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RSS2013 Vol. 32, No. 5
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2013, 32(5): 625-630.
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Abstract:
In order to improve the automation degree of the satellite overall design, taking the aerospace satellite asexample, a method of model-driven for satellite overall design is proposed. Firstly, the model-driven process forsatellite overall design is analyzed. Secondly, the ontology knowledgebase for satellite overall design is constructed,which realizes formalizing description of the models. Thirdly, the models of requirement analysis, functional analysis and product structural analysis are constructed respectively. Taking the user requirement as input, the requirement analysis, functional analysis and product structural analysis can be dealt intelligently supported by the ontology knowledgebase, which provides a kind of intelligent modeling tool for model-based system engineering. At last,taking some a satellite as example, the effectiveness of this method is verified.
In order to improve the automation degree of the satellite overall design, taking the aerospace satellite asexample, a method of model-driven for satellite overall design is proposed. Firstly, the model-driven process forsatellite overall design is analyzed. Secondly, the ontology knowledgebase for satellite overall design is constructed,which realizes formalizing description of the models. Thirdly, the models of requirement analysis, functional analysis and product structural analysis are constructed respectively. Taking the user requirement as input, the requirement analysis, functional analysis and product structural analysis can be dealt intelligently supported by the ontology knowledgebase, which provides a kind of intelligent modeling tool for model-based system engineering. At last,taking some a satellite as example, the effectiveness of this method is verified.
2013, 32(5): 631-635.
Abstract:
Analysis vibration signals of bearing seat and nut seat with wavelet packet. Then take power spectrum ofwavelet packet to be characteristic parameters. By these parameters, study performance degradation of screw pairfor NC machine tool. Compare power spectrum of vibration in different feed rates and cutting depths, and try to findthe effect of feed rate and cutting depth on screw vibration. In order to evaluate performance of screw pair, buildperformance degradation model based on BP neural network. The input parameters include vibration, current signals of screw motor, feed rate, cutting depth and processing scheme, and the output of evaulation model is the result of performance degradion for screw pair. Tests show that the evauation results are important reference for maintance of scrwe pair.
Analysis vibration signals of bearing seat and nut seat with wavelet packet. Then take power spectrum ofwavelet packet to be characteristic parameters. By these parameters, study performance degradation of screw pairfor NC machine tool. Compare power spectrum of vibration in different feed rates and cutting depths, and try to findthe effect of feed rate and cutting depth on screw vibration. In order to evaluate performance of screw pair, buildperformance degradation model based on BP neural network. The input parameters include vibration, current signals of screw motor, feed rate, cutting depth and processing scheme, and the output of evaulation model is the result of performance degradion for screw pair. Tests show that the evauation results are important reference for maintance of scrwe pair.
2013, 32(5): 636-640.
Abstract:
In order to enhance the adaptability of the ride comfort optimization result under uncertainties when a vehicle is moving, the paper studies the 8-DOF vibration model of the whole vehicle and then sets up the MATLAB/SIMULINK model of its ride comfort. To improve the optimization calculation efficiency, the paper constructs theKriging model according to the simulation results. The mean square value of acceleration is taken as the objectivefunction; the suspension stiffness and nonlinear damping coefficients, the seat's stiffness and damping are taken asdesign variables; the quality of spring and the stiffness and damping of tires are taken as uncertainties and fuzziness. Using the fuzzy theory and the multi-population genetic algorithm, the double-nested uncertainty of the modelis optimized. The comparison indicates that when the range of uncertainty is varying, the optimization results reach2. 0 m/s2, far greater than the optimization results under uncertainty (1. 5 m/s2); that is to say, the optimizationresults under uncertainty have better adaptability.
In order to enhance the adaptability of the ride comfort optimization result under uncertainties when a vehicle is moving, the paper studies the 8-DOF vibration model of the whole vehicle and then sets up the MATLAB/SIMULINK model of its ride comfort. To improve the optimization calculation efficiency, the paper constructs theKriging model according to the simulation results. The mean square value of acceleration is taken as the objectivefunction; the suspension stiffness and nonlinear damping coefficients, the seat's stiffness and damping are taken asdesign variables; the quality of spring and the stiffness and damping of tires are taken as uncertainties and fuzziness. Using the fuzzy theory and the multi-population genetic algorithm, the double-nested uncertainty of the modelis optimized. The comparison indicates that when the range of uncertainty is varying, the optimization results reach2. 0 m/s2, far greater than the optimization results under uncertainty (1. 5 m/s2); that is to say, the optimizationresults under uncertainty have better adaptability.
2013, 32(5): 641-646.
Abstract:
Twin spool rotor systems are widely used in modern aircraft engines. In order to reduce the weight of the rotorsystem, an inter-bearing is also used to support one end of the high pressure (HP) rotor between the high pressure(HP) rotor and the low pressure (LP) rotor in a twin spool rotor system. This structure can reduce the weight of the rotor system but make the coupling between the high pressure (HP) rotor and the low pressure (LP) rotor stronger. Thispaper sets up a simple model for simulating the vibration features of such a twin spool rotor. In the model the stiffnessand damping of supports and inter-bearing are taken into account. The stiffness of the inter-bearing has an obvious influence on the vibration of the twin spool rotor. When the stiffness is anisotropic, the gravity of the rotor system will resultin a vibration of twice HP speed, a "gravity critical"will appear. The maneuvering of airplanes will lead to an apparentincrease in the level of vibration excited by gravity. The LP rotor unbalance will cause a vibration with a combined frequency, and a resonance will take place. When the HP rotor runs opposite to the LP rotor, there is also one combinedfrequency. It turns out when an anisotropic stiffness of inter-bearing exists, more vibration components and more resonances will appear, this is detrimental to safe and reliable operation of a twin spool rotor.
Twin spool rotor systems are widely used in modern aircraft engines. In order to reduce the weight of the rotorsystem, an inter-bearing is also used to support one end of the high pressure (HP) rotor between the high pressure(HP) rotor and the low pressure (LP) rotor in a twin spool rotor system. This structure can reduce the weight of the rotor system but make the coupling between the high pressure (HP) rotor and the low pressure (LP) rotor stronger. Thispaper sets up a simple model for simulating the vibration features of such a twin spool rotor. In the model the stiffnessand damping of supports and inter-bearing are taken into account. The stiffness of the inter-bearing has an obvious influence on the vibration of the twin spool rotor. When the stiffness is anisotropic, the gravity of the rotor system will resultin a vibration of twice HP speed, a "gravity critical"will appear. The maneuvering of airplanes will lead to an apparentincrease in the level of vibration excited by gravity. The LP rotor unbalance will cause a vibration with a combined frequency, and a resonance will take place. When the HP rotor runs opposite to the LP rotor, there is also one combinedfrequency. It turns out when an anisotropic stiffness of inter-bearing exists, more vibration components and more resonances will appear, this is detrimental to safe and reliable operation of a twin spool rotor.
2013, 32(5): 647-651.
Abstract:
In order to ensure the security and low noise of the aeronautic thin-spoke bevel gear, there should not belarge stress aroused by resonance existing in the range of operating speed. Thus it is necessary to modulate thestructural parameters of the gear spoke to assure that the travelling-wave resonance do not arise in the working conditions, at the same time, the mass should not be added. This study prepared the structural parameters by Orthogonal Experimental Design, and established the axial section model through parameterization, and computed the dynamic frequency by APDL (Ansys Programing Design Language), then founded the double latent BP ArtificialNeural Network and trained it to make it reflect the nonlinear relationship between the dynamic frequency and thestructural parameters. Finally, a set of parameters which avoided the travelling-wave resonance was calculated successfully, simultaneously, the mass of the gear was also decreased.
In order to ensure the security and low noise of the aeronautic thin-spoke bevel gear, there should not belarge stress aroused by resonance existing in the range of operating speed. Thus it is necessary to modulate thestructural parameters of the gear spoke to assure that the travelling-wave resonance do not arise in the working conditions, at the same time, the mass should not be added. This study prepared the structural parameters by Orthogonal Experimental Design, and established the axial section model through parameterization, and computed the dynamic frequency by APDL (Ansys Programing Design Language), then founded the double latent BP ArtificialNeural Network and trained it to make it reflect the nonlinear relationship between the dynamic frequency and thestructural parameters. Finally, a set of parameters which avoided the travelling-wave resonance was calculated successfully, simultaneously, the mass of the gear was also decreased.
2013, 32(5): 652-655.
Abstract:
A finite element contact analysis parametric model was established by ANSYS Workbench. The study onthe stress and deformation state in the flexible bearing with different radius coefficients has been conducted. Then,the deformation and contact stress state of the inner and outer rings of these flexible bearings were attained. The testresults show that the maximum equivalent and radial stresses appear in running tracks of both rings at the contactwith the ball placed on the major cam axis; the maximum equivalent stresses in both rings and the maximum contactpressures between the balls and the curve increase almost linearly with the increase of the groove curvature radiuscoefficients. The presented approach to a contact analysis of the flexible bearing can help the designer accuratelydetermine the maximum stress of the flexible bearing, which can then be used for its optimizations.
A finite element contact analysis parametric model was established by ANSYS Workbench. The study onthe stress and deformation state in the flexible bearing with different radius coefficients has been conducted. Then,the deformation and contact stress state of the inner and outer rings of these flexible bearings were attained. The testresults show that the maximum equivalent and radial stresses appear in running tracks of both rings at the contactwith the ball placed on the major cam axis; the maximum equivalent stresses in both rings and the maximum contactpressures between the balls and the curve increase almost linearly with the increase of the groove curvature radiuscoefficients. The presented approach to a contact analysis of the flexible bearing can help the designer accuratelydetermine the maximum stress of the flexible bearing, which can then be used for its optimizations.
2013, 32(5): 656-659.
Abstract:
In the discrete interpolation process, it' s difficult to realize trapezoidal velocity profile within a smallline, because the endpoint of the line can not be used as an interpolation point exactly. A new interpolation algorithm of small line is proposed in this paper to solve the above problems. In the algorithm, speed look-ahead startsfrom both the endpoints of the small line blocks to the middle, and speed-linking is implemented in the predetermined position. The transition speed can reach its peak value through forward planning and reverse confirming, andthen the speed of small line endpoints can be calculated. Finally according to the endpoint speed and length ofsmall lines, the whole speed processing can be accomplished by the method of small line speed planning based onvariable interpolation period. The simulation results demonstrate that the new algorithm can realize trapezoidal velocity profile in a discrete interpolation process and eliminates residual length of interpolation.
In the discrete interpolation process, it' s difficult to realize trapezoidal velocity profile within a smallline, because the endpoint of the line can not be used as an interpolation point exactly. A new interpolation algorithm of small line is proposed in this paper to solve the above problems. In the algorithm, speed look-ahead startsfrom both the endpoints of the small line blocks to the middle, and speed-linking is implemented in the predetermined position. The transition speed can reach its peak value through forward planning and reverse confirming, andthen the speed of small line endpoints can be calculated. Finally according to the endpoint speed and length ofsmall lines, the whole speed processing can be accomplished by the method of small line speed planning based onvariable interpolation period. The simulation results demonstrate that the new algorithm can realize trapezoidal velocity profile in a discrete interpolation process and eliminates residual length of interpolation.
2013, 32(5): 660-664.
Abstract:
A new prediction method of dynamic stiffness for the rubber isolator based on the finite element methodwas proposed. The relevant constitutive relationship model, finite element model and prediction process for dynamicstiffness were studied. A rubber isolator prediction for an IMU was performed, and the dynamic stiffness and damping values were thus obtained. The present stiffness and damping values were applied to a single freedom dynamicresponse analysis, the analysis results of dynamic response are consistent with the testing results. Moreover, thehigh frequency resonance due to dynamic stiffness changes can be calculated during the middle and high frequencyby using the stiffness prediction method, which indicates the method has higher calculation precision comparingwith traditional prediction methods of static stiffness.
A new prediction method of dynamic stiffness for the rubber isolator based on the finite element methodwas proposed. The relevant constitutive relationship model, finite element model and prediction process for dynamicstiffness were studied. A rubber isolator prediction for an IMU was performed, and the dynamic stiffness and damping values were thus obtained. The present stiffness and damping values were applied to a single freedom dynamicresponse analysis, the analysis results of dynamic response are consistent with the testing results. Moreover, thehigh frequency resonance due to dynamic stiffness changes can be calculated during the middle and high frequencyby using the stiffness prediction method, which indicates the method has higher calculation precision comparingwith traditional prediction methods of static stiffness.
2013, 32(5): 665-669.
Abstract:
This paper improves the element independent corotaional (EICR) formula, with which it is not necessary to derive the stillness of materials in the local corotational coordinate system. The formula can extend the existingrobust linear beam element to deal with the arbitrarily large rotation in the geometrical nonlinear analysis of 2-D corotational Timoshenko beam element. Meanwhile the load stiffness that results from follower load was deduced, andthe high convergence speed was retained. The geometrical nonlinear analysis of one of the Timoshenko beam elements was carried out, using the EICR formula. The numerical example shows that the corotaional Timoshenkobeam element analysis method is accurate, efficient and applicable to the geometrically nonlinear optimization of a2-D beam structure.
This paper improves the element independent corotaional (EICR) formula, with which it is not necessary to derive the stillness of materials in the local corotational coordinate system. The formula can extend the existingrobust linear beam element to deal with the arbitrarily large rotation in the geometrical nonlinear analysis of 2-D corotational Timoshenko beam element. Meanwhile the load stiffness that results from follower load was deduced, andthe high convergence speed was retained. The geometrical nonlinear analysis of one of the Timoshenko beam elements was carried out, using the EICR formula. The numerical example shows that the corotaional Timoshenkobeam element analysis method is accurate, efficient and applicable to the geometrically nonlinear optimization of a2-D beam structure.
2013, 32(5): 670-674.
Abstract:
This paper analyzed the characteristics and disadvantages of the common energy storage ways in HEV(hybrid electrical vehicle) and pointed out that the flywheel battery will have good prospects in HEV. Then thispaper introduced the basic principles of the flywheel battery. Through the comparative analysis, the paper arguedthat the ultra-high strength steel flywheel rotor have comprehensive advantages comparing with the composite materials one at a speed of 20 000 r/min. The paper established the mathematical model to optimize the structure of theflywheel. Using this model and with the help of Matlab, this paper calculated the basic parameters of the flywheel.Furthermore, based on the finite element analysis software Abaqus, the paper optimized the mechanical structure ofthe flywheel rotor storing energy of 1 kW穐.
This paper analyzed the characteristics and disadvantages of the common energy storage ways in HEV(hybrid electrical vehicle) and pointed out that the flywheel battery will have good prospects in HEV. Then thispaper introduced the basic principles of the flywheel battery. Through the comparative analysis, the paper arguedthat the ultra-high strength steel flywheel rotor have comprehensive advantages comparing with the composite materials one at a speed of 20 000 r/min. The paper established the mathematical model to optimize the structure of theflywheel. Using this model and with the help of Matlab, this paper calculated the basic parameters of the flywheel.Furthermore, based on the finite element analysis software Abaqus, the paper optimized the mechanical structure ofthe flywheel rotor storing energy of 1 kW穐.
2013, 32(5): 675-678.
Abstract:
Study on the tribological properties of a prepared novel zero-sulphur/phosphorus nitrogen-containing heteocyclic lubricating additive in the base oil of liquid paraffin is made by four-ball tester, ring-block test machineand all-purpose tribometer, the topographies and chemical characteristics of the worn steel-ball surfaces are analyzed by means of scanning electron microscope and X-ray photoelectron spectroscopy. The resulsts indicate that theadditive can evidently enhance the load-carrying capacity of the base oil, reduce the wear-scar dameter in long-timefriction test and diminish the coefficient of friction in block-on-ring test. It is supposed that the additive reacts withthe steel surfaces during the rubbing process and generates a tribochemical reaction film mainly composed of ferrousoxide, organic containing-nitrogen compounds and nitrogen-containing metallic chelate, which is effective on improving the friction and wear characteristcs of the base oil.
Study on the tribological properties of a prepared novel zero-sulphur/phosphorus nitrogen-containing heteocyclic lubricating additive in the base oil of liquid paraffin is made by four-ball tester, ring-block test machineand all-purpose tribometer, the topographies and chemical characteristics of the worn steel-ball surfaces are analyzed by means of scanning electron microscope and X-ray photoelectron spectroscopy. The resulsts indicate that theadditive can evidently enhance the load-carrying capacity of the base oil, reduce the wear-scar dameter in long-timefriction test and diminish the coefficient of friction in block-on-ring test. It is supposed that the additive reacts withthe steel surfaces during the rubbing process and generates a tribochemical reaction film mainly composed of ferrousoxide, organic containing-nitrogen compounds and nitrogen-containing metallic chelate, which is effective on improving the friction and wear characteristcs of the base oil.
2013, 32(5): 679-682.
Abstract:
Based on the hinge four-bar mechanism in small handling device, a new method of motion reliability isproposed. The original length size error, the hinge joint-gap error and wear allowance error are considered as random variables. In the assumption that the influence factors are normal distributed, the mathematical models andcomputer programming calculation are carried out. By improving the effective length of the model theory, a new effective length model of continuous contact is established. According to the Archard's wear theory, a new motionpair model is created for the analysis of movement and stress. Using the Matlab software to program and calculate,the quantitative analysis of the above factors shows the influence on output displacement reliability of the handlingarm. The present method is more accurate and closer to engineering practice.
Based on the hinge four-bar mechanism in small handling device, a new method of motion reliability isproposed. The original length size error, the hinge joint-gap error and wear allowance error are considered as random variables. In the assumption that the influence factors are normal distributed, the mathematical models andcomputer programming calculation are carried out. By improving the effective length of the model theory, a new effective length model of continuous contact is established. According to the Archard's wear theory, a new motionpair model is created for the analysis of movement and stress. Using the Matlab software to program and calculate,the quantitative analysis of the above factors shows the influence on output displacement reliability of the handlingarm. The present method is more accurate and closer to engineering practice.
2013, 32(5): 683-687.
Abstract:
We explain the causes of the superfluous force of a vehicle steering mechatronic test bench. The superfluous force is one of the main factors that affects the precision of a control system. The physical model of the testbench was constructed by using the hydraulic control principle. Its mathematical model was established by usingservo amplifier, electro-hydraulic servo valve, valve cylinder and force sensor. The superfluous force of its loadingsystem was restrained by setting a feed-forward compensator according to the structure-invariant theory. We simulateand contrast the test bench with the feed-forward compensator through using MATLAB; the simulation results andtheir contrast show that the test bench meets its performance indexes. The experimental results on actual force showthat the superfluous force of the loading system is effectively restrained.
We explain the causes of the superfluous force of a vehicle steering mechatronic test bench. The superfluous force is one of the main factors that affects the precision of a control system. The physical model of the testbench was constructed by using the hydraulic control principle. Its mathematical model was established by usingservo amplifier, electro-hydraulic servo valve, valve cylinder and force sensor. The superfluous force of its loadingsystem was restrained by setting a feed-forward compensator according to the structure-invariant theory. We simulateand contrast the test bench with the feed-forward compensator through using MATLAB; the simulation results andtheir contrast show that the test bench meets its performance indexes. The experimental results on actual force showthat the superfluous force of the loading system is effectively restrained.
2013, 32(5): 688-692.
Abstract:
Exoskeleton is composed of rigid parts and several hydraulic cylinders. Many damping components areset in exoskeleton for better reducing vibration and absorbing impact. In this paper, exoskeleton is regarded as acoupling structure of the rigid parts with many flexible parts. ANSYS is used to establish exoskeleton's finite element model by the rigid-flexible coupling method, and stress analysis and modal analysis for exoskeleton are doneunder several motion conditions for getting stress, vibration mode and natural frequency. In the analysis exoskeletonis loaded 60kg. All components meet the static strength requirements except the ankle structure that should bestrengthened from the result of stress analysis. Exoskeleton avoids the frequency of human back-forth motion, but it's easy to resonate from side to side by the result of modal analysis.
Exoskeleton is composed of rigid parts and several hydraulic cylinders. Many damping components areset in exoskeleton for better reducing vibration and absorbing impact. In this paper, exoskeleton is regarded as acoupling structure of the rigid parts with many flexible parts. ANSYS is used to establish exoskeleton's finite element model by the rigid-flexible coupling method, and stress analysis and modal analysis for exoskeleton are doneunder several motion conditions for getting stress, vibration mode and natural frequency. In the analysis exoskeletonis loaded 60kg. All components meet the static strength requirements except the ankle structure that should bestrengthened from the result of stress analysis. Exoskeleton avoids the frequency of human back-forth motion, but it's easy to resonate from side to side by the result of modal analysis.
2013, 32(5): 693-698.
Abstract:
According to the characteristic of roller bearing contact problem, the Hertz contact theory is used to revise the contact widths of rollers with inner race and outer race of bearing with the Boundary Element Method(BEM). The program for three dimensional elastic contact and friction problem is built. Use this program the loaddistribution of mill conical roller bearing is simulated. The shaft block direct measure method is used to measureload distribution of the four-row conical bearing. The numerical simulations of load distribution agree well with experimental data which proves the validity and effectiveness of using BEM to solve the load distribution of bearing.
According to the characteristic of roller bearing contact problem, the Hertz contact theory is used to revise the contact widths of rollers with inner race and outer race of bearing with the Boundary Element Method(BEM). The program for three dimensional elastic contact and friction problem is built. Use this program the loaddistribution of mill conical roller bearing is simulated. The shaft block direct measure method is used to measureload distribution of the four-row conical bearing. The numerical simulations of load distribution agree well with experimental data which proves the validity and effectiveness of using BEM to solve the load distribution of bearing.
2013, 32(5): 699-703.
Abstract:
Facing the requirements for crashworthiness design of transport aircraft composite fuselage section, theeffects of composite skin on crashworthiness of composite fuselage section have been studied. This paper establishesthe finite element model of composite fuselage section in HyperMesh, and analyzes the dynamic response characteristics of composite fuselage section subjected to impact with the vertical velocity of 6. 67m/s by changing compositeply angles and plies in LS-DYNA. The data of deformation, displacement, strain and stress are obtained. The acceleration history curves and failure modes of fuselage section under different conditions are given. The results showthat a seat's peak overload can be significantly reduced by selecting appropriate composite ply angles and plies, andthe crashworthiness of composite fuselage section can be effectively improved.
Facing the requirements for crashworthiness design of transport aircraft composite fuselage section, theeffects of composite skin on crashworthiness of composite fuselage section have been studied. This paper establishesthe finite element model of composite fuselage section in HyperMesh, and analyzes the dynamic response characteristics of composite fuselage section subjected to impact with the vertical velocity of 6. 67m/s by changing compositeply angles and plies in LS-DYNA. The data of deformation, displacement, strain and stress are obtained. The acceleration history curves and failure modes of fuselage section under different conditions are given. The results showthat a seat's peak overload can be significantly reduced by selecting appropriate composite ply angles and plies, andthe crashworthiness of composite fuselage section can be effectively improved.
2013, 32(5): 704-708.
Abstract:
The initial spark advance needs to be re-calibrated after the two stroke gasoline engine burning aviationkerosene. The numerical model of two-stroke kerosene engine is established using GT-Power. The influences of theengine speed, load, inlet air pressure, inlet air temperature and air-fuel ratio on spark advance are analyzed, andthen the conclusion is reached that the influence of inlet air temperature on spark advance is obvious except for theinfluence factors of engine speed and load. Finally, through numerical calculation, initial spark advance MAP under different working conditions is obtained based on power performance without regard to emissions and economicperformance. The experimental results are in consistent with the simulation results.
The initial spark advance needs to be re-calibrated after the two stroke gasoline engine burning aviationkerosene. The numerical model of two-stroke kerosene engine is established using GT-Power. The influences of theengine speed, load, inlet air pressure, inlet air temperature and air-fuel ratio on spark advance are analyzed, andthen the conclusion is reached that the influence of inlet air temperature on spark advance is obvious except for theinfluence factors of engine speed and load. Finally, through numerical calculation, initial spark advance MAP under different working conditions is obtained based on power performance without regard to emissions and economicperformance. The experimental results are in consistent with the simulation results.
2013, 32(5): 709-713.
Abstract:
A 4-RRUR parallel mechanism has fast motion and high stiffness and can be used to achieve the rapidsorting of goods and high-precision assembly. Firstly, the spiral system of each branch of the 4-RRUR parallelmechanism is set up by using the spiral theory. On this basis, we calculate the parallel mechanism with 4 degreesof freedom and select its drive input. Then we apply the vector matrix representation method to establishing the relationship between the input and output of each kinematic pair of the 4-RRUR parallel mechanism according to theidea of virtual mechanism. We use the equations which are only related to the main movements of each branch ofthe parallel mechanism to obtain the first order and second order kinematic influence coefficients of the parallelmechanism that correspond to the generalized coordinates. The velocity analysis and acceleration analysis areexpressed in an explicit way.
A 4-RRUR parallel mechanism has fast motion and high stiffness and can be used to achieve the rapidsorting of goods and high-precision assembly. Firstly, the spiral system of each branch of the 4-RRUR parallelmechanism is set up by using the spiral theory. On this basis, we calculate the parallel mechanism with 4 degreesof freedom and select its drive input. Then we apply the vector matrix representation method to establishing the relationship between the input and output of each kinematic pair of the 4-RRUR parallel mechanism according to theidea of virtual mechanism. We use the equations which are only related to the main movements of each branch ofthe parallel mechanism to obtain the first order and second order kinematic influence coefficients of the parallelmechanism that correspond to the generalized coordinates. The velocity analysis and acceleration analysis areexpressed in an explicit way.
2013, 32(5): 714-717.
Abstract:
The offshore wind turbine (OWT) tower is located in the complex marine environment, and it is subjectto wind load, wave load, seawater corrosion and so on. In order to ensure the reliable operation in the life cycle oftower, the Nantong coastal 2. 5 MW OWT tower at the service condition of particular sea areas is analyzed as follows: the structural shape of the tower and combining load characteristics of wind and wave under a single workingcondition are discussed; the fatigue testing program of the tower material Q345D is designed, and the S-N curveunder the seawater corrosion is obtained; the transient structural analysis and fatigue life prediction of the tower areperformed by using the ANSYS Workbench. The result shows that the estimated service life of 46 years is more thanthe design life of 20 years for 2. 5MW OWT tower, which can ensure the reliable work of OWT.
The offshore wind turbine (OWT) tower is located in the complex marine environment, and it is subjectto wind load, wave load, seawater corrosion and so on. In order to ensure the reliable operation in the life cycle oftower, the Nantong coastal 2. 5 MW OWT tower at the service condition of particular sea areas is analyzed as follows: the structural shape of the tower and combining load characteristics of wind and wave under a single workingcondition are discussed; the fatigue testing program of the tower material Q345D is designed, and the S-N curveunder the seawater corrosion is obtained; the transient structural analysis and fatigue life prediction of the tower areperformed by using the ANSYS Workbench. The result shows that the estimated service life of 46 years is more thanthe design life of 20 years for 2. 5MW OWT tower, which can ensure the reliable work of OWT.
2013, 32(5): 718-720.
Abstract:
Rotary machinery is the core equipment in the petrochemical production. Maintenance is an importantmeans to ensure the normal operation of rotary machinery. In order to effectively cut down the maintenance cost,taking the least equipment management cost within unit time as the target, a maintenance optimization model basedon monotonous geometric process was established, which can be applied to many types of life distribution and predictoptimal life cycle of machinery. In this model, firstly, the cost rate model of equipment management was obtainedon the basis of monotonous geometric process. And then, the Monte Carlo simulation method was introduced intothis model. Finally, the simulation program was designed by the Matlab software. A centrifugal pump with Weibulldistribution of two parameters was analyzed as a study case.
Rotary machinery is the core equipment in the petrochemical production. Maintenance is an importantmeans to ensure the normal operation of rotary machinery. In order to effectively cut down the maintenance cost,taking the least equipment management cost within unit time as the target, a maintenance optimization model basedon monotonous geometric process was established, which can be applied to many types of life distribution and predictoptimal life cycle of machinery. In this model, firstly, the cost rate model of equipment management was obtainedon the basis of monotonous geometric process. And then, the Monte Carlo simulation method was introduced intothis model. Finally, the simulation program was designed by the Matlab software. A centrifugal pump with Weibulldistribution of two parameters was analyzed as a study case.
2013, 32(5): 721-725.
Abstract:
Focusing on the deposit uniformity control that plays a key role in the laminated template electroforming,a friction-assisted pulsed electrodepositing technology was developed in this paper as well as its experimental device. According to the experimental method, a number of hard particles (ceramic beads) fill in space between theelectrodes and are propelled by mandrel's rotating movement to allow continuous impinging and grinding to the cathode surface, as an effort to instantaneously eliminating boundary effect that is caused by uneven current distribution. In comparison of the finish surface morphology and deposit thickness among the samples obtained respectivelyby traditional and new ways, the experimental results showed that the assistant friction could effectively remove thesediment and tumor along surface and provide a relatively flat layer with Ra 0. 253 μm. It indicates that the hardparticle-friction has highly practical value in the prototyping of laminated electroforming.
Focusing on the deposit uniformity control that plays a key role in the laminated template electroforming,a friction-assisted pulsed electrodepositing technology was developed in this paper as well as its experimental device. According to the experimental method, a number of hard particles (ceramic beads) fill in space between theelectrodes and are propelled by mandrel's rotating movement to allow continuous impinging and grinding to the cathode surface, as an effort to instantaneously eliminating boundary effect that is caused by uneven current distribution. In comparison of the finish surface morphology and deposit thickness among the samples obtained respectivelyby traditional and new ways, the experimental results showed that the assistant friction could effectively remove thesediment and tumor along surface and provide a relatively flat layer with Ra 0. 253 μm. It indicates that the hardparticle-friction has highly practical value in the prototyping of laminated electroforming.
2013, 32(5): 726-728.
Abstract:
Being one of the key indicators of a vehicle's performance, its brake performance is directly related totraffic safety, which depends largely on the brake performance. A brake tester is a device for testing the performance and quality of the brake. Therefore, we aim at reducing its structural design and manufacturing costs, improving its measurement accuracy and simplifying its structure. At present, the brake tester's structure has two forms:mechanical and electrical inertia. But the two forms have their own shortcomings. In light of this, we explore theimplementation of hydraulic inertia simulation and analyze its feasibility and significance. For the first time, we putforward the concept"hydraulic inertia".
Being one of the key indicators of a vehicle's performance, its brake performance is directly related totraffic safety, which depends largely on the brake performance. A brake tester is a device for testing the performance and quality of the brake. Therefore, we aim at reducing its structural design and manufacturing costs, improving its measurement accuracy and simplifying its structure. At present, the brake tester's structure has two forms:mechanical and electrical inertia. But the two forms have their own shortcomings. In light of this, we explore theimplementation of hydraulic inertia simulation and analyze its feasibility and significance. For the first time, we putforward the concept"hydraulic inertia".
2013, 32(5): 729-732.
Abstract:
At first, the theory of classical probabilistic neural network (PNN) as a pattern classification is discussed, and then an improved probabilistic neural network (IPNN) is proposed for solving the problem of low recognition rate which often exists in PNN, because PNN uses a same smooth factor during diagnosis procession. InIPNN, the smooth factor changes adaptively according to different categories of modes, so hidden neurons have highadaptabilities for function approximation, which better expresses the correlations between feature vectors and its pattern, better reflects the actual function of input feature vectors with final correct classification results. Secondly,IPNN is used in fault diagnosis of roller bearings. Experimental results show that IPNN can effectively improve theaccuracies of the rolling bearing fault classification and it has a higher recognition rate than PNN and backpropagation neural network (BPNN).
At first, the theory of classical probabilistic neural network (PNN) as a pattern classification is discussed, and then an improved probabilistic neural network (IPNN) is proposed for solving the problem of low recognition rate which often exists in PNN, because PNN uses a same smooth factor during diagnosis procession. InIPNN, the smooth factor changes adaptively according to different categories of modes, so hidden neurons have highadaptabilities for function approximation, which better expresses the correlations between feature vectors and its pattern, better reflects the actual function of input feature vectors with final correct classification results. Secondly,IPNN is used in fault diagnosis of roller bearings. Experimental results show that IPNN can effectively improve theaccuracies of the rolling bearing fault classification and it has a higher recognition rate than PNN and backpropagation neural network (BPNN).
2013, 32(5): 733-738.
Abstract:
In mining the thick coal seam and inclination coal seam, to maintain the stability of a hydraulic supportbecomes more and more important. First, the paper suggests the simplified model of the hydraulic support using abeam and plate. The correctness of the simplified model has been verified by comparing the quality and center position. Second, the vertical and horizontal stability of the hydraulic support was studied. The stability coefficients fordescribing the vertical and horizontal slippage and dumping of the hydraulic support were proposed. TakingZY10800/28/63 D large hydraulic support as an example, the influences of geometric parameters and load parameters on the stability coefficient were analyzed, and the reason of the instability was pointed out. Finally, accordingto the dumping and slippage characteristics of the hydraulic support, its control conditions on mining face were alsostudied.
In mining the thick coal seam and inclination coal seam, to maintain the stability of a hydraulic supportbecomes more and more important. First, the paper suggests the simplified model of the hydraulic support using abeam and plate. The correctness of the simplified model has been verified by comparing the quality and center position. Second, the vertical and horizontal stability of the hydraulic support was studied. The stability coefficients fordescribing the vertical and horizontal slippage and dumping of the hydraulic support were proposed. TakingZY10800/28/63 D large hydraulic support as an example, the influences of geometric parameters and load parameters on the stability coefficient were analyzed, and the reason of the instability was pointed out. Finally, accordingto the dumping and slippage characteristics of the hydraulic support, its control conditions on mining face were alsostudied.
2013, 32(5): 739-743.
Abstract:
To reduce the elastic deformation and vibration of a camshaft while grinding, the adjacent 3-dot gradualfitting method for its contour curve is put forward; the camshaft's 3 D model is established by using the ANSYS parametric design language (APDL). The deformation at different positions and different angles is deduced and analyzed with the finite element method. The natural frequency, the vibration mode and the harmonic response of thecamshaft while grinding is analyzed. The grinding parameter selection principle, through which the deformation ofthe camshaft may be reduced, is proposed. The camshaft's 3 D model can be established quickly and accuratelywith the 3-dot gradual fitting method; the elastic deformation and vibration can be reduced when the grinding parameters are selected appropriately; the precision and lift precision of the camshaft contour can be enhanced.
To reduce the elastic deformation and vibration of a camshaft while grinding, the adjacent 3-dot gradualfitting method for its contour curve is put forward; the camshaft's 3 D model is established by using the ANSYS parametric design language (APDL). The deformation at different positions and different angles is deduced and analyzed with the finite element method. The natural frequency, the vibration mode and the harmonic response of thecamshaft while grinding is analyzed. The grinding parameter selection principle, through which the deformation ofthe camshaft may be reduced, is proposed. The camshaft's 3 D model can be established quickly and accuratelywith the 3-dot gradual fitting method; the elastic deformation and vibration can be reduced when the grinding parameters are selected appropriately; the precision and lift precision of the camshaft contour can be enhanced.
2013, 32(5): 744-746,750.
Abstract:
The three waste plastic films including Polyethylene, Polyvinyl chloride and Polyester, in which are themain components of our country city life garbage, are selected as the research object. the suspension velocity formula meeting the actual diameter of particle can obtained by using the different Reynolds number to identify theplastic particle diameter range, and then the suspension velocity are calculated. In the separation chamber, brokenwaste plastic film as a particle, established relatively precise kinematic and kinetic equation. By using the MATLAB software programming, the plastic film motion trajectory is optimized and the optimal value of the plastic landing position are obtained. The initial speed and angle, the airflow velocity and angle are respectively 0. 122 0 m/s,9. 407 0� 1. 784 7 m/s, 6. 219 7�
The three waste plastic films including Polyethylene, Polyvinyl chloride and Polyester, in which are themain components of our country city life garbage, are selected as the research object. the suspension velocity formula meeting the actual diameter of particle can obtained by using the different Reynolds number to identify theplastic particle diameter range, and then the suspension velocity are calculated. In the separation chamber, brokenwaste plastic film as a particle, established relatively precise kinematic and kinetic equation. By using the MATLAB software programming, the plastic film motion trajectory is optimized and the optimal value of the plastic landing position are obtained. The initial speed and angle, the airflow velocity and angle are respectively 0. 122 0 m/s,9. 407 0� 1. 784 7 m/s, 6. 219 7�
2013, 32(5): 747-750.
Abstract:
The control method for the HEV propulsion system based on the dynamic process is proposed (theDPCM method). The experimental system has been built on the base of the DPCM method. The controlling effect ofthe DPCM method is validated by the experimental system. Based on the vehicle-transmission-test-bed experiments,the HEV dynamic characteristics at different loading rules are compared, which helps to validate that the methodadvanced in this dissertation succeeds in optimizing the dynamic characteristics of the HEV and restricting the energy consumption. The experiments prove the DPCM method can help the optimized target of the control strategy to beimplemented.
The control method for the HEV propulsion system based on the dynamic process is proposed (theDPCM method). The experimental system has been built on the base of the DPCM method. The controlling effect ofthe DPCM method is validated by the experimental system. Based on the vehicle-transmission-test-bed experiments,the HEV dynamic characteristics at different loading rules are compared, which helps to validate that the methodadvanced in this dissertation succeeds in optimizing the dynamic characteristics of the HEV and restricting the energy consumption. The experiments prove the DPCM method can help the optimized target of the control strategy to beimplemented.
2013, 32(5): 751-755,761.
Abstract:
In order to improve the dry clutch engagement quality during its launching process, a 2-DOF dynamicsmodel of the dry clutch driveline was built, and the synchronization lurch of dry clutch engagement during launching process was analyzed. Theoretical and experimental results show that the amplitude of dry clutch synchronizationlurch depends on the relationship of the friction torque, engine torque and load torque before synchronization instant. Compared with the engine torque and the load torque, the amplitude of dry clutch synchronization lurchwould increase when the friction torque before synchronization instant is too large. The amplitude of synchronizationlurch can be reduced effectively by properly decreasing the friction torque according to the engine torque and theload torque before synchronization instant.
In order to improve the dry clutch engagement quality during its launching process, a 2-DOF dynamicsmodel of the dry clutch driveline was built, and the synchronization lurch of dry clutch engagement during launching process was analyzed. Theoretical and experimental results show that the amplitude of dry clutch synchronizationlurch depends on the relationship of the friction torque, engine torque and load torque before synchronization instant. Compared with the engine torque and the load torque, the amplitude of dry clutch synchronization lurchwould increase when the friction torque before synchronization instant is too large. The amplitude of synchronizationlurch can be reduced effectively by properly decreasing the friction torque according to the engine torque and theload torque before synchronization instant.
2013, 32(5): 756-761.
Abstract:
To clarify the mechanism and action of air injection method on air lift characteristics, the river sand wassimulated as underground ore bed, the effects of stomata numbers and injection angles on water flux, mass flow rateof solids and overall efficiency are studied experimentally at a given constant submergence ratio and solid particlesare supplied by using small sediment transport system. The results are as follows: the water flux, mass flow rate ofsolids and overall efficiency showed no monotonicity with the increase in the air flow rate under any air injectionmethod; the positions for peak values of the former two were nearly close and moved to a right shift compared withthose of overall efficiency. The stomata numbers and injection angles have a little influence on water flux and massflow rate of solids, being slightly disadvantageous over overall efficiency. Taken as a whole, the curve lines, whichcorrespond to the stomata number and injection angle of 4 and 90�respectively, are higher compared with other airinjection methods. In addition, the gas Froude numbers corresponding to the efficiency of lifting solids are all closeto 2. 5 under any operation conditions and increase with the increase in the inner diameter of a lifting pipe.
To clarify the mechanism and action of air injection method on air lift characteristics, the river sand wassimulated as underground ore bed, the effects of stomata numbers and injection angles on water flux, mass flow rateof solids and overall efficiency are studied experimentally at a given constant submergence ratio and solid particlesare supplied by using small sediment transport system. The results are as follows: the water flux, mass flow rate ofsolids and overall efficiency showed no monotonicity with the increase in the air flow rate under any air injectionmethod; the positions for peak values of the former two were nearly close and moved to a right shift compared withthose of overall efficiency. The stomata numbers and injection angles have a little influence on water flux and massflow rate of solids, being slightly disadvantageous over overall efficiency. Taken as a whole, the curve lines, whichcorrespond to the stomata number and injection angle of 4 and 90�respectively, are higher compared with other airinjection methods. In addition, the gas Froude numbers corresponding to the efficiency of lifting solids are all closeto 2. 5 under any operation conditions and increase with the increase in the inner diameter of a lifting pipe.
2013, 32(5): 762-765.
Abstract:
To the micro-assembly robot hand-to-eye system, a hand-eye calibration method was proposed in this paper.After getting the point coordinate in the camera coordinate frame by using P3P position measurement, the position and orientation relationships between robot space coordinate system and hand-eye coordinate system were established; the concrete steps of hand-eye system calibration were given, the calibration equations and solving method based on least squarewere built. Considered the calculation and measurement error leading to the orthogonal rotation matrix, a simple correction algorithm was used to amend the problem. The calibration method does not need complex auxiliary devices and theprocess is very simple, related simulation results show higher precision and efficiency of the method.
To the micro-assembly robot hand-to-eye system, a hand-eye calibration method was proposed in this paper.After getting the point coordinate in the camera coordinate frame by using P3P position measurement, the position and orientation relationships between robot space coordinate system and hand-eye coordinate system were established; the concrete steps of hand-eye system calibration were given, the calibration equations and solving method based on least squarewere built. Considered the calculation and measurement error leading to the orthogonal rotation matrix, a simple correction algorithm was used to amend the problem. The calibration method does not need complex auxiliary devices and theprocess is very simple, related simulation results show higher precision and efficiency of the method.
2013, 32(5): 766-770,765.
Abstract:
The first natural frequency of rear door is found too close to the excited frequencies of the engine andpavement in the model analysis of a SUV's rear door. Resonance will be produced in daily driving under the circumstances, and the NVH of the rear door will be weakened. In order to conquer the problem, the thickness ofsome components which have higher sensibility on rear door's first natural frequency and weight is treated as the design variables. Trial sample is got through the experiment design method of optimal Latin hypercube and the multidisciplinary approximate models are established by using the response surface method. The surrogate model is thenoptimized by sequential quadratic programming. As a result, the first natural frequency of the rear door is obviouslyimproved in such conditions that the weight of the rear door don't increase.
The first natural frequency of rear door is found too close to the excited frequencies of the engine andpavement in the model analysis of a SUV's rear door. Resonance will be produced in daily driving under the circumstances, and the NVH of the rear door will be weakened. In order to conquer the problem, the thickness ofsome components which have higher sensibility on rear door's first natural frequency and weight is treated as the design variables. Trial sample is got through the experiment design method of optimal Latin hypercube and the multidisciplinary approximate models are established by using the response surface method. The surrogate model is thenoptimized by sequential quadratic programming. As a result, the first natural frequency of the rear door is obviouslyimproved in such conditions that the weight of the rear door don't increase.
2013, 32(5): 771-774,780.
Abstract:
The present objectives are to further reduce the noise of the prototype of electric motor-vane pump andincrease the efficiency. The finite element method (FEM) calculating the stress-strain of some parts and flow fieldand some structure improvement measures of the first prototype were put forward in this paper. The performancetests of the improved prototype have been performed to attain the variety regulations of rotor speed, noise, powerand efficiency with the outlet pressure. The experimental results of the improved prototype were compared withthose of the motor-pump combination with the same power. The results show that the problem of larger internal leakage was solved effectively and the cavitation caused by the narrow internal channels was eliminated in the improvedprototype. The volumetric efficiency is compared to the motor-pump combinations. At the output pressure above13 MPa, the efficiency decreases by about 2% and the noise level decreases by above 11 dB.
The present objectives are to further reduce the noise of the prototype of electric motor-vane pump andincrease the efficiency. The finite element method (FEM) calculating the stress-strain of some parts and flow fieldand some structure improvement measures of the first prototype were put forward in this paper. The performancetests of the improved prototype have been performed to attain the variety regulations of rotor speed, noise, powerand efficiency with the outlet pressure. The experimental results of the improved prototype were compared withthose of the motor-pump combination with the same power. The results show that the problem of larger internal leakage was solved effectively and the cavitation caused by the narrow internal channels was eliminated in the improvedprototype. The volumetric efficiency is compared to the motor-pump combinations. At the output pressure above13 MPa, the efficiency decreases by about 2% and the noise level decreases by above 11 dB.
2013, 32(5): 775-780.
Abstract:
Due to the shortcoming of the LQG(Linear Quadratic Gaussian) when defining the weight matrices, amethod using the genetic algorithm is designed to optimize the LQG controller. This method utilizes the global optimization algorithm of the genetic algorithm to optimize and design the weight matrices with the target function ofchassis performance indexes. This method aims at improving the design efficiency and control performance of theLQG controller. And then a simulation experiment is provided for the active vehicle chassis control. The resultshows that the performance of the actively controlled vehicle chassis using LQG controller optimized by the geneticalgorithm such as the vertical acceleration of seat, the dynamic displacement of the seat suspension and the tire canbe greatly improved, compared to the seat chassis controlled by the normal LQG and the passive one,. Meanwhile,the problem of defining the weight matrices is greatly solved based on the advantage of the normal LQG is sufficiently utilized.
Due to the shortcoming of the LQG(Linear Quadratic Gaussian) when defining the weight matrices, amethod using the genetic algorithm is designed to optimize the LQG controller. This method utilizes the global optimization algorithm of the genetic algorithm to optimize and design the weight matrices with the target function ofchassis performance indexes. This method aims at improving the design efficiency and control performance of theLQG controller. And then a simulation experiment is provided for the active vehicle chassis control. The resultshows that the performance of the actively controlled vehicle chassis using LQG controller optimized by the geneticalgorithm such as the vertical acceleration of seat, the dynamic displacement of the seat suspension and the tire canbe greatly improved, compared to the seat chassis controlled by the normal LQG and the passive one,. Meanwhile,the problem of defining the weight matrices is greatly solved based on the advantage of the normal LQG is sufficiently utilized.
