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RSS2014 Vol. 33, No. 9
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2014, 33(9): 1281-1286.
doi: 10.13433/j.cnki.1003-8728.2014.0901
PDF 488KB
Abstract:
The design domain of lath-shaped structure have a large length-width ratio,so it is difficult to obtain a clear and periodic topology configuration using conventional topology optimization algorithms. Using variable density theory and solid isotropic microstructures with penalization(SIMP) model,this paper presents a periodic topology optimization method under stiffness constraint condition. The mathematical models for periodic topology optimization is built,in which the volume of structure is taken as objective function and relative densities of elements are taken as design variables. In order to obtain a topology structure which possesses periodicity,an additional constraint condition is introduced into the mathematical model. The iterative formula of virtual sub-domain design variables is deduced by taking the advantage of optimality criteria method and Lagrange multiplier is calculated using stiffness constraint. A filtering function is imported in order to solve the checkerboard and mesh-dependent problems. A clear and periodic topology configuration of a cantilever beam is obtained by the proposed method. The results show that the periodic topology configuration with good consistency cab be achieved when the number of sub-domain is different. This classical example proves that it is feasible and effective for applying variable density method to achieve periodic topology optimization.
The design domain of lath-shaped structure have a large length-width ratio,so it is difficult to obtain a clear and periodic topology configuration using conventional topology optimization algorithms. Using variable density theory and solid isotropic microstructures with penalization(SIMP) model,this paper presents a periodic topology optimization method under stiffness constraint condition. The mathematical models for periodic topology optimization is built,in which the volume of structure is taken as objective function and relative densities of elements are taken as design variables. In order to obtain a topology structure which possesses periodicity,an additional constraint condition is introduced into the mathematical model. The iterative formula of virtual sub-domain design variables is deduced by taking the advantage of optimality criteria method and Lagrange multiplier is calculated using stiffness constraint. A filtering function is imported in order to solve the checkerboard and mesh-dependent problems. A clear and periodic topology configuration of a cantilever beam is obtained by the proposed method. The results show that the periodic topology configuration with good consistency cab be achieved when the number of sub-domain is different. This classical example proves that it is feasible and effective for applying variable density method to achieve periodic topology optimization.
2014, 33(9): 1287-1292.
doi: 10.13433/j.cnki.1003-8728.2014.0902
Abstract:
There are large numbers of welds on cranes' lattice booms with notably complicated force conditions.The calculation accuracy of fatigue life for the K nodes of crane is low based on the linear Palmgren-Miner(PM)rule. A new stress spectrum acquisition method named"measured simulated compared statistics"integrated strategy of crane K-nodes is proposed based on the virtual prototype technology. The method can reduce the work amount and cost significantly of the spectra acquisition working. The Huffman non-linear cumulative damage theory is applied first time to calculate the fatigue life for the K-nodes of crane. By setting different initial damage conditions,the initial damage suggestion value is proposed that the calculation result of the fatigue life can be moderately conservative. The fatigue test indicates that the calculation accuracy of the non-linear method is higher than the PM rule. As the Huffman non-linear cumulative damage theory requires the cyclic stress-strain curve and the constant amplitude strain-life curve,it could therefore be more suitable for engineering applications.
There are large numbers of welds on cranes' lattice booms with notably complicated force conditions.The calculation accuracy of fatigue life for the K nodes of crane is low based on the linear Palmgren-Miner(PM)rule. A new stress spectrum acquisition method named"measured simulated compared statistics"integrated strategy of crane K-nodes is proposed based on the virtual prototype technology. The method can reduce the work amount and cost significantly of the spectra acquisition working. The Huffman non-linear cumulative damage theory is applied first time to calculate the fatigue life for the K-nodes of crane. By setting different initial damage conditions,the initial damage suggestion value is proposed that the calculation result of the fatigue life can be moderately conservative. The fatigue test indicates that the calculation accuracy of the non-linear method is higher than the PM rule. As the Huffman non-linear cumulative damage theory requires the cyclic stress-strain curve and the constant amplitude strain-life curve,it could therefore be more suitable for engineering applications.
2014, 33(9): 1293-1297.
doi: 10.13433/j.cnki.1003-8728.2014.0903
Abstract:
The model of hydragas suspension is that the output force is expressed with a polynomial structure of displacement and speed. Conventional least square method can not determine the significant polynomial terms. In order to solve this problem,the err-reduction-ratio(ERR) structure-selection technique is proposed to select the significant polynomial terms and estimate the unknown parameters in the model. The hydragas suspension of a armored vehicle is used to illustrate the feasibility of the proposed method. The results show that the proposed strategy is effective in modeling hydragas suspension with concise polynomial structure and accurate parameters.
The model of hydragas suspension is that the output force is expressed with a polynomial structure of displacement and speed. Conventional least square method can not determine the significant polynomial terms. In order to solve this problem,the err-reduction-ratio(ERR) structure-selection technique is proposed to select the significant polynomial terms and estimate the unknown parameters in the model. The hydragas suspension of a armored vehicle is used to illustrate the feasibility of the proposed method. The results show that the proposed strategy is effective in modeling hydragas suspension with concise polynomial structure and accurate parameters.
2014, 33(9): 1298-1303.
doi: 10.13433/j.cnki.1003-8728.2014.0904
Abstract:
The parameter,calculation method and characterization of body-seat interface pressure distribution are expounded. The body pressure distribution parameter is divided into basic parameter,static parameter and dynamic parameter. Static parameter includes seat pressure distribution(SPD%),circular pressure gradient(GC) and transverse pressure gradient(GT). Dynamic parameter includes dynamic seat pressure distribution(DSPD%),pressure change rate root-mean-square(Pcrms) and area pressure change rate(aPcrms). By testing on the different surface molding and different hardness of seat foam,the result shows that there is a liner relation between GC,GT,SPD% and seat comfort. The smaller value GCor GTis,the more comfortable of ischial tuberosity area occupant feels. The smaller value SPD% is,the more comfortable of overall buttocks occupant feels. The moderate concave surface molding is more comfort than flat surface molding. The maximum pressure(Pm) and SPD% can characterize the hardness of seat foam obviously. Hard seat foam has higher Pmand SPD% value. But SPD% can't reflect the hardness of seat foam if the weight of occupant is too large.
The parameter,calculation method and characterization of body-seat interface pressure distribution are expounded. The body pressure distribution parameter is divided into basic parameter,static parameter and dynamic parameter. Static parameter includes seat pressure distribution(SPD%),circular pressure gradient(GC) and transverse pressure gradient(GT). Dynamic parameter includes dynamic seat pressure distribution(DSPD%),pressure change rate root-mean-square(Pcrms) and area pressure change rate(aPcrms). By testing on the different surface molding and different hardness of seat foam,the result shows that there is a liner relation between GC,GT,SPD% and seat comfort. The smaller value GCor GTis,the more comfortable of ischial tuberosity area occupant feels. The smaller value SPD% is,the more comfortable of overall buttocks occupant feels. The moderate concave surface molding is more comfort than flat surface molding. The maximum pressure(Pm) and SPD% can characterize the hardness of seat foam obviously. Hard seat foam has higher Pmand SPD% value. But SPD% can't reflect the hardness of seat foam if the weight of occupant is too large.
Effect of the Joints Clearance on The Precision of Bottom Dead Center for Multi-rod Mechanical Press
2014, 33(9): 1304-1308.
doi: 10.13433/j.cnki.1003-8728.2014.0905
Abstract:
Press processing precision becomes more and more important in Modern processing industry. Based on the computer simulation software ADAMS,the dynamic modeling of multi-rod mechanical press was founded to investigate how the joints clearance for multi-rod mechanical press influence the repeat accuracy of bottom dead center. The impacts between the clearance were simulated using the theory of impulse function to reveal whether the kinematic pairs with clearance have affection on the repeat precision of the bottom dead center(BDC) for multi-rod mechanical press. The results show that the joints clearance influences the repeat precision. The fluctuating values increase and the mean values location of BDC drift downward with the rising rotary speed. Comparing with the experimental data,it is concluded that the fluctuating values is greatly influenced by the clearance between kinematic pairs,but drift distance of BDC caused by the clearance is small.
Press processing precision becomes more and more important in Modern processing industry. Based on the computer simulation software ADAMS,the dynamic modeling of multi-rod mechanical press was founded to investigate how the joints clearance for multi-rod mechanical press influence the repeat accuracy of bottom dead center. The impacts between the clearance were simulated using the theory of impulse function to reveal whether the kinematic pairs with clearance have affection on the repeat precision of the bottom dead center(BDC) for multi-rod mechanical press. The results show that the joints clearance influences the repeat precision. The fluctuating values increase and the mean values location of BDC drift downward with the rising rotary speed. Comparing with the experimental data,it is concluded that the fluctuating values is greatly influenced by the clearance between kinematic pairs,but drift distance of BDC caused by the clearance is small.
2014, 33(9): 1309-1313.
doi: 10.13433/j.cnki.1003-8728.2014.0906
Abstract:
In order to improve the accuracy of ink preset and optimize the structure of the ink key,the mathematical model of the ink flow fields with different parameters conditions is established. Numerical simulations are performed to obtian the velocity distribution of flow fields at ink key opening side. And the variation law of fountain flow velocity and pressure is analyzed under the condition of variable speed and opening degree. The results show that the relationship among ink key opening degree,ink roller speed and the flow rate of ink can be accurately determined. This study can provide theoretical basis for the accurate control of ink flow during actual work.
In order to improve the accuracy of ink preset and optimize the structure of the ink key,the mathematical model of the ink flow fields with different parameters conditions is established. Numerical simulations are performed to obtian the velocity distribution of flow fields at ink key opening side. And the variation law of fountain flow velocity and pressure is analyzed under the condition of variable speed and opening degree. The results show that the relationship among ink key opening degree,ink roller speed and the flow rate of ink can be accurately determined. This study can provide theoretical basis for the accurate control of ink flow during actual work.
2014, 33(9): 1314-1318.
doi: 10.13433/j.cnki.1003-8728.2014.0907
Abstract:
Firstly the reaction-diffusion model is coupled with finite element method to establish a simple mathematical model of bone remodeling. Secondly the bone remodeling process is translated into material formation and absorption process by using the pixel element adding and removing techniques,and a new bionic algorithm for topology optimization of two dimensional continuum structures is proposed. Michell type bridge structure,widely used as example in continuum structural topology optimization,is carried out by using presented bionic algorithm and the results are compared with other topology optimization techniques to confirm the validity of the proposed method. Finally,a long cantilever beam structure under two different boundary conditions is carried out by using presented algorithm; regularity and symmetry topology are obtained. This result further explains the feasibility and reliability of the proposed bionic algorithm.
Firstly the reaction-diffusion model is coupled with finite element method to establish a simple mathematical model of bone remodeling. Secondly the bone remodeling process is translated into material formation and absorption process by using the pixel element adding and removing techniques,and a new bionic algorithm for topology optimization of two dimensional continuum structures is proposed. Michell type bridge structure,widely used as example in continuum structural topology optimization,is carried out by using presented bionic algorithm and the results are compared with other topology optimization techniques to confirm the validity of the proposed method. Finally,a long cantilever beam structure under two different boundary conditions is carried out by using presented algorithm; regularity and symmetry topology are obtained. This result further explains the feasibility and reliability of the proposed bionic algorithm.
2014, 33(9): 1319-1323.
doi: 10.13433/j.cnki.1003-8728.2014.0908
Abstract:
The acceleration sensor can pick up the acceleration signals of the vibration,and the vibration velocity and displacement can be obtained through the numerical integration. The integral error in the numerical integration exists and increases rapidly with the test time increase so that it leads to velocity and displacement signal serious deviation from the actual results. By numerical integration error analysis,a separation method is designed based on the integration error of Empirical Mode Decomposition,which is an effective way to solve this problem. The effectiveness of this method is verified by simulation and experiment.
The acceleration sensor can pick up the acceleration signals of the vibration,and the vibration velocity and displacement can be obtained through the numerical integration. The integral error in the numerical integration exists and increases rapidly with the test time increase so that it leads to velocity and displacement signal serious deviation from the actual results. By numerical integration error analysis,a separation method is designed based on the integration error of Empirical Mode Decomposition,which is an effective way to solve this problem. The effectiveness of this method is verified by simulation and experiment.
2014, 33(9): 1324-1328.
doi: 10.13433/j.cnki.1003-8728.2014.0909
Abstract:
An efficient evidence-theory model considering the dependence among evidence variables is presented,and the application in the structural reliability analysis is discussed. The ellipsoidal model and an efficient analytical method to the structural reliability analysis is introduced based on the evidence-theory to improve the accuracy and efficiency of the analysis. Combining the ellipsoidal model with the marginal basic probability assignments(BPA) of all the parameters,a joint BPA structure can be constructed. Then,an efficient calculation method is presented. In the present method,the uncertainty domain can be divided into two parts(reliable domain and the domain to be determined) by finding the most probable point of failure(MPP). The present approach reduces the number of focal elements which need to calculate,and greatly improves the efficiency of structural reliability analysis based on the evidence-theory. A mathematic example is investigated to demonstrate the effectiveness of the present method.
An efficient evidence-theory model considering the dependence among evidence variables is presented,and the application in the structural reliability analysis is discussed. The ellipsoidal model and an efficient analytical method to the structural reliability analysis is introduced based on the evidence-theory to improve the accuracy and efficiency of the analysis. Combining the ellipsoidal model with the marginal basic probability assignments(BPA) of all the parameters,a joint BPA structure can be constructed. Then,an efficient calculation method is presented. In the present method,the uncertainty domain can be divided into two parts(reliable domain and the domain to be determined) by finding the most probable point of failure(MPP). The present approach reduces the number of focal elements which need to calculate,and greatly improves the efficiency of structural reliability analysis based on the evidence-theory. A mathematic example is investigated to demonstrate the effectiveness of the present method.
2014, 33(9): 1329-1334.
doi: 10.13433/j.cnki.1003-8728.2014.0910
Abstract:
In order to investigate dynamic characteristics of a thin seam shearer,the rigid-flexible coupled model of shearer cutting unit was established. According to the major technical parameters of shearer and the arrangement of cutting pick,the transient load of cutting pick under actual work condition was calculated out and applied in the model of shearer cutting unit. The dynamic characteristics of shearer cutting unit were obtained through the numerical simulation. It was found that the drum vibration is more intense,shell out of the side neck has large dynamic stresses. The modal parameter and the easily excited modal shapes of the system were recognized,and found that the drum and shell have high mode kinetic energy. According to analysis results,the design of the shell structure was optimized,and mechanical properties and the reliability of the cutting unit shell were significantly improved.
In order to investigate dynamic characteristics of a thin seam shearer,the rigid-flexible coupled model of shearer cutting unit was established. According to the major technical parameters of shearer and the arrangement of cutting pick,the transient load of cutting pick under actual work condition was calculated out and applied in the model of shearer cutting unit. The dynamic characteristics of shearer cutting unit were obtained through the numerical simulation. It was found that the drum vibration is more intense,shell out of the side neck has large dynamic stresses. The modal parameter and the easily excited modal shapes of the system were recognized,and found that the drum and shell have high mode kinetic energy. According to analysis results,the design of the shell structure was optimized,and mechanical properties and the reliability of the cutting unit shell were significantly improved.
2014, 33(9): 1434-1438.
doi: 10.13433/j.cnki.1003-8728.2014.0931
Abstract:
By using a model experiment rig of dual-rotor system of aeroengine under base movements,the dual-rotor system vibration when an aircraft is in hovering,pitching and rolling motion is simulated,the influence over dynamic characteristics of the dual rotor system under maneuvering conditions is studied. The experimental results show that the transient aircraft additional centrifugal force and gyroscopic moment generated in the internal rotor and the external rotor in rolling and pitching motion have a great influence on the system transient vibration amplitude,the dynamic response influence characteristics of the dual-rotor of aeroengine under different flight conditions is summarized.
2014, 33(9): 1335-1339.
doi: 10.13433/j.cnki.1003-8728.2014.0911
Abstract:
To improve the reliability of diamond roller rotation system in CNC gear grinding machine,the set pair analysis theory is introduced into the process of the fault tree analysis of diamond roller rotation system in this paper. A new reliability model was established,which combined the theory of set pair analysis with the fault tree analysis method. The logic gate set to operator commonly used in the model and the basic analysis process were presented. The failure probability interval of diamond roller rotation system was calculated and the improvement measure against invalidation was put forward. Results show that the method effectively reduces the possibility of system turn failure and improves the reliability of CNC gear grinding machine.
To improve the reliability of diamond roller rotation system in CNC gear grinding machine,the set pair analysis theory is introduced into the process of the fault tree analysis of diamond roller rotation system in this paper. A new reliability model was established,which combined the theory of set pair analysis with the fault tree analysis method. The logic gate set to operator commonly used in the model and the basic analysis process were presented. The failure probability interval of diamond roller rotation system was calculated and the improvement measure against invalidation was put forward. Results show that the method effectively reduces the possibility of system turn failure and improves the reliability of CNC gear grinding machine.
2014, 33(9): 1340-1344.
doi: 10.13433/j.cnki.1003-8728.2014.0912
Abstract:
In order to extract faint fault information from the complicated vibration singals of rolling bearing,a novel bearing fault diagnosis method is presented based on the principles of local mean decomposition(LMD) and difference spectrum of singular value. In this method,the original nonstationary fault signals of rolling bearing were decomposed by LMD and a group of product functions(PFs) were obtained; However,it is difficult to extract fault frequencies due to strong background noise. To identify the fault pattern,a Hankel matrix of the PFs was constructed and decomposed with singular value decomposition(SVD). Accordingly,difference spectrum of singular values was also obtained. On the basis of difference spectrum theory,the filtered and reconstructed signal of the PF component was analyzed by using envelope spectrum and the acurate fault frequency can be obtained. The effectiveness of the proposed method was demonstrated with the simulated data and the actual signals measured in the inner race of a fault rolling bearing,and the present method had a good prospect for its application in rolling bearing fault diagnosis.
In order to extract faint fault information from the complicated vibration singals of rolling bearing,a novel bearing fault diagnosis method is presented based on the principles of local mean decomposition(LMD) and difference spectrum of singular value. In this method,the original nonstationary fault signals of rolling bearing were decomposed by LMD and a group of product functions(PFs) were obtained; However,it is difficult to extract fault frequencies due to strong background noise. To identify the fault pattern,a Hankel matrix of the PFs was constructed and decomposed with singular value decomposition(SVD). Accordingly,difference spectrum of singular values was also obtained. On the basis of difference spectrum theory,the filtered and reconstructed signal of the PF component was analyzed by using envelope spectrum and the acurate fault frequency can be obtained. The effectiveness of the proposed method was demonstrated with the simulated data and the actual signals measured in the inner race of a fault rolling bearing,and the present method had a good prospect for its application in rolling bearing fault diagnosis.
Morlet Wavelet Transform-based Signal De-noising and its Application in Bearing Condition Monitoring
2014, 33(9): 1345-1349.
doi: 10.13433/j.cnki.1003-8728.2014.0913
Abstract:
In order to track degradational trend of bearing performance using shock feature hidden in the vibration signal with strong background noise,a condition monitoring method integrating Morlet wavelet transform and timedomain features extraction was proposed. The de-noising effectiveness under Morlet wavelet filtering was evaluated by spectral kurtosis. With the compounding information constructed from filtered signal,the time-domain feature parameters were extracted. The proposed method was applied to the bearing full lifetime vibration datasets,and the results show that the feature trends can reflect the degradational process of bearing condition and the bearing operational safety can be ensured by the followed caution from incipient fault detection.
In order to track degradational trend of bearing performance using shock feature hidden in the vibration signal with strong background noise,a condition monitoring method integrating Morlet wavelet transform and timedomain features extraction was proposed. The de-noising effectiveness under Morlet wavelet filtering was evaluated by spectral kurtosis. With the compounding information constructed from filtered signal,the time-domain feature parameters were extracted. The proposed method was applied to the bearing full lifetime vibration datasets,and the results show that the feature trends can reflect the degradational process of bearing condition and the bearing operational safety can be ensured by the followed caution from incipient fault detection.
2014, 33(9): 1350-1353.
doi: 10.13433/j.cnki.1003-8728.2014.0914
Abstract:
According to the situation that the lack of research on ultrasonic guided wave pipe profile reconstruction of defect,a defect profile reconstruction method is proposed based on least square support vector machine(LSSVM) with improved particle swarm optimization(PSO) algorithms. The echo signals of defects with different sizes are obtained experimentally and by using ANSYS software. By using the echo signal data as input and the two dimensional(2D) profile reconstruction data as output,the nonlinear mapping is established to. achieve the 2D profile reconstruction of pipe defect with axial width and radial depth. The reconstructed profile is compared with those obtained by the radial basis function neural network method and LS-SVM method with general PSO algorithm.The experimental results show that the present method has stronger generalization ability and can be used as a reference method for visualized defect detection.
According to the situation that the lack of research on ultrasonic guided wave pipe profile reconstruction of defect,a defect profile reconstruction method is proposed based on least square support vector machine(LSSVM) with improved particle swarm optimization(PSO) algorithms. The echo signals of defects with different sizes are obtained experimentally and by using ANSYS software. By using the echo signal data as input and the two dimensional(2D) profile reconstruction data as output,the nonlinear mapping is established to. achieve the 2D profile reconstruction of pipe defect with axial width and radial depth. The reconstructed profile is compared with those obtained by the radial basis function neural network method and LS-SVM method with general PSO algorithm.The experimental results show that the present method has stronger generalization ability and can be used as a reference method for visualized defect detection.
2014, 33(9): 1354-1358.
doi: 10.13433/j.cnki.1003-8728.2014.0915
Abstract:
In order to investigate the influence of laser energy on the melting and plasticizing process,a theoretical model for the melting process of polymer material was presented,which is based on the optics-thermal interaction of CO2 laser to polymer material. According to the energy conservation and thermal physics,the mathematical models of laser parameters and temperature was analyzed under CO2 laser irradiating,and the effect relationship between laser parameters and melting depth of typical polymer material was discussed with the methods of numerical calculation and experiment. The obtained results demonstrate that there is the surface and depth melting process characteristic,the reasonably laser processing parameters has the biggest effect for polymer material melting process from outside to inside,and the theoretical results of melting depth fit well with experiments data. Accordingly,the model and formula can provide a theory foundation to control plasticizing and processing of polymer material under CO2 laser irradiating.
In order to investigate the influence of laser energy on the melting and plasticizing process,a theoretical model for the melting process of polymer material was presented,which is based on the optics-thermal interaction of CO2 laser to polymer material. According to the energy conservation and thermal physics,the mathematical models of laser parameters and temperature was analyzed under CO2 laser irradiating,and the effect relationship between laser parameters and melting depth of typical polymer material was discussed with the methods of numerical calculation and experiment. The obtained results demonstrate that there is the surface and depth melting process characteristic,the reasonably laser processing parameters has the biggest effect for polymer material melting process from outside to inside,and the theoretical results of melting depth fit well with experiments data. Accordingly,the model and formula can provide a theory foundation to control plasticizing and processing of polymer material under CO2 laser irradiating.
2014, 33(9): 1359-1363.
doi: 10.13433/j.cnki.1003-8728.2014.0916
Abstract:
A new geometric model for the quartic generalized C-B閦ier surface with multiple shape parameters is constructed by using the basis functions 1,t,t2,sint,cost. The proposed generalized C-B閦ier surface not only inherit the outstanding properties of the B閦ier surface,but also have a good performance on adjusting their shapes by changing shape control parameters. To tackle the problem that the engineering complex surfaces can not be constructed by using a single surface,the continuity condition of quartic generalized C-B閦ier surface with shape parameter are investigated. Based on the analysis of the basis functions,the conditions of G0 and G1continuity between two adjacent quartic generalized C-B閦ier surface are proposed. In addition,the application of the quartic generalized C-B閦ier surface design is discussed.
A new geometric model for the quartic generalized C-B閦ier surface with multiple shape parameters is constructed by using the basis functions 1,t,t2,sint,cost. The proposed generalized C-B閦ier surface not only inherit the outstanding properties of the B閦ier surface,but also have a good performance on adjusting their shapes by changing shape control parameters. To tackle the problem that the engineering complex surfaces can not be constructed by using a single surface,the continuity condition of quartic generalized C-B閦ier surface with shape parameter are investigated. Based on the analysis of the basis functions,the conditions of G0 and G1continuity between two adjacent quartic generalized C-B閦ier surface are proposed. In addition,the application of the quartic generalized C-B閦ier surface design is discussed.
2014, 33(9): 1364-1367.
doi: 10.13433/j.cnki.1003-8728.2014.0917
Abstract:
Aiming at the problems existing in gear box fault diagnosis such that difficult to detecting,strong subjectivity and low accuracy,a fault diagnosis method based on particle swarm optimization(PSO) algorithm and support vector machine(SVM) is proposed. In this method the time domain analysis and frequency domain analysis are conducted to get the characteristic value of vibration signals,and the SVM is used for pattern recognition and fault classification of the characteristic parameters of gearbox,and PSO is introduced in the optimization of SVM parameters. A typical gearbox fault diagnosis model is established and the experimental results show that the method can classify different gear box fault type accurately and the reliability of the gear box fault diagnosis is effectively improved.
Aiming at the problems existing in gear box fault diagnosis such that difficult to detecting,strong subjectivity and low accuracy,a fault diagnosis method based on particle swarm optimization(PSO) algorithm and support vector machine(SVM) is proposed. In this method the time domain analysis and frequency domain analysis are conducted to get the characteristic value of vibration signals,and the SVM is used for pattern recognition and fault classification of the characteristic parameters of gearbox,and PSO is introduced in the optimization of SVM parameters. A typical gearbox fault diagnosis model is established and the experimental results show that the method can classify different gear box fault type accurately and the reliability of the gear box fault diagnosis is effectively improved.
2014, 33(9): 1368-1372.
doi: 10.13433/j.cnki.1003-8728.2014.0918
Abstract:
This paper mainly introduces an integrated electro-hydraulic testing system for excavator multi-way valve whose software is based on Labview. According to the relevant requirements of multi-way valve testing standards and the characteristics of excavator multi-way valves,the designs on the hydraulic principle of the test system,data acquisition and control system are completed. The system adopts electro-hydraulic proportional technology to implement the controls of the hydraulic system,including the system pressure,flow rate,the actions of multi-way valve and loading simulation; and the software design of the test system is completed by using Labview to realize automatic data acquisition,processing,display and print functions. The system has a high degree of automation,which can effectively improve the testing efficiency of excavator multi-way valve. To conduct relevant experiments of excavator multi-way valve based on the testing system developed,and the experiment results show that the integrated testing system designed is functional and easy operation.
This paper mainly introduces an integrated electro-hydraulic testing system for excavator multi-way valve whose software is based on Labview. According to the relevant requirements of multi-way valve testing standards and the characteristics of excavator multi-way valves,the designs on the hydraulic principle of the test system,data acquisition and control system are completed. The system adopts electro-hydraulic proportional technology to implement the controls of the hydraulic system,including the system pressure,flow rate,the actions of multi-way valve and loading simulation; and the software design of the test system is completed by using Labview to realize automatic data acquisition,processing,display and print functions. The system has a high degree of automation,which can effectively improve the testing efficiency of excavator multi-way valve. To conduct relevant experiments of excavator multi-way valve based on the testing system developed,and the experiment results show that the integrated testing system designed is functional and easy operation.
Development of The Clamping and Locating Tool with Magnetic Force for Portable Detector of Car Wheel
2014, 33(9): 1373-1376.
doi: 10.13433/j.cnki.1003-8728.2014.0919
Abstract:
The existing portable automobile rim detector has shortcomings of long cycle detection,time-consuming,great effort,low efficiency,the clamping force is affected by human factors to clamp and locate. Aiming at the above-mentioned deficiencies,the structural design of clamping and locating a utomobile rim with a mean of magnetic force for the portable detector is conducted. It clamps the automobile rim with magnetic force,on the one hand,the automobile rim bear uniformly and has almost no deformation,on the other hand,man-made interference have no effect on the clamping force,and has a little impact on the measurements and accuracy. Finally,theoretical research and calculations are put forward for the clamping force required by the design,and verify the feasibility of the design.
The existing portable automobile rim detector has shortcomings of long cycle detection,time-consuming,great effort,low efficiency,the clamping force is affected by human factors to clamp and locate. Aiming at the above-mentioned deficiencies,the structural design of clamping and locating a utomobile rim with a mean of magnetic force for the portable detector is conducted. It clamps the automobile rim with magnetic force,on the one hand,the automobile rim bear uniformly and has almost no deformation,on the other hand,man-made interference have no effect on the clamping force,and has a little impact on the measurements and accuracy. Finally,theoretical research and calculations are put forward for the clamping force required by the design,and verify the feasibility of the design.
2014, 33(9): 1377-1381.
doi: 10.13433/j.cnki.1003-8728.2014.0920
Abstract:
For the need to release trapped oil pressure in the higher speed external gear pumps with involutes gear pairs,a new involutes profile was proposed for the design of relief groove,the profile was consistent with the tooth profile of involute gear,and it could achieve maximum relief area. Based on the two different relief groove types of involutes shape and rectangle shape; and the small backlash value as an example,form the trapped oil model established and validated in the early literature,the two technical indicators of both the maximum peak of trapped oil pressure and the utilization efficiency of trapped oil volume were derived and simulated,finally,all of the simulation results were compared and analyzed with each other. The results indicated that the relief area value with the relief groove of involute shape under the example parameters was from 1. 19 to 31. 59 times as large as the relief area value with the relief groove of rectangle shape; which could greatly reduce the peak of trapped oil pressure,so the phenomenon of trapped oil was alleviated,meanwhile,the utilization efficiency of trapped oil volume and the volumetric efficiency of the pump were improved, the relief effect was good. The important conclusion is summarized that the relief groove with involutes shape is able to meet the relief needs of trapped oil in the higher speed external gear pumps.
For the need to release trapped oil pressure in the higher speed external gear pumps with involutes gear pairs,a new involutes profile was proposed for the design of relief groove,the profile was consistent with the tooth profile of involute gear,and it could achieve maximum relief area. Based on the two different relief groove types of involutes shape and rectangle shape; and the small backlash value as an example,form the trapped oil model established and validated in the early literature,the two technical indicators of both the maximum peak of trapped oil pressure and the utilization efficiency of trapped oil volume were derived and simulated,finally,all of the simulation results were compared and analyzed with each other. The results indicated that the relief area value with the relief groove of involute shape under the example parameters was from 1. 19 to 31. 59 times as large as the relief area value with the relief groove of rectangle shape; which could greatly reduce the peak of trapped oil pressure,so the phenomenon of trapped oil was alleviated,meanwhile,the utilization efficiency of trapped oil volume and the volumetric efficiency of the pump were improved, the relief effect was good. The important conclusion is summarized that the relief groove with involutes shape is able to meet the relief needs of trapped oil in the higher speed external gear pumps.
2014, 33(9): 1382-1386.
doi: 10.13433/j.cnki.1003-8728.2014.0921
Abstract:
This paper introduced the basic principle of near-field acoustical holography(NAH) and reconstruction algorithm based on Helmholtz equation-least squares(HELS) method. The noise of a four-cylinder inline gasoline engine was measured and analyzed by using near field acoustic holography measurement system which based on HELS algorithm. Then acoustic holograms of noise radiated from engine surface under different conditions were achieved. In order to reduce the noise of the engine,the visual results of the acoustic field information such as acoustic pressure,acoustic intensity and surface velocity under the frequency of noise peak were evaluated. The location of the major internal vibratory sources of the noise and the external radiated noise characteristics at near distance were identified,which provided a more accurate evidence for further noise abatement.
This paper introduced the basic principle of near-field acoustical holography(NAH) and reconstruction algorithm based on Helmholtz equation-least squares(HELS) method. The noise of a four-cylinder inline gasoline engine was measured and analyzed by using near field acoustic holography measurement system which based on HELS algorithm. Then acoustic holograms of noise radiated from engine surface under different conditions were achieved. In order to reduce the noise of the engine,the visual results of the acoustic field information such as acoustic pressure,acoustic intensity and surface velocity under the frequency of noise peak were evaluated. The location of the major internal vibratory sources of the noise and the external radiated noise characteristics at near distance were identified,which provided a more accurate evidence for further noise abatement.
2014, 33(9): 1387-1392.
doi: 10.13433/j.cnki.1003-8728.2014.0922
Abstract:
Based on an 8 degree of freedom human-seat dynamic model and a 31 degree of freedom vehicle model,a human-vehicle-bridge coupled system was established. The vehicle and the bridge were coupled by wheel /rail contact force and displacement coordination condition. The coupled equations of the system were built and were solved by Newmark-beta method. The running process of the 300 km /h railway vehicle on the bridge was simulated and the human vibration comfortableness was evaluated with the riding comfort value. The effects of track irregularity,running speed,number and location of passengers were also discussed.
Based on an 8 degree of freedom human-seat dynamic model and a 31 degree of freedom vehicle model,a human-vehicle-bridge coupled system was established. The vehicle and the bridge were coupled by wheel /rail contact force and displacement coordination condition. The coupled equations of the system were built and were solved by Newmark-beta method. The running process of the 300 km /h railway vehicle on the bridge was simulated and the human vibration comfortableness was evaluated with the riding comfort value. The effects of track irregularity,running speed,number and location of passengers were also discussed.
2014, 33(9): 1393-1396.
doi: 10.13433/j.cnki.1003-8728.2014.0923
Abstract:
This paper presents an optimization method for vehicle crash safty based on reverse theory. To improve the accuracy of finite element simulation on the analysis of vehicle safty,an inverse problem is established to obtain the material characteristic parameters by combining finite element simulation and test verification. Then,the structure optimization of a truck cab is conducted,in which the real parameters are utilized. The parameters which have great impact on the safety of driver are selected as optimization objectives and a genetic algorithm is adopted to solve this multi-objective optimization problems. The result indicates that there is some differences between the default material parameters of the finite element simualtion software and the experimental data. The optimized results by using experimental data will be more accurate than those obtianed by using the default material parameters.
This paper presents an optimization method for vehicle crash safty based on reverse theory. To improve the accuracy of finite element simulation on the analysis of vehicle safty,an inverse problem is established to obtain the material characteristic parameters by combining finite element simulation and test verification. Then,the structure optimization of a truck cab is conducted,in which the real parameters are utilized. The parameters which have great impact on the safety of driver are selected as optimization objectives and a genetic algorithm is adopted to solve this multi-objective optimization problems. The result indicates that there is some differences between the default material parameters of the finite element simualtion software and the experimental data. The optimized results by using experimental data will be more accurate than those obtianed by using the default material parameters.
2014, 33(9): 1397-1402.
doi: 10.13433/j.cnki.1003-8728.2014.0924
Abstract:
Aerodynamic characteristics determine the design quality and performance of the Formula SAE(FSAE)car,and two key coefficients of aerodynamic characteristics are drag coefficient and negative lift coefficient. Rear wing has great influence on the aerodynamic performance of a FSAE car. Numerical methods were used to analyze and contrast the aerodynamic performance of the wing on different structural parameters such as wing profile,angle of attack and ground clearance. According to the varying laws of drag coefficient and negative lift coefficient as well as matching principle,the best design scheme of the wing was determined. The results show that a wing with large curvature and thick body can provide more lift,the best angle of attack is 45�and the optimum value for ground clearance is 88 mm.
Aerodynamic characteristics determine the design quality and performance of the Formula SAE(FSAE)car,and two key coefficients of aerodynamic characteristics are drag coefficient and negative lift coefficient. Rear wing has great influence on the aerodynamic performance of a FSAE car. Numerical methods were used to analyze and contrast the aerodynamic performance of the wing on different structural parameters such as wing profile,angle of attack and ground clearance. According to the varying laws of drag coefficient and negative lift coefficient as well as matching principle,the best design scheme of the wing was determined. The results show that a wing with large curvature and thick body can provide more lift,the best angle of attack is 45�and the optimum value for ground clearance is 88 mm.
2014, 33(9): 1403-1407.
doi: 10.13433/j.cnki.1003-8728.2014.0925
Abstract:
Dynamic response of container flat car was analyzed using the flexible multibody dynamics method. The rigid-flexible coupling dynamic model considering the flexibility of carbody was established and the simulation results were compared with that of the rigid model. The results show that the RMS of carbody acceleration of the rigid-flexible coupling model is greater than that of the rigid model and the maximum difference is 2. 8 m /s2. The spectrum analysis of the acceleration of carbody shows that the first-order torsion mode,first-order vertical bending mode,and first-order transverse bending mode significantly affect the vibration of carbody in empty load case. It also indicates that the mode of carbody changes after loading containers. After loading containers,the mode of carbody is mainly torsion and local vibration which affect the vertical vibration of carbody end significantly.
Dynamic response of container flat car was analyzed using the flexible multibody dynamics method. The rigid-flexible coupling dynamic model considering the flexibility of carbody was established and the simulation results were compared with that of the rigid model. The results show that the RMS of carbody acceleration of the rigid-flexible coupling model is greater than that of the rigid model and the maximum difference is 2. 8 m /s2. The spectrum analysis of the acceleration of carbody shows that the first-order torsion mode,first-order vertical bending mode,and first-order transverse bending mode significantly affect the vibration of carbody in empty load case. It also indicates that the mode of carbody changes after loading containers. After loading containers,the mode of carbody is mainly torsion and local vibration which affect the vertical vibration of carbody end significantly.
2014, 33(9): 1408-1412.
doi: 10.13433/j.cnki.1003-8728.2014.0926
Abstract:
Aiming at the low connecting reliability resulting from uncontrolling the friction coefficient of bolted joints in vehicle assembly,by carrying out tightening experiments on different zinc-coated high strength bolted joints,and lateral experiments of bolted joints in different friction coefficients,effect of the friction coefficient on the performance of bolt connection are analyzed on different aspects of controlling torque coefficients' stability,energy dissipation of torque and preventing loosening. The results show that the decrease in dispersion of friction coefficient will reduce the dispersion of torque coefficient,and the increase in friction coefficient will better the performance of preventing loosening but lessen the conversion rate of toque,and to control the bolts' friction coefficients can control torque coefficients' stability and improve stability of preventing loosening. And the controlling range of fiction coefficients is also recommended.
Aiming at the low connecting reliability resulting from uncontrolling the friction coefficient of bolted joints in vehicle assembly,by carrying out tightening experiments on different zinc-coated high strength bolted joints,and lateral experiments of bolted joints in different friction coefficients,effect of the friction coefficient on the performance of bolt connection are analyzed on different aspects of controlling torque coefficients' stability,energy dissipation of torque and preventing loosening. The results show that the decrease in dispersion of friction coefficient will reduce the dispersion of torque coefficient,and the increase in friction coefficient will better the performance of preventing loosening but lessen the conversion rate of toque,and to control the bolts' friction coefficients can control torque coefficients' stability and improve stability of preventing loosening. And the controlling range of fiction coefficients is also recommended.
2014, 33(9): 1413-1418.
doi: 10.13433/j.cnki.1003-8728.2014.0927
Abstract:
Considering that car body side crash safety and lightweight are mutual restraint issues,a SUV side crash simulation model was established to study this problem. The key components which have significant influence on the vehicle body safety was determined through analysis of the simulation results. Then their thicknesses were taken as design variables. With the experimental data obtained by uniform experimental design,the stepwise regression method was used to construct response surface approximation model considering two factors,namely vehicle side crash safety and lightweight. Then applying the sequential quadratic programming(SQP) method combined with adaptive weighted multi-objective optimization method,the multidisciplinary collaborative optimization of the vehicle body structure was carried out,thus the results show that the side body crash safety was significantly improved while the vehicle lightweight design was ensured.
Considering that car body side crash safety and lightweight are mutual restraint issues,a SUV side crash simulation model was established to study this problem. The key components which have significant influence on the vehicle body safety was determined through analysis of the simulation results. Then their thicknesses were taken as design variables. With the experimental data obtained by uniform experimental design,the stepwise regression method was used to construct response surface approximation model considering two factors,namely vehicle side crash safety and lightweight. Then applying the sequential quadratic programming(SQP) method combined with adaptive weighted multi-objective optimization method,the multidisciplinary collaborative optimization of the vehicle body structure was carried out,thus the results show that the side body crash safety was significantly improved while the vehicle lightweight design was ensured.
2014, 33(9): 1419-1422.
doi: 10.13433/j.cnki.1003-8728.2014.0928
Abstract:
Take one disc brake of a certain type of vehicle as study objection. Establishing the 3D model on Pro /Engineer software and finite element model on OptiStruct,furthermore,analyze the normal modes of disc brake. In order to avoid the noise carried out by the resonance between brake disc and the brake body,adopt the theory of variable density and establish an optimization that sets the minimum mass as objective,element density as variable,and the third modes of brake body as constraint. The analysis result provides an optimization that reduces the third normal modes,and involves the best distribution of material,with which the resonance can be avoided and the noise reduced largely.
Take one disc brake of a certain type of vehicle as study objection. Establishing the 3D model on Pro /Engineer software and finite element model on OptiStruct,furthermore,analyze the normal modes of disc brake. In order to avoid the noise carried out by the resonance between brake disc and the brake body,adopt the theory of variable density and establish an optimization that sets the minimum mass as objective,element density as variable,and the third modes of brake body as constraint. The analysis result provides an optimization that reduces the third normal modes,and involves the best distribution of material,with which the resonance can be avoided and the noise reduced largely.
2014, 33(9): 1423-1427.
doi: 10.13433/j.cnki.1003-8728.2014.0929
Abstract:
By using the numerical simulation method,the paper study two major effect factors-water spray location and quantity-on the combustion process of water ramjet. The physical,mathematical,turbulent,combustion models are metal /water ramjet,N-S equations,realizable k-ε and Eddy-dissipation,respectively. Through simulating the afterburning chamber under different conditions and using combustion rate as evaluation criteria,the paper gets an optimization secondary water spray location and distribution ratio of the first water inlet,which provides theoretical references for water ramjet design.
By using the numerical simulation method,the paper study two major effect factors-water spray location and quantity-on the combustion process of water ramjet. The physical,mathematical,turbulent,combustion models are metal /water ramjet,N-S equations,realizable k-ε and Eddy-dissipation,respectively. Through simulating the afterburning chamber under different conditions and using combustion rate as evaluation criteria,the paper gets an optimization secondary water spray location and distribution ratio of the first water inlet,which provides theoretical references for water ramjet design.
2014, 33(9): 1428-1433.
doi: 10.13433/j.cnki.1003-8728.2014.0930
Abstract:
Aim at the reliability enhancement problem of complex mechanics-electronics-hydraulics integration products-aircraft Electric Hydrostatic Actuator(EHA),the method to calculate EHA reliability based on GO methodology is studied,and a new GO analysis and design method for EHA reliability is proposed. The GO plot and GO operation of EHA with multi-component redundancy parameters are presented. The reliability calculation formula of EHA with multi-component redundancy is derived. The design theory of EHA with high reliability is obtained. A new approach to apply GO method to EHA redundancy design is provided. The design example shows that the EHA reliability analysis and design method based on GO methodology has the advantage of high computation accuracy,and it can obtain the optimal redundancy design parameters rapidly. This method is viable in systematic analysis and design for EHA reliability.
Aim at the reliability enhancement problem of complex mechanics-electronics-hydraulics integration products-aircraft Electric Hydrostatic Actuator(EHA),the method to calculate EHA reliability based on GO methodology is studied,and a new GO analysis and design method for EHA reliability is proposed. The GO plot and GO operation of EHA with multi-component redundancy parameters are presented. The reliability calculation formula of EHA with multi-component redundancy is derived. The design theory of EHA with high reliability is obtained. A new approach to apply GO method to EHA redundancy design is provided. The design example shows that the EHA reliability analysis and design method based on GO methodology has the advantage of high computation accuracy,and it can obtain the optimal redundancy design parameters rapidly. This method is viable in systematic analysis and design for EHA reliability.
2014, 33(9): 1439-1444.
doi: 10.13433/j.cnki.1003-8728.2014.0932
Abstract:
An approach was proposed for the dimensional synthesis of a 3-DOF driving platform of flight simulator.The driving platform was composed of a moving platform,a static platform,three UPS unconstrained active branch chains and a UP driven branch chain. The main load was born by the driven branch chain which was composed of pneumatic support unit through the compressed gas in order to improve the simulation performance of driving platform. The simulation performance was presented to be taken as an evaluating index which was based on the vector 2-norm with the aid of the characters of Rayleigh quotient and vector. The influence law of scale parameters on the stiffness,operating performance and simulation performance of the driving platform was discussed through monotonic analysis and it was adopted to seek the optimal solution of the evaluation function. The effectiveness of the method was proved by the example.
An approach was proposed for the dimensional synthesis of a 3-DOF driving platform of flight simulator.The driving platform was composed of a moving platform,a static platform,three UPS unconstrained active branch chains and a UP driven branch chain. The main load was born by the driven branch chain which was composed of pneumatic support unit through the compressed gas in order to improve the simulation performance of driving platform. The simulation performance was presented to be taken as an evaluating index which was based on the vector 2-norm with the aid of the characters of Rayleigh quotient and vector. The influence law of scale parameters on the stiffness,operating performance and simulation performance of the driving platform was discussed through monotonic analysis and it was adopted to seek the optimal solution of the evaluation function. The effectiveness of the method was proved by the example.
