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RSS2016 Vol. 35, No. 12
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2016, 35(12): 1805-1810.
doi: 10.13433/j.cnki.1003-8728.2016.1201
PDF 1036KB
Abstract:
The acquisition and analysis of casing's acceleration vibration signal is a significant method to realize aero-engine's fault diagnosis. Neural networks can classify vibration faults with their strong nonlinear mapping ability. 5 different types of fan casing vibration faults are simulated on the rotor-bearing-casing coupled vibration experiment system. Accurate judgment of faults can't gain from the preliminary analysis of signal's frequency spectrum. Single fault is classified from faults by probabilistic neural networks (PNN) using vibration data's frequency and amplitude domain parameters. Methods with different parameters are compared and the feasibility of PNN using in casing vibration fault diagnosis is tested.
The acquisition and analysis of casing's acceleration vibration signal is a significant method to realize aero-engine's fault diagnosis. Neural networks can classify vibration faults with their strong nonlinear mapping ability. 5 different types of fan casing vibration faults are simulated on the rotor-bearing-casing coupled vibration experiment system. Accurate judgment of faults can't gain from the preliminary analysis of signal's frequency spectrum. Single fault is classified from faults by probabilistic neural networks (PNN) using vibration data's frequency and amplitude domain parameters. Methods with different parameters are compared and the feasibility of PNN using in casing vibration fault diagnosis is tested.
Influence of Shape Error and Position Error of a Motor on Fatigue Life of a Deep Groove Ball Bearing
2016, 35(12): 1811-1816.
doi: 10.13433/j.cnki.1003-8728.2016.1202
Abstract:
In order to study the influence of processing error and assembling error on the fatigue life of a deep groove ball bearing, a calculation model of bearing ring tilting caused by the shape error and position error of a motor is established. The contact angle, contact load, contact stress, spin to roll ratio and bearing temperature distribution caused by different tilt angles between inner ring and outer ring is quantitatively calculated. At the position of the highest contact angle, the values of bearing temperature, contact stress and spin to roll ratio are larger than those at other positions. The influence of different inclination angles between the rings on the fatigue life of the deep groove bearing is obtained. The calculation results show that the tilt angle between the rings is within 3 degrees and is caused by the motor's error when the radial clearance is zero and that the fatigue life of the deep groove ball bearing is reduced by less than 10%.
In order to study the influence of processing error and assembling error on the fatigue life of a deep groove ball bearing, a calculation model of bearing ring tilting caused by the shape error and position error of a motor is established. The contact angle, contact load, contact stress, spin to roll ratio and bearing temperature distribution caused by different tilt angles between inner ring and outer ring is quantitatively calculated. At the position of the highest contact angle, the values of bearing temperature, contact stress and spin to roll ratio are larger than those at other positions. The influence of different inclination angles between the rings on the fatigue life of the deep groove bearing is obtained. The calculation results show that the tilt angle between the rings is within 3 degrees and is caused by the motor's error when the radial clearance is zero and that the fatigue life of the deep groove ball bearing is reduced by less than 10%.
2016, 35(12): 1817-1823.
doi: 10.13433/j.cnki.1003-8728.2016.1203
Abstract:
The static analysis of 3PUS-S(P) metamorphic parallel mechanism is received when the result of force mapping model between joint space and operational space is already gained. The 3PUS-S(P) metamorphic parallel mechanism consists of a moving platform, a static platform, three PUS unconstraint branched chains and an S(P) constraint branched chain. This mechanism has two configurations:in the first configuration, the moving platform is in possession of three revolute degrees of freedom; in the second configuration, the moving platform has an extra translational freedom in the direction of radius which is perpendicular to the moving platform. Based on the screw theory, the complete Jacobian matrix is established firstly. Secondly, the force mapping model between the input and the output is obtained according to the principle of virtual work. Then, the performance index of the force transmission is found. At last, the mapping relationship between the performance index of the force transmission and the geometric parameters of the mechanism is analyzed. The study paves the way for the further application of 3PUS-S(P) metamorphic parallel mechanism.
The static analysis of 3PUS-S(P) metamorphic parallel mechanism is received when the result of force mapping model between joint space and operational space is already gained. The 3PUS-S(P) metamorphic parallel mechanism consists of a moving platform, a static platform, three PUS unconstraint branched chains and an S(P) constraint branched chain. This mechanism has two configurations:in the first configuration, the moving platform is in possession of three revolute degrees of freedom; in the second configuration, the moving platform has an extra translational freedom in the direction of radius which is perpendicular to the moving platform. Based on the screw theory, the complete Jacobian matrix is established firstly. Secondly, the force mapping model between the input and the output is obtained according to the principle of virtual work. Then, the performance index of the force transmission is found. At last, the mapping relationship between the performance index of the force transmission and the geometric parameters of the mechanism is analyzed. The study paves the way for the further application of 3PUS-S(P) metamorphic parallel mechanism.
2016, 35(12): 1824-1828.
doi: 10.13433/j.cnki.1003-8728.2016.1204
Abstract:
Since the composite error of the motion of path generating mechanisms is multi-dimensional and strongly nonlinear, it is difficult to obtain the highly accurate mean and variance of the composite error with the Taylor series expansion. Therefore, this paper uses the dimensional reduction method to build the probabilistic model of the motion error. As an example, it presents a four-bar planar path linkage with random number of dimensions and establishes a model of the composite motion error based on kinematic analysis. With the bivariate dimension reduction method, the motion error is approximated by the sum of univariate and bivariate functions of dimensional variables. The Gauss-Hermite Quadrature rule is applied to evaluate the statistical moments of the motion error, and then its mean and standard deviation functions are derived. This application achieves an optimal balance between accuracy and efficiency. Finally, a numerical example is given to demonstrate the effectiveness of the bivariate dimensional reduction method.
Since the composite error of the motion of path generating mechanisms is multi-dimensional and strongly nonlinear, it is difficult to obtain the highly accurate mean and variance of the composite error with the Taylor series expansion. Therefore, this paper uses the dimensional reduction method to build the probabilistic model of the motion error. As an example, it presents a four-bar planar path linkage with random number of dimensions and establishes a model of the composite motion error based on kinematic analysis. With the bivariate dimension reduction method, the motion error is approximated by the sum of univariate and bivariate functions of dimensional variables. The Gauss-Hermite Quadrature rule is applied to evaluate the statistical moments of the motion error, and then its mean and standard deviation functions are derived. This application achieves an optimal balance between accuracy and efficiency. Finally, a numerical example is given to demonstrate the effectiveness of the bivariate dimensional reduction method.
2016, 35(12): 1829-1833.
doi: 10.13433/j.cnki.1003-8728.2016.1205
Abstract:
The paper studies the friction pair of water hydraulic slide valve core. In order to improve its hydrodynamic bearing capacity and lubrication characteristics, micro-textures are set up on its surface. The computational fluid dynamics method based on the Navier-Stokes equation is used to analyze the flow field of the micro-texture valve core friction pair. The core surface pressure distribution curves, pressure bearing and friction curves are obtained. The influence of valve core overlap length on the hydrodynamic bearing capacity and lubrication characteristics of the friction pair is analyzed under the condition that the overlap length is greater than 2.5 mm. The analysis results show that the smooth valve core does not produce hydrodynamic lubrication effect but that the micro-texture valve core surface produces oil film's dynamic pressure support. With the decrease of the core overlap length, the bearing capacity on the micro-texture core surface increases; thus the contact friction between the valve core and the sleeve decreases.
The paper studies the friction pair of water hydraulic slide valve core. In order to improve its hydrodynamic bearing capacity and lubrication characteristics, micro-textures are set up on its surface. The computational fluid dynamics method based on the Navier-Stokes equation is used to analyze the flow field of the micro-texture valve core friction pair. The core surface pressure distribution curves, pressure bearing and friction curves are obtained. The influence of valve core overlap length on the hydrodynamic bearing capacity and lubrication characteristics of the friction pair is analyzed under the condition that the overlap length is greater than 2.5 mm. The analysis results show that the smooth valve core does not produce hydrodynamic lubrication effect but that the micro-texture valve core surface produces oil film's dynamic pressure support. With the decrease of the core overlap length, the bearing capacity on the micro-texture core surface increases; thus the contact friction between the valve core and the sleeve decreases.
2016, 35(12): 1834-1841.
doi: 10.13433/j.cnki.1003-8728.2016.1206
Abstract:
To reduce the power matching loss of rotary drilling rig caused by the fluctuation of load during the construction process, a comprehensive power matching control strategy is proposed. Taking 220 kN·m rotary drilling rig as the research object and using the AMESim simulation software, the models for the traditional constant-power control system and the comprehensive power matching control system are set up and the comparisons of economic index and performance index under the different load are made. The results indicate that the comprehensive power matching control system can reduce the fuel consumption by 6% comparing with traditional constant-power control system, which improves the energy efficiency and prolongs the service life of equipment.
To reduce the power matching loss of rotary drilling rig caused by the fluctuation of load during the construction process, a comprehensive power matching control strategy is proposed. Taking 220 kN·m rotary drilling rig as the research object and using the AMESim simulation software, the models for the traditional constant-power control system and the comprehensive power matching control system are set up and the comparisons of economic index and performance index under the different load are made. The results indicate that the comprehensive power matching control system can reduce the fuel consumption by 6% comparing with traditional constant-power control system, which improves the energy efficiency and prolongs the service life of equipment.
2016, 35(12): 1842-1847.
doi: 10.13433/j.cnki.1003-8728.2016.1207
Abstract:
The old time domain features from the cutting force are vulnerable to changes of cutting parameters. So it is not suitable for tool wear monitoring under variable parameters. In order to solve the above mentioned problem, a new set of dimensionless time domain feature including normalized cutting force indicator NCF, variation coefficient Cv and peak force ratio MFR are adopted. To verify the effectiveness of the present feature for tool wear monitoring under variable parameters, the end milling experiment of TC4 titanium alloy was designed. Then, the present features and the old features are input Support Vector Machines (SVM) to monitor the tool wear state respectively. The analysis and comparison results show that the dimensionless time domain feature presented in the paper is not sensitive to the cutting parameters, but only sensitive to the tool wear state. Hence, the tool wear state monitoring under variable parameters can be implemented.
The old time domain features from the cutting force are vulnerable to changes of cutting parameters. So it is not suitable for tool wear monitoring under variable parameters. In order to solve the above mentioned problem, a new set of dimensionless time domain feature including normalized cutting force indicator NCF, variation coefficient Cv and peak force ratio MFR are adopted. To verify the effectiveness of the present feature for tool wear monitoring under variable parameters, the end milling experiment of TC4 titanium alloy was designed. Then, the present features and the old features are input Support Vector Machines (SVM) to monitor the tool wear state respectively. The analysis and comparison results show that the dimensionless time domain feature presented in the paper is not sensitive to the cutting parameters, but only sensitive to the tool wear state. Hence, the tool wear state monitoring under variable parameters can be implemented.
2016, 35(12): 1848-1856.
doi: 10.13433/j.cnki.1003-8728.2016.1208
Abstract:
Aiming at the autoclave forming quality problem caused by heating rate fluctuation, this paper puts forward the robust design method of stress relaxation process based on the tolerance model and robust ε-support vector machines, and gives an improved method to calculate the tolerance. The optimization mathematical model for process parameters is established at first and the derivative of plastic strain and the upgrade rate of material performance are chosen as the optimization goal and optimization constraint respectively. The response surfaces of optimization target, optimization constraint and optimization constraint tolerance are established and the tolerance of optimization constraint is introduced into the optimization model; the robust process feasible domain can be calculated after updating optimization constraints and finally the optimal process parameters can be obtained in feasible domain. The original process parameters and the optimized ones are used respectively to carry out stress relaxation experiments. With the optimized parameters, all parts satisfy the constraints. By contrasting, 30% of parts do not meet the requirements with the original parameters, proving the proposed method is effective and reliable.
Aiming at the autoclave forming quality problem caused by heating rate fluctuation, this paper puts forward the robust design method of stress relaxation process based on the tolerance model and robust ε-support vector machines, and gives an improved method to calculate the tolerance. The optimization mathematical model for process parameters is established at first and the derivative of plastic strain and the upgrade rate of material performance are chosen as the optimization goal and optimization constraint respectively. The response surfaces of optimization target, optimization constraint and optimization constraint tolerance are established and the tolerance of optimization constraint is introduced into the optimization model; the robust process feasible domain can be calculated after updating optimization constraints and finally the optimal process parameters can be obtained in feasible domain. The original process parameters and the optimized ones are used respectively to carry out stress relaxation experiments. With the optimized parameters, all parts satisfy the constraints. By contrasting, 30% of parts do not meet the requirements with the original parameters, proving the proposed method is effective and reliable.
2016, 35(12): 1857-1864.
doi: 10.13433/j.cnki.1003-8728.2016.1209
Abstract:
Focusing on the stability of disassembly process and the limitation of graph-based disassembly model for complex products, a new disassembly sequence planning(DSP) method based on disassembly stability is presented. The characteristics and principles of disassembly for green manufacturing and circular economy are analyzed. A new disassembly information analysis model based on set and matrix is constructed under the analysis of the product CAD model, which includes component types, the feasible disassembly direction sets of components, the component dismantling space restriction matrix, the component contact matrix and the component degree of freedom(DOF) constraint matrix. The priority and stability principles are also presented. Furthermore, the algorithm of this new DSP method is proposed. The feasibility and practicability of the presented method is verified by a case of both complete disassembly and selected disassembly.
Focusing on the stability of disassembly process and the limitation of graph-based disassembly model for complex products, a new disassembly sequence planning(DSP) method based on disassembly stability is presented. The characteristics and principles of disassembly for green manufacturing and circular economy are analyzed. A new disassembly information analysis model based on set and matrix is constructed under the analysis of the product CAD model, which includes component types, the feasible disassembly direction sets of components, the component dismantling space restriction matrix, the component contact matrix and the component degree of freedom(DOF) constraint matrix. The priority and stability principles are also presented. Furthermore, the algorithm of this new DSP method is proposed. The feasibility and practicability of the presented method is verified by a case of both complete disassembly and selected disassembly.
2016, 35(12): 1865-1870.
doi: 10.13433/j.cnki.1003-8728.2016.1210
Abstract:
The ball supply unit is designed for the BGA/CSP (ball grid array, chip size package)ball mounter,it uses pre-buried method for ball supply and it can solve the problem of solder ball missing or conglutination, the ball size is from 0.15 mm to 0.76 mm. The ball supply unit requires high horizontal positioning precision. The mathematical model of alignment accuracy between the ball supply unit and the ball mount head is analyzed, and the error analysis shows that the backlash of the ball supply unit has a great influence on the commissioning of ball mount head. Because of the backlash error of the transmission chain, a mechanism is designed to eliminate the backlash. By calculating the stresses and torque, two suitable cylinders are selected. Finally, the experiments of commissioning indicate that the ball supply unit can realize the precision requirement of the ball mounter.
The ball supply unit is designed for the BGA/CSP (ball grid array, chip size package)ball mounter,it uses pre-buried method for ball supply and it can solve the problem of solder ball missing or conglutination, the ball size is from 0.15 mm to 0.76 mm. The ball supply unit requires high horizontal positioning precision. The mathematical model of alignment accuracy between the ball supply unit and the ball mount head is analyzed, and the error analysis shows that the backlash of the ball supply unit has a great influence on the commissioning of ball mount head. Because of the backlash error of the transmission chain, a mechanism is designed to eliminate the backlash. By calculating the stresses and torque, two suitable cylinders are selected. Finally, the experiments of commissioning indicate that the ball supply unit can realize the precision requirement of the ball mounter.
2016, 35(12): 1871-1876.
doi: 10.13433/j.cnki.1003-8728.2016.1211
Abstract:
The deformation states of cone and pyramid parts in different areas has been done, and it studied the effects of the tool diameter on the deformation states and the strain distribution in the different corner radius of the pyramid parts, all of these are carried out by theoretical calculation, finite element simulation and experiment. The results show that the cone parts have plane strain, tension-tension zone and tension-compression zone respectively; four corners of pyramid parts are under tension-tension zone which occur double-tension; the sheet has a more obvious tendency of double-tension with the increasing diameter; the bigger corner radius of the pyramid parts lead to more similar deformation state of plane strain state around the corner.
The deformation states of cone and pyramid parts in different areas has been done, and it studied the effects of the tool diameter on the deformation states and the strain distribution in the different corner radius of the pyramid parts, all of these are carried out by theoretical calculation, finite element simulation and experiment. The results show that the cone parts have plane strain, tension-tension zone and tension-compression zone respectively; four corners of pyramid parts are under tension-tension zone which occur double-tension; the sheet has a more obvious tendency of double-tension with the increasing diameter; the bigger corner radius of the pyramid parts lead to more similar deformation state of plane strain state around the corner.
2016, 35(12): 1877-1881.
doi: 10.13433/j.cnki.1003-8728.2016.1212
Abstract:
In order to judge and predict the tool wear in laser assisted machining cemented carbide, the contrast experiments of tool flank wear in conventional machining and laser assisted maching were conducted in order to study the tool wear mechanism. Based on the grey-Markov theory, the grey prediction model and grey-Markov prediction model for tool flank wear in laser assisted machining cemented carbide were established after analyzing the data collected through experiments, and the tool wear values were predicted based on those two models. The results showed that the predicted values are very close to the measured values, especially the fitting precision of data obtained with the grey-Markov prediction model is better and its predicted results is more reliable, which can better meet the requirements of practical engineering.
In order to judge and predict the tool wear in laser assisted machining cemented carbide, the contrast experiments of tool flank wear in conventional machining and laser assisted maching were conducted in order to study the tool wear mechanism. Based on the grey-Markov theory, the grey prediction model and grey-Markov prediction model for tool flank wear in laser assisted machining cemented carbide were established after analyzing the data collected through experiments, and the tool wear values were predicted based on those two models. The results showed that the predicted values are very close to the measured values, especially the fitting precision of data obtained with the grey-Markov prediction model is better and its predicted results is more reliable, which can better meet the requirements of practical engineering.
2016, 35(12): 1882-1887.
doi: 10.13433/j.cnki.1003-8728.2016.1213
Abstract:
Aiming at the condition-based maintenance of equipments, a novel assessment method of rolling bearing performance degradation combining wavelet packet singular spectral entropy (WPSSE) and support vector data description (SVDD) was proposed. Firstly, WPSSEs were extracted from bearing full-life-cycle vibration signals as feature vectors to describe a bearing running state. Secondly, SVDD was trained using the feature vectors under normal condition to get the fiducial hypersphere of normal state. Then, the relative distance between full-life-cycle feature vectors of bearing and fiducial hypersphere was calculated as a quantitative index of performance degradation, and the failure threshold and incipient fault threshold were set. Analytical results of experimental data indicated that compared with the degradation evaluation method based on wavelet packet and SVDD, the proposed method had stronger ability for incipient fault detection, and it could describe the stages of bearing performance degradation more accurately. Finally, Hilbert envelope demodulation method based on empirical mode demodulation was used to validate the reliability of evaluation result.
Aiming at the condition-based maintenance of equipments, a novel assessment method of rolling bearing performance degradation combining wavelet packet singular spectral entropy (WPSSE) and support vector data description (SVDD) was proposed. Firstly, WPSSEs were extracted from bearing full-life-cycle vibration signals as feature vectors to describe a bearing running state. Secondly, SVDD was trained using the feature vectors under normal condition to get the fiducial hypersphere of normal state. Then, the relative distance between full-life-cycle feature vectors of bearing and fiducial hypersphere was calculated as a quantitative index of performance degradation, and the failure threshold and incipient fault threshold were set. Analytical results of experimental data indicated that compared with the degradation evaluation method based on wavelet packet and SVDD, the proposed method had stronger ability for incipient fault detection, and it could describe the stages of bearing performance degradation more accurately. Finally, Hilbert envelope demodulation method based on empirical mode demodulation was used to validate the reliability of evaluation result.
2016, 35(12): 1888-1893.
doi: 10.13433/j.cnki.1003-8728.2016.1214
Abstract:
A novel cable driving serial bending unit was introduced, and structural optimization and workspace simulation were carried out. With theoretical analysis and numerical simulation, the bending unit was optimized to prevent cable slacking during bending operation, and control accuracy was enhanced. Forward kinematic model of multi-degrees of freedom instrument was established and the final position was calculated by Denavit-Hartenberg (D-H) method. Based on Monte Carlo methods, workspace of multi-degrees of freedom instrument and traditional straight instrument was obtained and compared, and then the Unigraphics (UG) software was employed to calculate the exact workspace volume. The results indicated that multi-degrees of freedom instrument had more workspace and dexterity than straight instrument.
A novel cable driving serial bending unit was introduced, and structural optimization and workspace simulation were carried out. With theoretical analysis and numerical simulation, the bending unit was optimized to prevent cable slacking during bending operation, and control accuracy was enhanced. Forward kinematic model of multi-degrees of freedom instrument was established and the final position was calculated by Denavit-Hartenberg (D-H) method. Based on Monte Carlo methods, workspace of multi-degrees of freedom instrument and traditional straight instrument was obtained and compared, and then the Unigraphics (UG) software was employed to calculate the exact workspace volume. The results indicated that multi-degrees of freedom instrument had more workspace and dexterity than straight instrument.
2016, 35(12): 1894-1899.
doi: 10.13433/j.cnki.1003-8728.2016.1215
Abstract:
Particle image velocimetry(PIV) was conducted in order to get the dynamic characteristics of the two dimensional fluid fields in a small-scale feedback fluidic oscillator operated under low Reynolds number flow. Velocity distributions of the whole internal fluid flow under steady state were gained when the flow rate ranged from 100 to 300 ml/min. The jet flow was analyzed by monitoring the Y components of velocities in the outlets of two feedback channels in the experiments. Oscillation frequencies under different flow rate were obtained by two data analysis methods, fast Fourier transforms and wavelet transforms. Characteristics of oscillation frequency and Strouhal number were also obtained. The results verified that the internal fluid flow of the small-scale feedback fluidic oscillator presented periodic oscillation, the oscillation frequencies obtained by fast Fourier transforms and wavelet transforms were nearly approximate, the characteristics of oscillation frequency and Strouhal number were nonlinear.
Particle image velocimetry(PIV) was conducted in order to get the dynamic characteristics of the two dimensional fluid fields in a small-scale feedback fluidic oscillator operated under low Reynolds number flow. Velocity distributions of the whole internal fluid flow under steady state were gained when the flow rate ranged from 100 to 300 ml/min. The jet flow was analyzed by monitoring the Y components of velocities in the outlets of two feedback channels in the experiments. Oscillation frequencies under different flow rate were obtained by two data analysis methods, fast Fourier transforms and wavelet transforms. Characteristics of oscillation frequency and Strouhal number were also obtained. The results verified that the internal fluid flow of the small-scale feedback fluidic oscillator presented periodic oscillation, the oscillation frequencies obtained by fast Fourier transforms and wavelet transforms were nearly approximate, the characteristics of oscillation frequency and Strouhal number were nonlinear.
2016, 35(12): 1900-1905.
doi: 10.13433/j.cnki.1003-8728.2016.1216
Abstract:
A manifold learning method of t-distributed stochastic neighbor embedding(t-SNE) is used in fault feature extraction of mechanical vibration signal to realize the dimension reduction of high-dimensional feature information. The acquired vibration signal is decomposed into wavelet subspaces by wavelet packet decomposition algorithm, and high dimensional feature vector is construct by the calculation of wavelet threshold entropy of every subspace, and then the stochastic neighbor embedding method based on t distribution is applied to reduce the constructed high-dimensional feature vector to low dimensional vector to acquire the features of fault. Fault simulation experiment on Bently rotor kit has been implemented, and two groups of high dimensional data vectors were been constructed by statistical parameter and wavelet package threshold entropy with the acquired vibration signals, and two groups of high dimensional vectors were reduced to 2 dimension vector by t-SNE method. By comparing, we validate that the extraction method of t-SNE dimension reduction of data based on high dimensional data constructed by Wavelet Packet Threshold Entropy is effective in distinguishing the fault features.
A manifold learning method of t-distributed stochastic neighbor embedding(t-SNE) is used in fault feature extraction of mechanical vibration signal to realize the dimension reduction of high-dimensional feature information. The acquired vibration signal is decomposed into wavelet subspaces by wavelet packet decomposition algorithm, and high dimensional feature vector is construct by the calculation of wavelet threshold entropy of every subspace, and then the stochastic neighbor embedding method based on t distribution is applied to reduce the constructed high-dimensional feature vector to low dimensional vector to acquire the features of fault. Fault simulation experiment on Bently rotor kit has been implemented, and two groups of high dimensional data vectors were been constructed by statistical parameter and wavelet package threshold entropy with the acquired vibration signals, and two groups of high dimensional vectors were reduced to 2 dimension vector by t-SNE method. By comparing, we validate that the extraction method of t-SNE dimension reduction of data based on high dimensional data constructed by Wavelet Packet Threshold Entropy is effective in distinguishing the fault features.
2016, 35(12): 1906-1913.
doi: 10.13433/j.cnki.1003-8728.2016.1217
Abstract:
For lightweight design of complex structures such as the cab of commercial vehicle, the finite element model of the cab is firstly built. In order to avoid blind optimization and improve design efficiency, the sensitivity analysis of the model is carried out to establish the contribution of the components to the cab's overall performance and the total mass. Then the evaluation methods of the relative sensitivity to select optimization variables is proposed, which simplified the process of variable selection. Finally, three structural optimization programs are raised based on different objectives:light quality programs, high stiffness programs and integrated programs; then comparing different optimization results of analysis, the comprehensive optimization program quickly has realized overall lightweight design goals for the cab.
For lightweight design of complex structures such as the cab of commercial vehicle, the finite element model of the cab is firstly built. In order to avoid blind optimization and improve design efficiency, the sensitivity analysis of the model is carried out to establish the contribution of the components to the cab's overall performance and the total mass. Then the evaluation methods of the relative sensitivity to select optimization variables is proposed, which simplified the process of variable selection. Finally, three structural optimization programs are raised based on different objectives:light quality programs, high stiffness programs and integrated programs; then comparing different optimization results of analysis, the comprehensive optimization program quickly has realized overall lightweight design goals for the cab.
2016, 35(12): 1914-1918.
doi: 10.13433/j.cnki.1003-8728.2016.1218
Abstract:
In order to improve the energy absorption characteristics of the hat-section beam under axial impact load, the design of stiffening plate is studied by using super-element theory and the experiments of dynamic testing rig. From the deformation pattern, crushing force curve and characteristic value of crushing, the advantages of multi-cellular structures have been proved and the structural design of the stiffening plate has been explored. A series of strategies for structural design of stiffening plate of hat-section beam under axial loading are proposed. The stiffening plate should be used to increase the amount of square unit cells, which should be set in the weak area in the hat-section beam so as to decrease the half wavelength of the holds by increasing the number of the super-folding element and decreasing its side-length. The present method will improve the energy absorption characteristics of the hat-section beam and increase the stability of the structure deformation.
In order to improve the energy absorption characteristics of the hat-section beam under axial impact load, the design of stiffening plate is studied by using super-element theory and the experiments of dynamic testing rig. From the deformation pattern, crushing force curve and characteristic value of crushing, the advantages of multi-cellular structures have been proved and the structural design of the stiffening plate has been explored. A series of strategies for structural design of stiffening plate of hat-section beam under axial loading are proposed. The stiffening plate should be used to increase the amount of square unit cells, which should be set in the weak area in the hat-section beam so as to decrease the half wavelength of the holds by increasing the number of the super-folding element and decreasing its side-length. The present method will improve the energy absorption characteristics of the hat-section beam and increase the stability of the structure deformation.
2016, 35(12): 1919-1924.
doi: 10.13433/j.cnki.1003-8728.2016.1219
Abstract:
To effectively isolate the vibration of automobile engine, the structure and working principle of an engine magnetorheological (MR) mount based on squeeze mode is developed, and magnetic circuit of MR mount is calculated according to the structure of MR mount and electromagnetic theory. Based on the axisymmetric characteristics of magnetic circuit, a magnetic circuit two-dimensional finite element simulation model is established with the MATLAB/PDEtool software, and the main structural parameters of magnetic circuit are determined according to the simulation analysis of static magnetic field. The mechanical model of MR mount is established according to magnetorheological fluid (MRF) Bingham model and hydrodynamic theory. The dynamic characteristics test of MR mount is carried out and the testing results are compared with the calculated results. The results show that they agree well, and the proposed design of MR mount based on squeeze mode is proved to be right.
To effectively isolate the vibration of automobile engine, the structure and working principle of an engine magnetorheological (MR) mount based on squeeze mode is developed, and magnetic circuit of MR mount is calculated according to the structure of MR mount and electromagnetic theory. Based on the axisymmetric characteristics of magnetic circuit, a magnetic circuit two-dimensional finite element simulation model is established with the MATLAB/PDEtool software, and the main structural parameters of magnetic circuit are determined according to the simulation analysis of static magnetic field. The mechanical model of MR mount is established according to magnetorheological fluid (MRF) Bingham model and hydrodynamic theory. The dynamic characteristics test of MR mount is carried out and the testing results are compared with the calculated results. The results show that they agree well, and the proposed design of MR mount based on squeeze mode is proved to be right.
2016, 35(12): 1925-1929.
doi: 10.13433/j.cnki.1003-8728.2016.1220
Abstract:
This paper presents a simplified method of designing the shearing valve type magnetorheological(MR) fluid damper based on experience. To design its magnetic circuit, it uses the existing design to preset a damping channel length in the first place; then according to the basic equation of damper structural design and the magnetic field channel saturation principle, the basic parameters of the structure of the fluid damper are determined. The paper also analyzes the relationship among the main performance parameters, designs the parameters of the MR fluid damper and puts forward a three-variable optimization model for the optimal size of the MR fluid damper. The results on comparing numerical simulation results with experimental results show that the simplified design method is simple and effective and can be used as a practical method for designing a shear valve type MR fluid damper.
This paper presents a simplified method of designing the shearing valve type magnetorheological(MR) fluid damper based on experience. To design its magnetic circuit, it uses the existing design to preset a damping channel length in the first place; then according to the basic equation of damper structural design and the magnetic field channel saturation principle, the basic parameters of the structure of the fluid damper are determined. The paper also analyzes the relationship among the main performance parameters, designs the parameters of the MR fluid damper and puts forward a three-variable optimization model for the optimal size of the MR fluid damper. The results on comparing numerical simulation results with experimental results show that the simplified design method is simple and effective and can be used as a practical method for designing a shear valve type MR fluid damper.
2016, 35(12): 1930-1936.
doi: 10.13433/j.cnki.1003-8728.2016.1221
Abstract:
Two dimensional finite element models were established via ABAQUS software in this paper. In view of dynamic problems involving large deformation in sinking, the arbitrary Lagrangian-Eulerian (ALE) method was used to describe the interaction between foot and soil, and the traced points were created to record the trajectories of soil particles. The radial and vertical displacement of traced points and the soil's density field distribution at different sinking depth were extracted to study the soil squeezing effect under the sole of foot. By analyzing the variation of the distribution of principal stress vectors, radial and vertical stress distribution, soil arching effect caused by the third principal stress was found under the vertical plane strain condition. Due to the deflection of the principal stress vectors, the third principal stresses overlap respectively in the radial and vertical directions, leading to the peaking values of the radical and vertical stress in the central axis respectively of the radical and vertical stress in the central axis.
Two dimensional finite element models were established via ABAQUS software in this paper. In view of dynamic problems involving large deformation in sinking, the arbitrary Lagrangian-Eulerian (ALE) method was used to describe the interaction between foot and soil, and the traced points were created to record the trajectories of soil particles. The radial and vertical displacement of traced points and the soil's density field distribution at different sinking depth were extracted to study the soil squeezing effect under the sole of foot. By analyzing the variation of the distribution of principal stress vectors, radial and vertical stress distribution, soil arching effect caused by the third principal stress was found under the vertical plane strain condition. Due to the deflection of the principal stress vectors, the third principal stresses overlap respectively in the radial and vertical directions, leading to the peaking values of the radical and vertical stress in the central axis respectively of the radical and vertical stress in the central axis.
2016, 35(12): 1937-1943.
doi: 10.13433/j.cnki.1003-8728.2016.1222
Abstract:
Active suspension needs too much energy to generate an active control force. In order to overcome the shortcoming, a kind of self-powered active suspension system based on the EHA (electro-hydrostatic actuator) was proposed and designed. The models of the active mode and regeneration mode were respectively established. The energy balance condition of the EHA self-powered active suspension system was analyzed. The coordinated switching control strategies which included upper switch controller and lower sky-hook were designed. The effects of the sky-hook damping coefficient on improving suspension performances and realizing the self-powered were analyzed with the simulation method. And the reasonable sky-hook damping coefficient was designed. The results show that the self-powered EHA active suspension system can completely realize self-powered and improve the suspension performances, which effectively overcomes the defect of active suspension with high energy consumption.
Active suspension needs too much energy to generate an active control force. In order to overcome the shortcoming, a kind of self-powered active suspension system based on the EHA (electro-hydrostatic actuator) was proposed and designed. The models of the active mode and regeneration mode were respectively established. The energy balance condition of the EHA self-powered active suspension system was analyzed. The coordinated switching control strategies which included upper switch controller and lower sky-hook were designed. The effects of the sky-hook damping coefficient on improving suspension performances and realizing the self-powered were analyzed with the simulation method. And the reasonable sky-hook damping coefficient was designed. The results show that the self-powered EHA active suspension system can completely realize self-powered and improve the suspension performances, which effectively overcomes the defect of active suspension with high energy consumption.
2016, 35(12): 1944-1949.
doi: 10.13433/j.cnki.1003-8728.2016.1223
Abstract:
For getting the constitutive parameters of composite material, comparing with the traditional electrical measuring method, this paper proposes an parameter estimation technique based on digital image correlation technique (DIC), which solves the easily interfered issue at the time of measuring parameters. In view of the carbon fiber composites, which is used the body and chassis of vehicles, as the subject of study. Firstly, the parameter estimation technique obtains the whole displacement field of the composite specimens with the test apparatuses of DIC. Then, combining with finite element method (FEM), the parameter estimation problem model is established through the error function between the measured and the simulated results. Finally, in order to find the optimal result, the paper combines the genetic algorithm (GA) with the sequential quadratic programming (SQP) to represent the real composite material constitutive parameters. The experiment shows that the ability of the proposed method is strong to identify the material constitutive parameters, especially the parameters in a larger interval range. Besides, the approach could identify complete composite material parameters by once, and has the superior precision and efficiency.
For getting the constitutive parameters of composite material, comparing with the traditional electrical measuring method, this paper proposes an parameter estimation technique based on digital image correlation technique (DIC), which solves the easily interfered issue at the time of measuring parameters. In view of the carbon fiber composites, which is used the body and chassis of vehicles, as the subject of study. Firstly, the parameter estimation technique obtains the whole displacement field of the composite specimens with the test apparatuses of DIC. Then, combining with finite element method (FEM), the parameter estimation problem model is established through the error function between the measured and the simulated results. Finally, in order to find the optimal result, the paper combines the genetic algorithm (GA) with the sequential quadratic programming (SQP) to represent the real composite material constitutive parameters. The experiment shows that the ability of the proposed method is strong to identify the material constitutive parameters, especially the parameters in a larger interval range. Besides, the approach could identify complete composite material parameters by once, and has the superior precision and efficiency.
2016, 35(12): 1950-1955.
doi: 10.13433/j.cnki.1003-8728.2016.1224
Abstract:
The relationship between instruction attitude angles and gimbal angles of three-axis turntable in the missile hardware-in-the-loop (HWIL) simulation is studied. To achieve the real attitude motion similarity, a method is proposed to make the gimbal output angular rate match with the turntable instruction angular rate all the time to realize the accurate simulation of missile attitude. Firstly, the coordinate system and attitude angles of missile, the coordinate system and attitude angles of turntable, and drive equation and attitude differential equation of two kinds of three-axis turntable (flight motion simulator based on vertical or horizontal outer axis stand) are introduced. The essence of attitude similarity is that the turntable output angular rate recurrent missile theoretical angular rate, and thus make the two attitude matrix similar. A horizontal turntable attitude angles setting method considering turntable rotation order that can ensure the attitude matrix similar any time is proposed. The method of attitude matrix similarity proposed definitudes the relationship between the missile attitude angles and gimbal angles of turntable, which can eliminate the bad effect of the improper gimbal structure of three-axis turntable effectively. The digital simulation result indicates that turntable gimbal structure has influence on recurrenting the theoretical angular rate when setting turntable instruction attitude angles and the proposed attitude angles setting method achieves attitude motion similarity. The HWIL simulation indicates the proposed method can solve the problem of attitude motion similarity efficiently in the HWIL simulation of hypersonic vehicle.
The relationship between instruction attitude angles and gimbal angles of three-axis turntable in the missile hardware-in-the-loop (HWIL) simulation is studied. To achieve the real attitude motion similarity, a method is proposed to make the gimbal output angular rate match with the turntable instruction angular rate all the time to realize the accurate simulation of missile attitude. Firstly, the coordinate system and attitude angles of missile, the coordinate system and attitude angles of turntable, and drive equation and attitude differential equation of two kinds of three-axis turntable (flight motion simulator based on vertical or horizontal outer axis stand) are introduced. The essence of attitude similarity is that the turntable output angular rate recurrent missile theoretical angular rate, and thus make the two attitude matrix similar. A horizontal turntable attitude angles setting method considering turntable rotation order that can ensure the attitude matrix similar any time is proposed. The method of attitude matrix similarity proposed definitudes the relationship between the missile attitude angles and gimbal angles of turntable, which can eliminate the bad effect of the improper gimbal structure of three-axis turntable effectively. The digital simulation result indicates that turntable gimbal structure has influence on recurrenting the theoretical angular rate when setting turntable instruction attitude angles and the proposed attitude angles setting method achieves attitude motion similarity. The HWIL simulation indicates the proposed method can solve the problem of attitude motion similarity efficiently in the HWIL simulation of hypersonic vehicle.
2016, 35(12): 1956-1960.
doi: 10.13433/j.cnki.1003-8728.2016.1225
Abstract:
Based on the small civil aircraft, three finite element models of fuselage section with different strut rigidity are developed by HyperMesh software. The impact characteristics of fuselage sections subjected to 7m/s vertical velocity are analyzed using the explicit, nonlinear transient-dynamic finite element code, LS-Dyna. A contrastive analysis on failure mode, energy absorption, velocity histories and acceleration histories of different fuselage sections is introduced. The results show that a too high or too low strut stiffness will bring threat to the survival of passengers. An advisable design of strut will impose an effective control on crash failure and reduce the dynamic response, which will finally improve the crashworthiness of aircraft.
Based on the small civil aircraft, three finite element models of fuselage section with different strut rigidity are developed by HyperMesh software. The impact characteristics of fuselage sections subjected to 7m/s vertical velocity are analyzed using the explicit, nonlinear transient-dynamic finite element code, LS-Dyna. A contrastive analysis on failure mode, energy absorption, velocity histories and acceleration histories of different fuselage sections is introduced. The results show that a too high or too low strut stiffness will bring threat to the survival of passengers. An advisable design of strut will impose an effective control on crash failure and reduce the dynamic response, which will finally improve the crashworthiness of aircraft.
2016, 35(12): 1961-1966.
doi: 10.13433/j.cnki.1003-8728.2016.1226
Abstract:
The visualization techniques are merged into aircraft conceptual design optimization to improve the efficiency of optimization formulation and enhance the rationality of the solution selection. The definition of optimization formulation is implemented with a MATLAB programming graphical interface, which greatly simplifies the optimization formulation. The scatter diagrams are used to monitor the optimization process, which helps one judge the rationality of the optimization formulation and algorithms. The visualization interface for optimization results consists of three graphs-a scatter diagram for objective space, a parallel coordinate for the parameters and a plot for constraint boundary, which contributes to an intuitive understanding of the object space, the parameter correlation, the feasible domain of design space and the distance between the optimal solution and the constraint boundary.
The visualization techniques are merged into aircraft conceptual design optimization to improve the efficiency of optimization formulation and enhance the rationality of the solution selection. The definition of optimization formulation is implemented with a MATLAB programming graphical interface, which greatly simplifies the optimization formulation. The scatter diagrams are used to monitor the optimization process, which helps one judge the rationality of the optimization formulation and algorithms. The visualization interface for optimization results consists of three graphs-a scatter diagram for objective space, a parallel coordinate for the parameters and a plot for constraint boundary, which contributes to an intuitive understanding of the object space, the parameter correlation, the feasible domain of design space and the distance between the optimal solution and the constraint boundary.
2016, 35(12): 1967-1974.
doi: 10.13433/j.cnki.1003-8728.2016.1227
Abstract:
China is striving to implement the lunar exploration, in Phase Ⅲ of the project, one of the main targets is to acquire lunar soil sample and bring it back to the earth, the sample is under lunar surface at a depth of two meters with original information. As an important part of drilling sampling device, design of drilling guiding mechanism is a key to ensure successful sampling. Based on its required functions, schematic diagrams are defined, then according to different styles of friction and contact, eight design projects of guideway are proposed. For the purpose of comprehensively evaluating the advantages and disadvantages of each project, analytic hierarchy process is used to establish an evaluation model and determine the evaluation indices. By calculations of judgment matrix and verification of consistency, the weight for each project is obtained and the best project can be determined, which provides a base for similar selection optimization.
China is striving to implement the lunar exploration, in Phase Ⅲ of the project, one of the main targets is to acquire lunar soil sample and bring it back to the earth, the sample is under lunar surface at a depth of two meters with original information. As an important part of drilling sampling device, design of drilling guiding mechanism is a key to ensure successful sampling. Based on its required functions, schematic diagrams are defined, then according to different styles of friction and contact, eight design projects of guideway are proposed. For the purpose of comprehensively evaluating the advantages and disadvantages of each project, analytic hierarchy process is used to establish an evaluation model and determine the evaluation indices. By calculations of judgment matrix and verification of consistency, the weight for each project is obtained and the best project can be determined, which provides a base for similar selection optimization.
