov stability theory.
A backstepping sliding mode control strategy was proposed for the control of nonlinear dynamic system ofa robot manipulator with flexible joints with external disturbance. The controller took the output angle vector of motor as control variables of joint's subsystem to realize the tracking trajectory control with angle vector of virtual machine, while the trajectory error was eliminated by comprehensive integral item in inversion stabilization function.The actual output torque was calculated thus the output angle of motor can track the virtual control volume, and the influence of system uncertainty was eliminated by design an adaptive sliding mode variable structure controller. The stability of the system and the convergence of trajectory tracking error were certified based on Lyapunov stability theory.
2014, 33(1): 27-31.
Abstract:
For the purpose of making the most effective compacting operation of intelligent vibratory roller under different compaction stages, this paper analyzes the relationship between the vibrating wheel, rack displacement and different parameters, through establishing the four-degree of freedom dynamic model of vibrating wheel-soil body under the coupling operating condition. Besides, by optimizing the calculated parameters, the best vibration frequency and vibration angle are obtained so that the compacting is the biggest and also does not cause jumping vibra-tion, which provides the numerical basis for the parameter optimization of intelligent vibratory roller under different compaction stages. The result indicates that the degree of soil body compactness will reach maximum when the vi-bration frequency of vibratory roller keeps in the range of 1.29～1.39 times of soil body's second order frequency.
For the purpose of making the most effective compacting operation of intelligent vibratory roller under different compaction stages, this paper analyzes the relationship between the vibrating wheel, rack displacement and different parameters, through establishing the four-degree of freedom dynamic model of vibrating wheel-soil body under the coupling operating condition. Besides, by optimizing the calculated parameters, the best vibration frequency and vibration angle are obtained so that the compacting is the biggest and also does not cause jumping vibra-tion, which provides the numerical basis for the parameter optimization of intelligent vibratory roller under different compaction stages. The result indicates that the degree of soil body compactness will reach maximum when the vi-bration frequency of vibratory roller keeps in the range of 1.29～1.39 times of soil body's second order frequency.
2014, 33(1): 32-36.
Abstract:
Key factors that affect luffing stability of a common folding-boom arm system are investigated though dy-namics simulation and analysis, and an optimized control strategy is proposed to achieve stable luffing process in this paper. The arm system movement in luffing process is described. The jittering of the working point at beginningand end moment of the luffing process is analyzed by simulation. Motion characteristics and displacement curves on the selected mark point are gained. The simulation results indicate that the main factor that affects arm luffing stabil-ity lies on the action synchronization of the cylinders that drive the middle arm. An optimized control strategy is pro-posed through parameter adjusting simulations. The field test results have shown that the arm luffing stability is clearly improved, and the demand on hydraulic cylinder's motion precision is greatly reduced.
Key factors that affect luffing stability of a common folding-boom arm system are investigated though dy-namics simulation and analysis, and an optimized control strategy is proposed to achieve stable luffing process in this paper. The arm system movement in luffing process is described. The jittering of the working point at beginningand end moment of the luffing process is analyzed by simulation. Motion characteristics and displacement curves on the selected mark point are gained. The simulation results indicate that the main factor that affects arm luffing stabil-ity lies on the action synchronization of the cylinders that drive the middle arm. An optimized control strategy is pro-posed through parameter adjusting simulations. The field test results have shown that the arm luffing stability is clearly improved, and the demand on hydraulic cylinder's motion precision is greatly reduced.
Rolling Element Bearings Fault Diagnosis Method Based on CITD and Homomorphic Filtering Demodulation
2014, 33(1): 37-42.
Abstract:
Aiming at the non-stationary characteristics of a bearing fault vibration signal and the disadvantage of In-trinsic Time-scale Decomposition (ITD) method, an improved ITD method combining the Cubic polynomial-based Intrinsic Time-scale Decomposition (CITD) and the homomorphic filtering demodulation was proposed. In this ap-proach, the CITD method was applied to decompose the vibration signal into a finite number of proper rotation com-ponents, then the correlation coefficients were used to select the proper rotation(PＲ) components best representing the fault information and to reconstruct the signal. Finally, the fault characteristics was extracted from the recon-structed signal by homomorphic filtering demodulation. The effectiveness of the present method was verified by anal-ysis of simulation signals and engineering examples of bearing fault diagnosis.
Aiming at the non-stationary characteristics of a bearing fault vibration signal and the disadvantage of In-trinsic Time-scale Decomposition (ITD) method, an improved ITD method combining the Cubic polynomial-based Intrinsic Time-scale Decomposition (CITD) and the homomorphic filtering demodulation was proposed. In this ap-proach, the CITD method was applied to decompose the vibration signal into a finite number of proper rotation com-ponents, then the correlation coefficients were used to select the proper rotation(PＲ) components best representing the fault information and to reconstruct the signal. Finally, the fault characteristics was extracted from the recon-structed signal by homomorphic filtering demodulation. The effectiveness of the present method was verified by anal-ysis of simulation signals and engineering examples of bearing fault diagnosis.
2014, 33(1): 43-47.
Abstract:
Owing to the frequent failure of milling drum, the necessity appears that the various rules of the milling stress during the surface milling process and the effects that the milling elements have on the milling stress should be researched. The working principle of milling drum was analyzed. Finite element model of the process that milling drum mills asphalt pavement was established in ABAQUS according to the material model based on Johnson-cook constitutive relation and fracture criterion. Then the whole milling process was simulated, and the variation process of milling force when the milling drum mills asphalt pavement with different speeds, feed rates, and cutting depths.The result was concluded: cutting stress increases with cutting speed and the growth rate is about 0.022 to 0.026MPa/(r/min); Cutting stress increases with a larger cutting depth. The growth rate is about 0. 414 to0.493 MPa/mm; Conversely, Cutting stress decreases when feed speed increases. The growth rate is about－0.037 2 to-0.036 6 MPa/(mm/s).
Owing to the frequent failure of milling drum, the necessity appears that the various rules of the milling stress during the surface milling process and the effects that the milling elements have on the milling stress should be researched. The working principle of milling drum was analyzed. Finite element model of the process that milling drum mills asphalt pavement was established in ABAQUS according to the material model based on Johnson-cook constitutive relation and fracture criterion. Then the whole milling process was simulated, and the variation process of milling force when the milling drum mills asphalt pavement with different speeds, feed rates, and cutting depths.The result was concluded: cutting stress increases with cutting speed and the growth rate is about 0.022 to 0.026MPa/(r/min); Cutting stress increases with a larger cutting depth. The growth rate is about 0. 414 to0.493 MPa/mm; Conversely, Cutting stress decreases when feed speed increases. The growth rate is about－0.037 2 to-0.036 6 MPa/(mm/s).
2014, 33(1): 48-52.
Abstract:
To further simplify the structure of traditional hydraulic system and improve its working efficiency, a dig-ital hydraulic actuator system with inner circulation was designed, in which the power unit, actuator and control el-ement are entirely integrated. The operational principle of the system is analyzed and all kinds of parameters of the system are determined. Simulation model of the system is established and simulations are performed by using AMES-im software. The results show that the designed system has a great advantage in the situation with limited space and weight, and it is applicable for hydraulic systems of low speed and low or medium pressure.
To further simplify the structure of traditional hydraulic system and improve its working efficiency, a dig-ital hydraulic actuator system with inner circulation was designed, in which the power unit, actuator and control el-ement are entirely integrated. The operational principle of the system is analyzed and all kinds of parameters of the system are determined. Simulation model of the system is established and simulations are performed by using AMES-im software. The results show that the designed system has a great advantage in the situation with limited space and weight, and it is applicable for hydraulic systems of low speed and low or medium pressure.
2014, 33(1): 53-56.
Abstract:
The method to balance computational precision and time-consuming by adaptive encryption in the process of finite element analysis is discussed. Building the model of helical gear and divide the mesh of it, as well as com-pleting finite element analysis, the value about tensile stress of the tooth root's midpoint is calculated, using Matlab software to make curve fitting of the value is done, and get the relationship of tensile stress of the tooth root's mid-point and density of mesh and the width of gear, tensile stress of the tooth root's midpoint is the important parameter to measure whether adaptive encryption is appropriate, then use the range of chimobi to complete adaptive encryp-tion, and make sure that time-consuming is short and the result of finite element analysis is accurate.
The method to balance computational precision and time-consuming by adaptive encryption in the process of finite element analysis is discussed. Building the model of helical gear and divide the mesh of it, as well as com-pleting finite element analysis, the value about tensile stress of the tooth root's midpoint is calculated, using Matlab software to make curve fitting of the value is done, and get the relationship of tensile stress of the tooth root's mid-point and density of mesh and the width of gear, tensile stress of the tooth root's midpoint is the important parameter to measure whether adaptive encryption is appropriate, then use the range of chimobi to complete adaptive encryp-tion, and make sure that time-consuming is short and the result of finite element analysis is accurate.
2014, 33(1): 57-64.
Abstract:
A constraint transformation method is put forward to solve geometric constraint system with closed-loops for 3D assembly design. Firstly, the equivalence analysis method is employed to eliminate the pseudo closed-loops of 3D geometric constraint system, whose geometric constraint graph will be decomposed into independent-edge sub-graph, independent-loop subgraph, and coupling-loop subgraph with the block-finding algorithm of undirected graph. Then, the screw theory is utilized to recognize the kinematic pair from the assembly geometric constraint combination, and map the geometric constraint graph with closed-loops to the kinematic pair graph. Based on the topological structure analysis of kinematic pair graph, some cut-constraints are determined to transform the closed-loop structure of geometric constraint graph into the open-loop structure, and the relative coordinate representation of constraint system is also established, so as to convert the whole iteration solution of geometric constraint system to the partial iteration solution of some cut-constraints and relative coordinates. The proposed method can reduced the size of constraint equations and variables that have to be solved simultaneously so that its stability and efficiency can be improved dramatically. Meanwhile, the proposed method can ensure the correctness of solution result via introducing additional direction constraint.
A constraint transformation method is put forward to solve geometric constraint system with closed-loops for 3D assembly design. Firstly, the equivalence analysis method is employed to eliminate the pseudo closed-loops of 3D geometric constraint system, whose geometric constraint graph will be decomposed into independent-edge sub-graph, independent-loop subgraph, and coupling-loop subgraph with the block-finding algorithm of undirected graph. Then, the screw theory is utilized to recognize the kinematic pair from the assembly geometric constraint combination, and map the geometric constraint graph with closed-loops to the kinematic pair graph. Based on the topological structure analysis of kinematic pair graph, some cut-constraints are determined to transform the closed-loop structure of geometric constraint graph into the open-loop structure, and the relative coordinate representation of constraint system is also established, so as to convert the whole iteration solution of geometric constraint system to the partial iteration solution of some cut-constraints and relative coordinates. The proposed method can reduced the size of constraint equations and variables that have to be solved simultaneously so that its stability and efficiency can be improved dramatically. Meanwhile, the proposed method can ensure the correctness of solution result via introducing additional direction constraint.
2014, 33(1): 65-70.
Abstract:
The present processing technology for honing net-lines and influence factors are introduced in this paper.Simulation analysis on reciprocating reversing acceleration for honing machine is studied and the effect of accelera-tion change on the main honing machine parameters and quality of reticulate pattern are revealed. According to re-quirements for the actual production, the best reciprocating reversing acceleration is obtained based on the analysis.It is concluded that the bigger honing reversing acceleration, the smaller area of circular arc transition, the higher quality of honing reticulate pattern.
The present processing technology for honing net-lines and influence factors are introduced in this paper.Simulation analysis on reciprocating reversing acceleration for honing machine is studied and the effect of accelera-tion change on the main honing machine parameters and quality of reticulate pattern are revealed. According to re-quirements for the actual production, the best reciprocating reversing acceleration is obtained based on the analysis.It is concluded that the bigger honing reversing acceleration, the smaller area of circular arc transition, the higher quality of honing reticulate pattern.
2014, 33(1): 71-81.
Abstract:
Market competition analysis of customer requirements (CRs) is a necessary step to determine final im-portance ratings of CRs more precisely, and its effectiveness will directly affect the accuracy of building house of quality (HOQ). Firstly, based on asymmetric triangular fuzzy utility preferences for each competitive product offered by each customer, a new method to establish fuzzy competitive evaluation matrixes of CRs corresponding toeach customer was proposed. Secondly, according to a principle of fuzzy deviation between two asymmetric triangular fuzzy numbers, a single－objective optimization model which aims at maximizing the total similarities of fuzzy competitive evaluations was constructed by using fuzzy competitive evaluation matrixes. Finally, this model was resolved by using Lagrange function, and then normalized competitive priority ratings of CRs were obtained.The proposed approach was illustrated to its feasibility and superiority with a help of an example of vibrating feeder produced by a mechanical engineering enterprise and compared with the information entropy one.
Market competition analysis of customer requirements (CRs) is a necessary step to determine final im-portance ratings of CRs more precisely, and its effectiveness will directly affect the accuracy of building house of quality (HOQ). Firstly, based on asymmetric triangular fuzzy utility preferences for each competitive product offered by each customer, a new method to establish fuzzy competitive evaluation matrixes of CRs corresponding toeach customer was proposed. Secondly, according to a principle of fuzzy deviation between two asymmetric triangular fuzzy numbers, a single－objective optimization model which aims at maximizing the total similarities of fuzzy competitive evaluations was constructed by using fuzzy competitive evaluation matrixes. Finally, this model was resolved by using Lagrange function, and then normalized competitive priority ratings of CRs were obtained.The proposed approach was illustrated to its feasibility and superiority with a help of an example of vibrating feeder produced by a mechanical engineering enterprise and compared with the information entropy one.
2014, 33(1): 82-87.
Abstract:
In order to solve manufacturing enterprise differentiation of demanding for process planning system, a project of structured multi-view mode for process planning was presented. By means of studying multi-view process planning mode based on structural-model-driven, multi-view show mode of process data, interactive technology be-tween multi-view, model structure of binary body set and multi-view process data interchange standards were put forward so as to realize process planning of structural-model-driven and XML (Extensible Markup Language, XML)data to exchange process data between multi-view, guarantee veracity of process data. An effective method for low flexibility of process planning system was provided.
In order to solve manufacturing enterprise differentiation of demanding for process planning system, a project of structured multi-view mode for process planning was presented. By means of studying multi-view process planning mode based on structural-model-driven, multi-view show mode of process data, interactive technology be-tween multi-view, model structure of binary body set and multi-view process data interchange standards were put forward so as to realize process planning of structural-model-driven and XML (Extensible Markup Language, XML)data to exchange process data between multi-view, guarantee veracity of process data. An effective method for low flexibility of process planning system was provided.
2014, 33(1): 88-92.
Abstract:
The remanufacturing clearing technology is one of the key technologies to manufacture. The technology of ultrasonic clearing for remanufacturing was put forward in this paper and the influencing factors of ultrasonic clearing were expatiated. A new type of ultrasonic cleaner A was made and the clearing contrast experiments have been done, the cleaning efficiencies under different conditions were measured. The experimental results show that the clearing efficiency reached to 100% for using ultrasonic cleaner A in 3.5 min on the temperature of 60 ℃. The clearing examples of the clearing technology applied in waste bridge shell have obtained a good effect.
The remanufacturing clearing technology is one of the key technologies to manufacture. The technology of ultrasonic clearing for remanufacturing was put forward in this paper and the influencing factors of ultrasonic clearing were expatiated. A new type of ultrasonic cleaner A was made and the clearing contrast experiments have been done, the cleaning efficiencies under different conditions were measured. The experimental results show that the clearing efficiency reached to 100% for using ultrasonic cleaner A in 3.5 min on the temperature of 60 ℃. The clearing examples of the clearing technology applied in waste bridge shell have obtained a good effect.
2014, 33(1): 93-97.
Abstract:
The solution of packing layout problem has been proved to be NPC problem, the result of solving the problem is the optimal solution which constraint conditions. Actually, the way of packing layout widely used in ma-chinery manufacturing, industry, large scale integrated circuit design, transportation, combination machine tools, aerospace, etc. The layout design of Mechanical product has extensive application background, excellent mechanical layout design will get good mechanical properties. Generally, people using heuristic algorithm and intel-ligent algorithm to solve the problems of layout with modeling. This paper according to the mechanical product lay-out, describe the way of solving the layout problem and the coding method of triple group, and through an example to verify the validity of triple group coding in the mechanical product layout.
The solution of packing layout problem has been proved to be NPC problem, the result of solving the problem is the optimal solution which constraint conditions. Actually, the way of packing layout widely used in ma-chinery manufacturing, industry, large scale integrated circuit design, transportation, combination machine tools, aerospace, etc. The layout design of Mechanical product has extensive application background, excellent mechanical layout design will get good mechanical properties. Generally, people using heuristic algorithm and intel-ligent algorithm to solve the problems of layout with modeling. This paper according to the mechanical product lay-out, describe the way of solving the layout problem and the coding method of triple group, and through an example to verify the validity of triple group coding in the mechanical product layout.
2014, 33(1): 98-103.
Abstract:
In this paper, active control of sound radiated from an underwater finite elastic cylindrical shell by using secondary cylindrical-ringed sound source is investigated. First, the interaction radiation impedance between the primary cylindrical shell and secondary sound source is calculated. Then considering fluid-structure interaction effects and using quadratic optimal theory, the optimal excitation force of secondary source is derived with the mini-mization of the radiated sound power. Finally, the far-filed sound pressure is observed and compared before and af-ter control. The results show that the noise radiated from the finite elastic cylindrical shell can be controlled by using secondary cylindrical ringed sound source, the effects becomes poor with the increase of the distance between the primary cylindrical shells and secondary source, and the secondary excitation position also have an significant influ-ence on active sound control.
In this paper, active control of sound radiated from an underwater finite elastic cylindrical shell by using secondary cylindrical-ringed sound source is investigated. First, the interaction radiation impedance between the primary cylindrical shell and secondary sound source is calculated. Then considering fluid-structure interaction effects and using quadratic optimal theory, the optimal excitation force of secondary source is derived with the mini-mization of the radiated sound power. Finally, the far-filed sound pressure is observed and compared before and af-ter control. The results show that the noise radiated from the finite elastic cylindrical shell can be controlled by using secondary cylindrical ringed sound source, the effects becomes poor with the increase of the distance between the primary cylindrical shells and secondary source, and the secondary excitation position also have an significant influ-ence on active sound control.
2014, 33(1): 104-108.
Abstract:
In order to minimize the simple duplication of effort, reduce development cost and improve efficiency in the design and development of electromagnetic valves, a digital prototype based on Visual C++ was established by means of parametric simulations. The digital prototype can monitor and manipulate the entire process of design and development of the electromagnetic valves. This process includes engineering calculation for structural parameters, parametric 3D-modeling by Pro/E, and calculation for flow resistance by CFD, electromagnetic distribution by Maxwell software and structural strength verification by ANSYS software. Finally, the measured data of the single-seal direct-acting electromagnetic valve and data cited from references are used to verify the performance simulation results of the digital prototype. The verification demonstrates that the digital prototype developed in thre present study has good reliability.
In order to minimize the simple duplication of effort, reduce development cost and improve efficiency in the design and development of electromagnetic valves, a digital prototype based on Visual C++ was established by means of parametric simulations. The digital prototype can monitor and manipulate the entire process of design and development of the electromagnetic valves. This process includes engineering calculation for structural parameters, parametric 3D-modeling by Pro/E, and calculation for flow resistance by CFD, electromagnetic distribution by Maxwell software and structural strength verification by ANSYS software. Finally, the measured data of the single-seal direct-acting electromagnetic valve and data cited from references are used to verify the performance simulation results of the digital prototype. The verification demonstrates that the digital prototype developed in thre present study has good reliability.
2014, 33(1): 109-112.
Abstract:
The spiral fluidized automatic cleaning technology was Organic combination of spiral wire cleaning and the liquid-solid fluidized cleaning technology, which could effectively prevent descaling, strengthen the automatic on-line heat transfer. The simulation experiment has been devised by spiral fluidization technology, the sloping baf-fle structure with the cross section upward tilt decreasing in the heat exchange tube had been put forward, which ef-fectively solved the technical problems of fluidized particles in the realization of the uniform distribution of heat ex-change tube. with the average diameter particles was 3 mm and the flow respectively was 8.8 m 3/h, 10 m 3/h, 12 m 3/h, the distribution of the fluidized particles and velocity had been measured and the average fluidized parti-cles sedimentation velocity was 0.3～0.4 m/s, the uniform distribution of heat exchange tube box structure had been optimized , which realized natural cycle of fluidized particles in high-speed situation, liquid-solid separation objec-tive structure.
The spiral fluidized automatic cleaning technology was Organic combination of spiral wire cleaning and the liquid-solid fluidized cleaning technology, which could effectively prevent descaling, strengthen the automatic on-line heat transfer. The simulation experiment has been devised by spiral fluidization technology, the sloping baf-fle structure with the cross section upward tilt decreasing in the heat exchange tube had been put forward, which ef-fectively solved the technical problems of fluidized particles in the realization of the uniform distribution of heat ex-change tube. with the average diameter particles was 3 mm and the flow respectively was 8.8 m 3/h, 10 m 3/h, 12 m 3/h, the distribution of the fluidized particles and velocity had been measured and the average fluidized parti-cles sedimentation velocity was 0.3～0.4 m/s, the uniform distribution of heat exchange tube box structure had been optimized , which realized natural cycle of fluidized particles in high-speed situation, liquid-solid separation objec-tive structure.
2014, 33(1): 113-116.
Abstract:
The stiffness variation of air spring has a great impact on the analysis and dynamic modeling of vehicle suspension system, while the experimental characteristics curve of the air spring provided by the manufacturer cannot reflect its property. The state equation of ideal gas was used to establish the polynomial equation for the spring stiffness and deformations. The dynamic characteristics curve of air spring was obtained by finite element simulation and the stiffness property was fitted with polynomial. Based on the simulation models of suspension dynamics, thee ffect of different initial spring height on the stiffness variation property curve of air spring was studied in the condi-tion of constant pressure. The theoretical stiffness curve was compared with the simulated one. The results show that the stiffness values of loaded air spring in actual conditions are larger than the theoretical values and the actual stiff-ness variation curve is not to the same as the curve shifted by the deformation in the theoretical formulation.
The stiffness variation of air spring has a great impact on the analysis and dynamic modeling of vehicle suspension system, while the experimental characteristics curve of the air spring provided by the manufacturer cannot reflect its property. The state equation of ideal gas was used to establish the polynomial equation for the spring stiffness and deformations. The dynamic characteristics curve of air spring was obtained by finite element simulation and the stiffness property was fitted with polynomial. Based on the simulation models of suspension dynamics, thee ffect of different initial spring height on the stiffness variation property curve of air spring was studied in the condi-tion of constant pressure. The theoretical stiffness curve was compared with the simulated one. The results show that the stiffness values of loaded air spring in actual conditions are larger than the theoretical values and the actual stiff-ness variation curve is not to the same as the curve shifted by the deformation in the theoretical formulation.
2014, 33(1): 117-121.
Abstract:
In order to analyze the lateral torque transferring of an active differential and its influence on the per-formance of vehicle drivability, a state space model of active differential, which includes the nonlinear tire model and all the inertias of driving axle, is developed to reflect its dynamic responses and kinematic characteristics. Sim-ulation experiments of the active differential are carried out on a virtual straight slope test road to validate the model and performance of active differential by using MATLAB/Simulink. The simulation results demonstrate that the ac-tive differential generates direct yaw moment by lateral torque transferring between left and right tires when the vehi-cle accelerates on a virtual straight slope road, and this device contributes to stability performance improvement at the cost of small drivability decline.
In order to analyze the lateral torque transferring of an active differential and its influence on the per-formance of vehicle drivability, a state space model of active differential, which includes the nonlinear tire model and all the inertias of driving axle, is developed to reflect its dynamic responses and kinematic characteristics. Sim-ulation experiments of the active differential are carried out on a virtual straight slope test road to validate the model and performance of active differential by using MATLAB/Simulink. The simulation results demonstrate that the ac-tive differential generates direct yaw moment by lateral torque transferring between left and right tires when the vehi-cle accelerates on a virtual straight slope road, and this device contributes to stability performance improvement at the cost of small drivability decline.
2014, 33(1): 122-126.
Abstract:
It is difficult to get a combination of optimal parameters and shorten design time because there are many factors affecting the drawing forming, the forming principle by using experience, orthogonal experiment and analysis of variance are obtained for the drawing forming. On this basis of those rsults, the drawing function is evaluated by using comprehensive weighted grading and the processing parameters is optimized by using the objective function and complex optimization method. The optimization results show that the synthetic weighted mark method and the complex algorithm is reliable so as to provide a reasonable and advanced way for CAE sheet forming analysis of opti-mal parameter settings.
It is difficult to get a combination of optimal parameters and shorten design time because there are many factors affecting the drawing forming, the forming principle by using experience, orthogonal experiment and analysis of variance are obtained for the drawing forming. On this basis of those rsults, the drawing function is evaluated by using comprehensive weighted grading and the processing parameters is optimized by using the objective function and complex optimization method. The optimization results show that the synthetic weighted mark method and the complex algorithm is reliable so as to provide a reasonable and advanced way for CAE sheet forming analysis of opti-mal parameter settings.
2014, 33(1): 127-132.
Abstract:
In order to improve the corrosion and wear resistance of new 7A85 aluminum alloy, in-situ ceramic coat-ings on the new 7A85 aluminum alloy were fabricated by micro-arc oxidation (MAO), and sealed with rare earth cerium solution. The surface morphology and phase composition of ceramic coatings were investigated by SEM and XＲD. Salt spray tests and electrochemical measurement techniques were used to investigate the corrosion behavior of ceramic coatings. The tribological properties of ceramic coatings were carried out under dry sliding using ball-on-disc test rig. The results indicate that the ceramic coating on the new 7A85 aluminum alloy is mainly composed of α-Al 2O 3 and γ-Al 2 O 3phase, the ceramic coatings were uniform and compact after cerium salt sealing treatment.The micro-arc oxidation treatment can effectively improve the corrosion resistance of new 7A85 aluminum alloy in3.5% Na Cl solution, making the corrosion rate decrease by 1 order of magnitude. The sealing treatment by rare earth cerium salt on the MAO coatings can further improve the corrosion resistance of the ceramic coatings with corrosion rate reducing by another 1 order of magnitude. The MAO treatment can improve the wear resistance of new 7A85 alloy remarkably, with the volumetric wear rate decrease from 4.56×10－3mm 3 /(N·m) to 5.73×10－4mm 3 /(N·m). The sealing treatment by rare earth cerium salt on the ceramic coatings decreases the friction coefficient, but has no signif-icant influence on the wear rate.
In order to improve the corrosion and wear resistance of new 7A85 aluminum alloy, in-situ ceramic coat-ings on the new 7A85 aluminum alloy were fabricated by micro-arc oxidation (MAO), and sealed with rare earth cerium solution. The surface morphology and phase composition of ceramic coatings were investigated by SEM and XＲD. Salt spray tests and electrochemical measurement techniques were used to investigate the corrosion behavior of ceramic coatings. The tribological properties of ceramic coatings were carried out under dry sliding using ball-on-disc test rig. The results indicate that the ceramic coating on the new 7A85 aluminum alloy is mainly composed of α-Al 2O 3 and γ-Al 2 O 3phase, the ceramic coatings were uniform and compact after cerium salt sealing treatment.The micro-arc oxidation treatment can effectively improve the corrosion resistance of new 7A85 aluminum alloy in3.5% Na Cl solution, making the corrosion rate decrease by 1 order of magnitude. The sealing treatment by rare earth cerium salt on the MAO coatings can further improve the corrosion resistance of the ceramic coatings with corrosion rate reducing by another 1 order of magnitude. The MAO treatment can improve the wear resistance of new 7A85 alloy remarkably, with the volumetric wear rate decrease from 4.56×10－3mm 3 /(N·m) to 5.73×10－4mm 3 /(N·m). The sealing treatment by rare earth cerium salt on the ceramic coatings decreases the friction coefficient, but has no signif-icant influence on the wear rate.
2014, 33(1): 133-139.
Abstract:
The material identification of impacted plate with varied boundary condition is studied. Two subjective e-valuation experiments are designed, in which sounds are synthesized using a physical model of ball-plate collisions.Dissimilarity evaluation of sounds coming from impacted plate with different material and boundary condition are ob-tained in the first experiment, and perceptual space characteristics of sounds are inferred from multidimensional scaling of dissimilarity rating. In the second experiment, the material identification of sound sets which are syn the-sized with gradually varied material properties of plates are carried out, and we measured listeners' ability to exploit damping under different boundary conditions. The results showed that listeners have the ability to identify material by using sounds coming from different boundary conditions, and identification results have great relations with sub-jective evaluation experimental methods and listeners' ability to exploit damping varied with boundary conditions.
The material identification of impacted plate with varied boundary condition is studied. Two subjective e-valuation experiments are designed, in which sounds are synthesized using a physical model of ball-plate collisions.Dissimilarity evaluation of sounds coming from impacted plate with different material and boundary condition are ob-tained in the first experiment, and perceptual space characteristics of sounds are inferred from multidimensional scaling of dissimilarity rating. In the second experiment, the material identification of sound sets which are syn the-sized with gradually varied material properties of plates are carried out, and we measured listeners' ability to exploit damping under different boundary conditions. The results showed that listeners have the ability to identify material by using sounds coming from different boundary conditions, and identification results have great relations with sub-jective evaluation experimental methods and listeners' ability to exploit damping varied with boundary conditions.
2014, 33(1): 140-145.
Abstract:
In order to improve the tribological behavior in aviation kerosene, plasma nitriding layer in the Ti6Al4Vbase alloy were fabricated by using a plasma glow-discharge surface technique. The morphology, microstructure and microhardness depth distribution of the plasma nitriding layer were studied. The tribological properties of the Ti6Al4Vbase alloy, nitriding layer and 5CrMnMo steel sliding with GCr15 steel or QSn4-3 copper alloy counterparts in aviation kerosene were comparatively studied. The effect of the roughness on the sliding wear behavior was discussed. The re-sults indicated that the nitriding modified layer with polishing treatment not only reduce the wear volume of Ti6Al4Vbase alloy, but also enhance the wear resistance of the counterparts due to the high microhardness of nitriding layer.The nitriding modified layer has better tribological behavior than that of 5CrMnMo steel. It is also found that the wear volume loss of the counterparts is proportional to the value of roughness of nitriding modified layer, which is related directly to the ploughing wear between micro convex bodies of the layer and counterparts.
In order to improve the tribological behavior in aviation kerosene, plasma nitriding layer in the Ti6Al4Vbase alloy were fabricated by using a plasma glow-discharge surface technique. The morphology, microstructure and microhardness depth distribution of the plasma nitriding layer were studied. The tribological properties of the Ti6Al4Vbase alloy, nitriding layer and 5CrMnMo steel sliding with GCr15 steel or QSn4-3 copper alloy counterparts in aviation kerosene were comparatively studied. The effect of the roughness on the sliding wear behavior was discussed. The re-sults indicated that the nitriding modified layer with polishing treatment not only reduce the wear volume of Ti6Al4Vbase alloy, but also enhance the wear resistance of the counterparts due to the high microhardness of nitriding layer.The nitriding modified layer has better tribological behavior than that of 5CrMnMo steel. It is also found that the wear volume loss of the counterparts is proportional to the value of roughness of nitriding modified layer, which is related directly to the ploughing wear between micro convex bodies of the layer and counterparts.
2014, 33(1): 146-150.
Abstract:
Parachute recovery is one of important ways to landing of Unmanned Aerial Vehicle (UAV for short), the effectiveness of a recovery system needs to be verified by full scale aircraft landing test. According to the dynam-ics characteristics of small parachute landing recovery UAV, a new platform and test system was established for landing recovery test. In this test platform, some key technical problems such as mechanical system design and test system building were solved. The successful implementation of the test shows that, the test system is stable and reli-able, and it can be used for UAV landing during landing gear load, energy absorption test, aircraft strength verifi-cation and vibration response of structural performance test. And the platform and test system provides some techni-cal references for other types of aircraft landing test.
Parachute recovery is one of important ways to landing of Unmanned Aerial Vehicle (UAV for short), the effectiveness of a recovery system needs to be verified by full scale aircraft landing test. According to the dynam-ics characteristics of small parachute landing recovery UAV, a new platform and test system was established for landing recovery test. In this test platform, some key technical problems such as mechanical system design and test system building were solved. The successful implementation of the test shows that, the test system is stable and reli-able, and it can be used for UAV landing during landing gear load, energy absorption test, aircraft strength verifi-cation and vibration response of structural performance test. And the platform and test system provides some techni-cal references for other types of aircraft landing test.
2014, 33(1): 151-156.
Abstract:
To keep the adjusted pose of the wing/vertical fin supported by flexible fixture and hold it reliably is a difficult problem during the process of dotting and finishing etc. One kind of auxiliary device based on pneumatic, hydraulic and vacuum techniques was designed to solve this problem. The load bearing capacity and key parameters of the device are analyzed and tested. The results show that the auxiliary clamping devices can improve the wing/vertical fin ability to resist external load and enhance the stability of the system. The present study provides a new method of stable clamping for big parts adjusted by flexible fixture.
To keep the adjusted pose of the wing/vertical fin supported by flexible fixture and hold it reliably is a difficult problem during the process of dotting and finishing etc. One kind of auxiliary device based on pneumatic, hydraulic and vacuum techniques was designed to solve this problem. The load bearing capacity and key parameters of the device are analyzed and tested. The results show that the auxiliary clamping devices can improve the wing/vertical fin ability to resist external load and enhance the stability of the system. The present study provides a new method of stable clamping for big parts adjusted by flexible fixture.
