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RSS2012 Vol. 31, No. 4
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2012, 31(4): 517-522.
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Abstract:
To improve tooth pair meshing quality,we propose a method for determining the parameters for gear shape modification,which takes the housing stiffness into consideration.We establish the simplification algorithm for calculating gear shaft bending and torsional stiffness so as to determine the initial values of parameters of the longitudinal gear shape modification.We use the ANSYS to establish the finite element model for analyzing the contact of gears with a shaft.Using the finite element model,we simulate the gear meshing stiffness and determine the initial values of the parameters of involute modification and longitudinal modification without considering housing stiffness.Finally we propose our simplification algorithm for extracting the housing stiffness matrix,which is then coupled with the gear shaft,thus optimizing the gear shape modification parameters coupled with housing stiffness.The simulation results show that our method can greatly improve the load distribution on tooth surface,indicating that our method is effective.
To improve tooth pair meshing quality,we propose a method for determining the parameters for gear shape modification,which takes the housing stiffness into consideration.We establish the simplification algorithm for calculating gear shaft bending and torsional stiffness so as to determine the initial values of parameters of the longitudinal gear shape modification.We use the ANSYS to establish the finite element model for analyzing the contact of gears with a shaft.Using the finite element model,we simulate the gear meshing stiffness and determine the initial values of the parameters of involute modification and longitudinal modification without considering housing stiffness.Finally we propose our simplification algorithm for extracting the housing stiffness matrix,which is then coupled with the gear shaft,thus optimizing the gear shape modification parameters coupled with housing stiffness.The simulation results show that our method can greatly improve the load distribution on tooth surface,indicating that our method is effective.
2012, 31(4): 523-527.
Abstract:
In order to address the shape choice of lithium battery cells for electric vehicle,according to analyzing orderly a series of evaluation index of the performance of lithium battery cell and lithium battery assembly process and lithium battery pack,and firstly AHP（analytic hierarchy process） algorithm is applied to establish the evaluation model,secondly the main factors were determined,finally three lithium battery with common and different shapes were used as an example,and the results show that comparing with prismatic tank-type cells and cylindrical type cells,the prismatic pouch-type cells have a greater advantage which provides a theoretical basis for the shape choice of electric vehicle with lithium battery cell.
In order to address the shape choice of lithium battery cells for electric vehicle,according to analyzing orderly a series of evaluation index of the performance of lithium battery cell and lithium battery assembly process and lithium battery pack,and firstly AHP（analytic hierarchy process） algorithm is applied to establish the evaluation model,secondly the main factors were determined,finally three lithium battery with common and different shapes were used as an example,and the results show that comparing with prismatic tank-type cells and cylindrical type cells,the prismatic pouch-type cells have a greater advantage which provides a theoretical basis for the shape choice of electric vehicle with lithium battery cell.
2012, 31(4): 528-533.
Abstract:
In order to control the reliability of a CNC machine,we propose a function decomposition method that uses function,motion and action（FMA） and compare it with the traditional function decomposition methods.Through decomposing the CNC machine's functions one by one,we identify all its unit actions that make up its machining processes and then explain the relationship between the unit action and the reliability of the whole machine.With the fault tree,we analyze the unit actions so as to identify the root causes of abnormal unit actions and work out the specific measures of reliability control on the basis of the analysis results.The example has shown that our functional decomposition method that uses FMA is effective for reliability analysis.
In order to control the reliability of a CNC machine,we propose a function decomposition method that uses function,motion and action（FMA） and compare it with the traditional function decomposition methods.Through decomposing the CNC machine's functions one by one,we identify all its unit actions that make up its machining processes and then explain the relationship between the unit action and the reliability of the whole machine.With the fault tree,we analyze the unit actions so as to identify the root causes of abnormal unit actions and work out the specific measures of reliability control on the basis of the analysis results.The example has shown that our functional decomposition method that uses FMA is effective for reliability analysis.
2012, 31(4): 534-537.
Abstract:
Motion compensation method for starry image registration is one of the key technologies,which could effectively improve the dim target detection precision in complex background for space surveillance.In this paper,a new method combining with Delaunay triangulation and ICP algorithm is presented for starry images sequences motion compensation.Firstly,this method establishes the clue matrix for several fixed stars in one starry image by Delaunay triangulation.Secondly,this method could get the corresponding relations between the adjacent starry maps by using the ICP registration algorithm.And through the SVD optimal resolution to get the transform relation between the adjacent frames which is the camera motion model.Finally,the bilinear interpolation method is employed to finish the motion compensation.The experimental results show that,this method can effectively realize high precision motion background compensation,and lay the technical foundation for dim small target detection in complex background.
Motion compensation method for starry image registration is one of the key technologies,which could effectively improve the dim target detection precision in complex background for space surveillance.In this paper,a new method combining with Delaunay triangulation and ICP algorithm is presented for starry images sequences motion compensation.Firstly,this method establishes the clue matrix for several fixed stars in one starry image by Delaunay triangulation.Secondly,this method could get the corresponding relations between the adjacent starry maps by using the ICP registration algorithm.And through the SVD optimal resolution to get the transform relation between the adjacent frames which is the camera motion model.Finally,the bilinear interpolation method is employed to finish the motion compensation.The experimental results show that,this method can effectively realize high precision motion background compensation,and lay the technical foundation for dim small target detection in complex background.
2012, 31(4): 538-542.
Abstract:
Based on theories of finite element,multi-body dynamics and fatigue,the fatigue life of a minibus body under the load of B-level pavement is predicted with the material S-N curve,structural unit load stress and bus-body load spectrum,which realize combining simulation among the software of Hypermesh,MSC.Nastran,ADAMS/Car and MSC.Fatigue.The research results can provide technical supports for the design and improvement of the bus-body structure while we don't rely on the prototype of a minibus.In order to accurately simulate the performances of the body and the chassis,the leaf-spring and the body are considered as flexible structures to establish rigid-flexible coupled multi-body dynamic model in this paper,so as to generate much more accurate simulation results.
Based on theories of finite element,multi-body dynamics and fatigue,the fatigue life of a minibus body under the load of B-level pavement is predicted with the material S-N curve,structural unit load stress and bus-body load spectrum,which realize combining simulation among the software of Hypermesh,MSC.Nastran,ADAMS/Car and MSC.Fatigue.The research results can provide technical supports for the design and improvement of the bus-body structure while we don't rely on the prototype of a minibus.In order to accurately simulate the performances of the body and the chassis,the leaf-spring and the body are considered as flexible structures to establish rigid-flexible coupled multi-body dynamic model in this paper,so as to generate much more accurate simulation results.
2012, 31(4): 543-546.
Abstract:
Aiming at the problem of costing much simulation time when researching the firing dynamics of self-propelled gun,the model of self-propelled gun was established in this paper based on multi-body dynamic theory,contact theory and ADAMS software,after researching typically the modeling method of rack system.The simulation tests on hard-road and soft-road conditions were made based on this model.Through hard-road simulation,the parameters of the model could be considered setting properly in this work condition;compared to the model built by commercial software（such as ADAMS Track Vehicle software（ATV））,the CPU time cost by this model is shorter.Throughout soft-road simulation,the rules of force and motion of the model matched the results of theoretical analysis.The model built in this paper could be further used to firing dynamic characters of self-propelled gun.
Aiming at the problem of costing much simulation time when researching the firing dynamics of self-propelled gun,the model of self-propelled gun was established in this paper based on multi-body dynamic theory,contact theory and ADAMS software,after researching typically the modeling method of rack system.The simulation tests on hard-road and soft-road conditions were made based on this model.Through hard-road simulation,the parameters of the model could be considered setting properly in this work condition;compared to the model built by commercial software（such as ADAMS Track Vehicle software（ATV））,the CPU time cost by this model is shorter.Throughout soft-road simulation,the rules of force and motion of the model matched the results of theoretical analysis.The model built in this paper could be further used to firing dynamic characters of self-propelled gun.
2012, 31(4): 547-551.
Abstract:
For the complexity of the structure and the uncertainty of the impact mechanism of the servo actuator of the aircraft's flight control system,the comprehensive judgement for the healthy status of the actuator system can be achieved by using fuzzy mathematics theory.While the traditional way of the fuzzy mathematics' application expresses the relationship between affect factors and the remark assembly statically,the present paper proposes a method of acquiring dynamic membership function to evaluate the healthy status of servo actuator based on the theory of dynamic fuzzy mathematics.And the judgment results are analyzed by using the weighted average method to gives a qualitative estimation for the healthy status of servo actuator.
For the complexity of the structure and the uncertainty of the impact mechanism of the servo actuator of the aircraft's flight control system,the comprehensive judgement for the healthy status of the actuator system can be achieved by using fuzzy mathematics theory.While the traditional way of the fuzzy mathematics' application expresses the relationship between affect factors and the remark assembly statically,the present paper proposes a method of acquiring dynamic membership function to evaluate the healthy status of servo actuator based on the theory of dynamic fuzzy mathematics.And the judgment results are analyzed by using the weighted average method to gives a qualitative estimation for the healthy status of servo actuator.
2012, 31(4): 552-556.
Abstract:
Position and workspace analysis of mechanism is the basics for study and research of mechanism.In this paper,a novel parallel mechanism named 3-UrSR was proposed.It used 2-DOF spherical five-bar mechanism as the compound drive device.The mechanism freedoms was calculated,and the inverse solution of position of the mechanism was analyzed.Using Matlab software eight groups of inverse solution were determined and its figure was dipicted.At last a numerical simulation example of a mechanism with its workspace arithmetic and figure to verify the feasibility and correctness of the inverse solution.
Position and workspace analysis of mechanism is the basics for study and research of mechanism.In this paper,a novel parallel mechanism named 3-UrSR was proposed.It used 2-DOF spherical five-bar mechanism as the compound drive device.The mechanism freedoms was calculated,and the inverse solution of position of the mechanism was analyzed.Using Matlab software eight groups of inverse solution were determined and its figure was dipicted.At last a numerical simulation example of a mechanism with its workspace arithmetic and figure to verify the feasibility and correctness of the inverse solution.
2012, 31(4): 557-561.
Abstract:
Considering the fluid structure interaction（FSI） effect,the free vibration of pipe conveying non-uniform axial flow was studied based on Euler-Bernoulli beam theory and inextensible assumption.In terms of Hamilton's principle for open system,the dynamic control equation of a simply supported pipe conveying fluid which velocity distribution of parabolic profile on the cross section was derived.In the numerical example,the wave propagation method was adopted to calculate the first five natural frequencies of the with simple supports at both ends in three different cases.Comparing the results with that of pipe conveying uniform axial flow,it is found that higher natural frequencies would be obtained when uniform flow assumption was adopted,especially for the first natural frequency.
Considering the fluid structure interaction（FSI） effect,the free vibration of pipe conveying non-uniform axial flow was studied based on Euler-Bernoulli beam theory and inextensible assumption.In terms of Hamilton's principle for open system,the dynamic control equation of a simply supported pipe conveying fluid which velocity distribution of parabolic profile on the cross section was derived.In the numerical example,the wave propagation method was adopted to calculate the first five natural frequencies of the with simple supports at both ends in three different cases.Comparing the results with that of pipe conveying uniform axial flow,it is found that higher natural frequencies would be obtained when uniform flow assumption was adopted,especially for the first natural frequency.
2012, 31(4): 562-567.
Abstract:
The coupling between the generator and active magnetic bearing affects the stable operation of flywheel system in flywheel energy storage system based on active magnetic bearing,and restricts the control system design of active magnetic bearing.According to the structure of the generator,an analytical method is adopted to analyse the magnetic flux density distribution in the airgap region considering the rotor eccentricity,and the expressions of the unbalanced magnetic force and the unbalanced Lorentz force are educed when the flywheel energy storage system is charged or discharged.The dynamics simulation model of electromechanical coupling between the generator and active magnetic bearing is established,and the coupling effects between the unbalanced force brought by generator and the flywheel dynamics performance based on active magnetic bearing are analysed.Based on the analysis,an active magnetic bearing system is designed to restrain the electromechanical coupling.The results indicate that when the generator has a big size and the system is used in high electric-power field,the unbalanced force brought by rotor eccentricity in the generator is large,and have obvious impact on the performance of flywheel dynamics.The active magnetic bearing system can be reasonably designed to restrain the electromechanical coupling.
The coupling between the generator and active magnetic bearing affects the stable operation of flywheel system in flywheel energy storage system based on active magnetic bearing,and restricts the control system design of active magnetic bearing.According to the structure of the generator,an analytical method is adopted to analyse the magnetic flux density distribution in the airgap region considering the rotor eccentricity,and the expressions of the unbalanced magnetic force and the unbalanced Lorentz force are educed when the flywheel energy storage system is charged or discharged.The dynamics simulation model of electromechanical coupling between the generator and active magnetic bearing is established,and the coupling effects between the unbalanced force brought by generator and the flywheel dynamics performance based on active magnetic bearing are analysed.Based on the analysis,an active magnetic bearing system is designed to restrain the electromechanical coupling.The results indicate that when the generator has a big size and the system is used in high electric-power field,the unbalanced force brought by rotor eccentricity in the generator is large,and have obvious impact on the performance of flywheel dynamics.The active magnetic bearing system can be reasonably designed to restrain the electromechanical coupling.
2012, 31(4): 568-571.
Abstract:
According to the existing multi-frame optoelectronic pod vibration isolation system,a new type of inner and outer shock absorber which could limit angular displacement in different side of the pod was designed.Through the rational combination of the inner and outer shock absorbers which was put in or out of the pot,the angular constraints and rotational degrees of freedom and classified attenuation of the pod could be achieved,and the range of stiffness and damping of the shock absorbers were calculated.The three-dimensional model of the shock absorbers and the simplified pod were built by Solidworks then the vibration reduction performance of the system was simulated by Adams/Vibration.The results show that the proposed new type of inner and outer shock absorbers can meet the requirement of non-angular displacement vibration suppression when they were put in the right position.
According to the existing multi-frame optoelectronic pod vibration isolation system,a new type of inner and outer shock absorber which could limit angular displacement in different side of the pod was designed.Through the rational combination of the inner and outer shock absorbers which was put in or out of the pot,the angular constraints and rotational degrees of freedom and classified attenuation of the pod could be achieved,and the range of stiffness and damping of the shock absorbers were calculated.The three-dimensional model of the shock absorbers and the simplified pod were built by Solidworks then the vibration reduction performance of the system was simulated by Adams/Vibration.The results show that the proposed new type of inner and outer shock absorbers can meet the requirement of non-angular displacement vibration suppression when they were put in the right position.
2012, 31(4): 572-577.
Abstract:
Taking the electric vehicle designed by Sun Yat-sen University as the research object,the vehicle's braking force is analyzed.On the premise of keeping the vehicle's driving stability,with consideration of vehicle's traction motor and battery pack,the maximum recycle of the braking energy is realized.A new braking model is promoted and integrated with the ADVISOR.The simulation shows that the vehicle's regenerative braking efficiency is greatly improved by adopting the optimized regenerative braking strategy.
Taking the electric vehicle designed by Sun Yat-sen University as the research object,the vehicle's braking force is analyzed.On the premise of keeping the vehicle's driving stability,with consideration of vehicle's traction motor and battery pack,the maximum recycle of the braking energy is realized.A new braking model is promoted and integrated with the ADVISOR.The simulation shows that the vehicle's regenerative braking efficiency is greatly improved by adopting the optimized regenerative braking strategy.
2012, 31(4): 578-582.
Abstract:
The variable displacement mechanism with displacement-force-feedback is a typical closed-loop position control system of valve controlled cylinder.According to the composition and operating principle of this variable displacement mechanism,the mathematical model of the control system is built based on linearization theory,and the exactness of the model is demonstrated by using hydraulic test rig.Besides,the proportional characteristic and influence factors of control system are analyzed.The research results show that the central offset spring of pilot valve has an important impact on the proportional characteristic of the control system,and the proportional coefficient of control system is decreased with the increasing of stiffness coefficient of offset spring,while the closure interval of control system is increased with the increasing of pre-packing force of offset spring.
The variable displacement mechanism with displacement-force-feedback is a typical closed-loop position control system of valve controlled cylinder.According to the composition and operating principle of this variable displacement mechanism,the mathematical model of the control system is built based on linearization theory,and the exactness of the model is demonstrated by using hydraulic test rig.Besides,the proportional characteristic and influence factors of control system are analyzed.The research results show that the central offset spring of pilot valve has an important impact on the proportional characteristic of the control system,and the proportional coefficient of control system is decreased with the increasing of stiffness coefficient of offset spring,while the closure interval of control system is increased with the increasing of pre-packing force of offset spring.
2012, 31(4): 583-587.
Abstract:
In order to reuse the 3D CAD model,a new method of 3D CAD model retrieval based on feature adjancent graph is proposed.First,a representation of feature adjancent graph（FAG） for the CAD model is extracted by automatic identification-based and interactive identification-assisted.Next,the vertex product graph of two CAD model's FAGS is constructed,and then the ant colony algorithm is employed to detect maximum-cliques in the vertex product graph.At last,the similarity of models is calculated by comparing the maximum-cliques.Experimental results show that this method can realize the 3D CAD model retrieval and its efficiency meets the requirements of applications.
In order to reuse the 3D CAD model,a new method of 3D CAD model retrieval based on feature adjancent graph is proposed.First,a representation of feature adjancent graph（FAG） for the CAD model is extracted by automatic identification-based and interactive identification-assisted.Next,the vertex product graph of two CAD model's FAGS is constructed,and then the ant colony algorithm is employed to detect maximum-cliques in the vertex product graph.At last,the similarity of models is calculated by comparing the maximum-cliques.Experimental results show that this method can realize the 3D CAD model retrieval and its efficiency meets the requirements of applications.
2012, 31(4): 588-591.
Abstract:
Based on the finite element method,the stability problem was studied for the composite honeycomb plate with a scarf repair.Using commercial finite element analysis software MSC.Patran/Nastran and the equivalent method of honeycomb core,a three-dimensional finite element model is established for the composite honeycomb plate with a scarf repair.Furthermore,the influence of the scarf angles and adhesive thickness on the buckling eigenvalues is calculated through the numerical examples and fitting method.
Based on the finite element method,the stability problem was studied for the composite honeycomb plate with a scarf repair.Using commercial finite element analysis software MSC.Patran/Nastran and the equivalent method of honeycomb core,a three-dimensional finite element model is established for the composite honeycomb plate with a scarf repair.Furthermore,the influence of the scarf angles and adhesive thickness on the buckling eigenvalues is calculated through the numerical examples and fitting method.
2012, 31(4): 592-596.
Abstract:
In this paper,the locally weakened columns' buckling load and failure pattern were discussed with finite element method（FEM）.Firstly,the linear buckling with small weakening was analyzed and then the nonlinear buckling with large weakening was emphasized.Finally integral curves,which present the relationship between weakening and buckling load,were carried out together with discussions of some other parameters such as flexibility and the level of weakening.The results showed that the effect of weakening on the linear buckling could be ignored,while it was significant on nonlinear buckling.The critical load was obviously reduced in nonlinear buckling,hence the weakening could not be ignored.The nonlinear buckling was sensitive to the weakened location while linear buckling was little affected by the location.The buckling load kept decreasing when the number of the weakening incerased of both linear and nonlinear buckling.
In this paper,the locally weakened columns' buckling load and failure pattern were discussed with finite element method（FEM）.Firstly,the linear buckling with small weakening was analyzed and then the nonlinear buckling with large weakening was emphasized.Finally integral curves,which present the relationship between weakening and buckling load,were carried out together with discussions of some other parameters such as flexibility and the level of weakening.The results showed that the effect of weakening on the linear buckling could be ignored,while it was significant on nonlinear buckling.The critical load was obviously reduced in nonlinear buckling,hence the weakening could not be ignored.The nonlinear buckling was sensitive to the weakened location while linear buckling was little affected by the location.The buckling load kept decreasing when the number of the weakening incerased of both linear and nonlinear buckling.
2012, 31(4): 597-599.
Abstract:
As a new plastic processing technology,the incremental forming has a more complicated frictional mechanism than other technologies.Through treating the surfaces of steel sheet and tool respectively,we study the frictional mechanism and lubrication technology for the incremental forming of 0Cr18Ni9 stainless steel sheet.We use the physical vapor deposition（PVD） technique to put the high hardness and good wear resistance TiAlN coating on the high speed steel forming tool;we carry out the oxalate treatment of the stainless steel sheet to form an oxalic acidated film as the lubrication carrier.The experimental results show that the stainless steel sheet and tool whose surfaces are treated with our technology have smooth surfaces,with their surface roughness Ra reaching 0.94 μm and the tool thus formed having no wear.
As a new plastic processing technology,the incremental forming has a more complicated frictional mechanism than other technologies.Through treating the surfaces of steel sheet and tool respectively,we study the frictional mechanism and lubrication technology for the incremental forming of 0Cr18Ni9 stainless steel sheet.We use the physical vapor deposition（PVD） technique to put the high hardness and good wear resistance TiAlN coating on the high speed steel forming tool;we carry out the oxalate treatment of the stainless steel sheet to form an oxalic acidated film as the lubrication carrier.The experimental results show that the stainless steel sheet and tool whose surfaces are treated with our technology have smooth surfaces,with their surface roughness Ra reaching 0.94 μm and the tool thus formed having no wear.
2012, 31(4): 600-603.
Abstract:
In order to investigate the effects of grease lubrication on fretting wear of ball bearings,a series of fretting wear tests were performed under the dry condition and grease lubrication using a home-made fretting wear test rig.The results show that the grease lubrication can effectively reduce fretting wear of ball bearings;Reduction effects on wear increase as the oscillation amplitude increases;compared with dry condition,the fretting wear under grease lubrication always keeps little as the number of cycles increases.The observations of worn surface morphologies of outer ring reveal that oxidation on wear surface decreases under grease lubrication,but the probability of fatigue crack initiation increases at the later stage of fretting.
In order to investigate the effects of grease lubrication on fretting wear of ball bearings,a series of fretting wear tests were performed under the dry condition and grease lubrication using a home-made fretting wear test rig.The results show that the grease lubrication can effectively reduce fretting wear of ball bearings;Reduction effects on wear increase as the oscillation amplitude increases;compared with dry condition,the fretting wear under grease lubrication always keeps little as the number of cycles increases.The observations of worn surface morphologies of outer ring reveal that oxidation on wear surface decreases under grease lubrication,but the probability of fatigue crack initiation increases at the later stage of fretting.
2012, 31(4): 604-608.
Abstract:
In order to accurately and quickly assess the positioning accuracy of a heavy-duty CNC lathe and carry out its comprehensive analysis,we study a certain heavy-duty CNC lathe.First,we study the principles of laser measurement of its positioning accuracy.Then we select the three-section displacement in the Z axis direction.According to China's standards,we determine seven goal position points for each section of displacement and measure the positioning accuracy of three sections with the laser interferometer,thus obtaining the position accuracy of goal position points.We fit the measured data of one of the sections with sixth order polynomial and select many equidistant nodes along the fitting curve.Finally we propose our method for predicting the positioning accuracy along the Z-axle direction of the heavy-duty CNC lathe,which is based on the full-domain data BP neural network and RBF neural network.The comparison of the measured results indicates that the prediction based on the two neural networks is feasible and effective.
In order to accurately and quickly assess the positioning accuracy of a heavy-duty CNC lathe and carry out its comprehensive analysis,we study a certain heavy-duty CNC lathe.First,we study the principles of laser measurement of its positioning accuracy.Then we select the three-section displacement in the Z axis direction.According to China's standards,we determine seven goal position points for each section of displacement and measure the positioning accuracy of three sections with the laser interferometer,thus obtaining the position accuracy of goal position points.We fit the measured data of one of the sections with sixth order polynomial and select many equidistant nodes along the fitting curve.Finally we propose our method for predicting the positioning accuracy along the Z-axle direction of the heavy-duty CNC lathe,which is based on the full-domain data BP neural network and RBF neural network.The comparison of the measured results indicates that the prediction based on the two neural networks is feasible and effective.
2012, 31(4): 609-611.
Abstract:
The planar linkage mechanism with error of bar length is studied.According to geometrical theory of reliability index,a kinematics accuracy reliability index computation method of mechanism is presented on the basis of improved particle swarm optimization.Simulations results on kinematics accuracy reliability index of mechanism demonstrate that the proposed method is effective and practical,and provides an effective approach to calculate the kinematics accuracy reliability index.
The planar linkage mechanism with error of bar length is studied.According to geometrical theory of reliability index,a kinematics accuracy reliability index computation method of mechanism is presented on the basis of improved particle swarm optimization.Simulations results on kinematics accuracy reliability index of mechanism demonstrate that the proposed method is effective and practical,and provides an effective approach to calculate the kinematics accuracy reliability index.
2012, 31(4): 612-615.
Abstract:
Using a cylindrical roller bearing as original object model,we propose a simulation method for forecasting the radial jump of its outer ring.Under the condition that there exist known roundness errors in the outer ring roll path,we use the C++ program to work out a simulation algorithm for forecasting the radial jump of the outer ring and verify the correctness of the simulation algorithm.The simulation produces the curves for the radial jump of the outer ring of the cylindrical roller bearing.Then we analyze the relationship between the radial jump of the outer ring and the number of orders of harmonic wave of the roundness error in the outer ring roll path and the relationship between the radial jump of the outer ring and the coefficients of the harmonic wave of roundness error.
Using a cylindrical roller bearing as original object model,we propose a simulation method for forecasting the radial jump of its outer ring.Under the condition that there exist known roundness errors in the outer ring roll path,we use the C++ program to work out a simulation algorithm for forecasting the radial jump of the outer ring and verify the correctness of the simulation algorithm.The simulation produces the curves for the radial jump of the outer ring of the cylindrical roller bearing.Then we analyze the relationship between the radial jump of the outer ring and the number of orders of harmonic wave of the roundness error in the outer ring roll path and the relationship between the radial jump of the outer ring and the coefficients of the harmonic wave of roundness error.
2012, 31(4): 616-621.
Abstract:
A strain monitoring technique for hydraulic system based on resistance strain gauge is developed though theoretical and experimental studies.By analyzing the extracted monitoring signals,it is concluded that in the design of hydraulic piping system,the number of bend should be minimized or the radius should be increased.And the principle of how to select the detection bridge and the strain monitoring signals is also presented.The application example shows that the strain monitoring technique is suitable to the online monitoring and analysis for hydraulic systems.
A strain monitoring technique for hydraulic system based on resistance strain gauge is developed though theoretical and experimental studies.By analyzing the extracted monitoring signals,it is concluded that in the design of hydraulic piping system,the number of bend should be minimized or the radius should be increased.And the principle of how to select the detection bridge and the strain monitoring signals is also presented.The application example shows that the strain monitoring technique is suitable to the online monitoring and analysis for hydraulic systems.
2012, 31(4): 622-626.
Abstract:
Using stochastic finite element method（SFEM）,we deal with the random variables for structural analysis and set up the safe margin of the beam and plate structure.With the branch and boundary method,we find its main failure modes,calculate its reliability index and analyze its sensitivity.Then,we develop the optimization model for beam and plate structure,using the minimum weight as the objective function and the constraints that the reliability index should be larger than the set value and that the design variables should satisfy certain conditions.We jointly use the neural network and the genetic algorithm to solve the optimization model.We use the SFEM to establish a random structural optimization and design method that is based on the reliability theory.We use the method to calculate and optimize the beams and plates of a ship cabin.The calculation results show that our method is effective for the reliability optimization of structures with multiple random factors and takes time 60% less than before,thus being very efficient.
Using stochastic finite element method（SFEM）,we deal with the random variables for structural analysis and set up the safe margin of the beam and plate structure.With the branch and boundary method,we find its main failure modes,calculate its reliability index and analyze its sensitivity.Then,we develop the optimization model for beam and plate structure,using the minimum weight as the objective function and the constraints that the reliability index should be larger than the set value and that the design variables should satisfy certain conditions.We jointly use the neural network and the genetic algorithm to solve the optimization model.We use the SFEM to establish a random structural optimization and design method that is based on the reliability theory.We use the method to calculate and optimize the beams and plates of a ship cabin.The calculation results show that our method is effective for the reliability optimization of structures with multiple random factors and takes time 60% less than before,thus being very efficient.
2012, 31(4): 627-632.
Abstract:
To develop an underwater propulsor with high maneuverability and stability for the purpose of search and rescue,environment monitoring,resource detecting and military reconnoitering etc,as well as considering the badly effect on aquatic organism by modern screw propeller,the bluespotted ray was selected as bionic object upon extensive investigations and analysis on various fishes.Through principle of biomimetic engineering,a high performance biomimetic bluespotted ray model was developed.Firstly,we presented a brief introduction to the live bluespotted ray.Then,a detailed analysis on mechanical design principles and methods was conducted.Finally,a coordinate system was established to determine the kinematic and hydrodynamic equations of both oscillating fin ray and undulating fin.These works provide a theoretical basis for developing a high performance underwater propulsor.The initial experimental results illustrated that： the biomimetic bluespotted ray were able to achieve no-radius turning,its body could hold a stable posture during cruising and disturb surrounding fluid less.
To develop an underwater propulsor with high maneuverability and stability for the purpose of search and rescue,environment monitoring,resource detecting and military reconnoitering etc,as well as considering the badly effect on aquatic organism by modern screw propeller,the bluespotted ray was selected as bionic object upon extensive investigations and analysis on various fishes.Through principle of biomimetic engineering,a high performance biomimetic bluespotted ray model was developed.Firstly,we presented a brief introduction to the live bluespotted ray.Then,a detailed analysis on mechanical design principles and methods was conducted.Finally,a coordinate system was established to determine the kinematic and hydrodynamic equations of both oscillating fin ray and undulating fin.These works provide a theoretical basis for developing a high performance underwater propulsor.The initial experimental results illustrated that： the biomimetic bluespotted ray were able to achieve no-radius turning,its body could hold a stable posture during cruising and disturb surrounding fluid less.
2012, 31(4): 633-638.
Abstract:
According to the NC grinding mechanism of the spiral bevel gear and the Gleason contact principle,we obtain the mathematical model of grinding physical parameters that influence the grinding residual stress of a spiral bevel gear.We establish the 3D finite element model of the spiral bevel gear;on this basis,we obtain its physical fields such as temperature field and stress field by applying the thermo-elastic-plastic theory and the numerical finite element method.We simulate and analyze the grinding residual stress by doing the coupled computation of the two physical fields.The simulation results show that：（1） the grinding tooth surface of the spiral bevel gear has compressive residual stress;the inside tooth has tensile residual stress;（2） the size of grinding residual stress varies with the varying grinding conditions;the grinding residual stress decreases with decreasing grinding depth and speed of grinding wheel,while increasing with decreasing extended speed;the grinding residual stress is greater in the dry grinding condition than in the wet grinding condition.Finally,the experimental results show that the finite element analysis of grinding residual stresses is effective.
According to the NC grinding mechanism of the spiral bevel gear and the Gleason contact principle,we obtain the mathematical model of grinding physical parameters that influence the grinding residual stress of a spiral bevel gear.We establish the 3D finite element model of the spiral bevel gear;on this basis,we obtain its physical fields such as temperature field and stress field by applying the thermo-elastic-plastic theory and the numerical finite element method.We simulate and analyze the grinding residual stress by doing the coupled computation of the two physical fields.The simulation results show that：（1） the grinding tooth surface of the spiral bevel gear has compressive residual stress;the inside tooth has tensile residual stress;（2） the size of grinding residual stress varies with the varying grinding conditions;the grinding residual stress decreases with decreasing grinding depth and speed of grinding wheel,while increasing with decreasing extended speed;the grinding residual stress is greater in the dry grinding condition than in the wet grinding condition.Finally,the experimental results show that the finite element analysis of grinding residual stresses is effective.
2012, 31(4): 639-642,647.
Abstract:
Aircraft structure is often in the dynamic loading environments due to sudden wind,maneuver,and so on,that may lead to fatigue failure and serious accidents.Based on the Dirlik fatigue life prediction method,combining with structural damage calculation and modal analysis,this study investigates the mechanisms of vibration fatigue failure by taking a typical thin-walled structure when it is in a special load environment which can provoke the fundamental frequency mode and a higher order mode.It is shown that the sharp reduction in fatigue life is due to the combination of the resonance mode together with high modes with some special characteristics.
Aircraft structure is often in the dynamic loading environments due to sudden wind,maneuver,and so on,that may lead to fatigue failure and serious accidents.Based on the Dirlik fatigue life prediction method,combining with structural damage calculation and modal analysis,this study investigates the mechanisms of vibration fatigue failure by taking a typical thin-walled structure when it is in a special load environment which can provoke the fundamental frequency mode and a higher order mode.It is shown that the sharp reduction in fatigue life is due to the combination of the resonance mode together with high modes with some special characteristics.
2012, 31(4): 643-647.
Abstract:
The rotor blade and disk in the fan and compressor of aero-engine is subjected with combined high and low cycle loading.In order to ascertain the effects of the combined cycle situation on the fatigue crack propagation,the combined cycle fatigue（CCF）,and low cycle fatigue（LCF） of TC11 titanium alloy have been carried out respectively.When ΔK（HCF）ΔKth,the combined loading accelerates crack growth.Scanning electron microscope is used to observe fractography.Fatigue fringe of LCF fracture surface is clearer and secondary cracks is deep,the direction and distribution of secondary cracks is messy.CCF fracture surface has the characteristics that obvious secondary cracks and small fatigue fringe are approximately equably distributed.For a given HCF ΔK,ΔKtotal in CCF is greater and crack opening is bigger.During the crack propagation under CCF loading,dimples and cleavage are clearer.
The rotor blade and disk in the fan and compressor of aero-engine is subjected with combined high and low cycle loading.In order to ascertain the effects of the combined cycle situation on the fatigue crack propagation,the combined cycle fatigue（CCF）,and low cycle fatigue（LCF） of TC11 titanium alloy have been carried out respectively.When ΔK（HCF）ΔKth,the combined loading accelerates crack growth.Scanning electron microscope is used to observe fractography.Fatigue fringe of LCF fracture surface is clearer and secondary cracks is deep,the direction and distribution of secondary cracks is messy.CCF fracture surface has the characteristics that obvious secondary cracks and small fatigue fringe are approximately equably distributed.For a given HCF ΔK,ΔKtotal in CCF is greater and crack opening is bigger.During the crack propagation under CCF loading,dimples and cleavage are clearer.
2012, 31(4): 648-651,655.
Abstract:
In order to improve the stability of the rack area and the efficiency of incoming and outgoing of the articles to be stored in a warehouse,we propose the decision-making model that is based on the theory of polychromatic sets and the particle swarm algorithm.We use the theory of polychromatic sets to zone the rack area and the particle swarm algorithm to allocate the space for articles.We dealt with the diversity of particles during their iteration,thus avoiding the local optimum.An example shows that the method based on our model can reduce the time taken for the incoming of articles without sacrificing the stability of the rack area.Compared with traditional methods and genetic algorithm,this method has great advantages and optimizes the allocation of space for articles.
In order to improve the stability of the rack area and the efficiency of incoming and outgoing of the articles to be stored in a warehouse,we propose the decision-making model that is based on the theory of polychromatic sets and the particle swarm algorithm.We use the theory of polychromatic sets to zone the rack area and the particle swarm algorithm to allocate the space for articles.We dealt with the diversity of particles during their iteration,thus avoiding the local optimum.An example shows that the method based on our model can reduce the time taken for the incoming of articles without sacrificing the stability of the rack area.Compared with traditional methods and genetic algorithm,this method has great advantages and optimizes the allocation of space for articles.
2012, 31(4): 652-655.
Abstract:
Based on the rotor dynamics theory,the dynamic model of crankshaft is build based on the continuous distributional ladder beam model to study the relationship between dynamic unbalance and vibration of crankshaft in drilling pump,and their relational expression is derived.The result shows that the total unbalance of crankshaft can be determined as long as the vibration amplitudes of bearing are measured.And it provides theoretical basis for setting up balance weight at crankshaft to control the vibration of drilling pump.
Based on the rotor dynamics theory,the dynamic model of crankshaft is build based on the continuous distributional ladder beam model to study the relationship between dynamic unbalance and vibration of crankshaft in drilling pump,and their relational expression is derived.The result shows that the total unbalance of crankshaft can be determined as long as the vibration amplitudes of bearing are measured.And it provides theoretical basis for setting up balance weight at crankshaft to control the vibration of drilling pump.
2012, 31(4): 656-659,663.
Abstract:
The noise of intake system is a major sound source for diesel engines,this problem is effectively solved in this paper by the way of designing intake muffler.First,based on spectrum analysis of inlet noise signal of diesel engine,the noise frequencies that need to be improved were indentified.Then combining the transfer matrix method with the finite element analysis,the muffler with resonance structure was designed;its vibration characteristics was obtained and optimized based on the modal analysis technique.Finally,the experimental results show that the inlet noise is suitably reduced;and the surface radiation noise is lower than the inlet noise.Therefore the muffler designed in this paper could meet the requirements for reducing noise of the intake system.
The noise of intake system is a major sound source for diesel engines,this problem is effectively solved in this paper by the way of designing intake muffler.First,based on spectrum analysis of inlet noise signal of diesel engine,the noise frequencies that need to be improved were indentified.Then combining the transfer matrix method with the finite element analysis,the muffler with resonance structure was designed;its vibration characteristics was obtained and optimized based on the modal analysis technique.Finally,the experimental results show that the inlet noise is suitably reduced;and the surface radiation noise is lower than the inlet noise.Therefore the muffler designed in this paper could meet the requirements for reducing noise of the intake system.
2012, 31(4): 660-663.
Abstract:
For the complexity of parallel robot's workspace,using screw theory to analyze the degrees of freedom of the 3-PRS parallel robot.It is known that there are three degrees of freedom including the rotation around the x-axis and y-axis and movement along the z-axis with the kinematical platform of the mechanism.According to the above matter,the mathematical model of the workspace is described by means of the close relationship between the mechanical vectors.Research and simulation are done by making use of Matlab software,and then the workspace of the 3-PRS parallel robot is obtained,which is symmetric and the internal cavity is not found.This method is also applicable to research the workspace and motion analysis of other parallel robots.
For the complexity of parallel robot's workspace,using screw theory to analyze the degrees of freedom of the 3-PRS parallel robot.It is known that there are three degrees of freedom including the rotation around the x-axis and y-axis and movement along the z-axis with the kinematical platform of the mechanism.According to the above matter,the mathematical model of the workspace is described by means of the close relationship between the mechanical vectors.Research and simulation are done by making use of Matlab software,and then the workspace of the 3-PRS parallel robot is obtained,which is symmetric and the internal cavity is not found.This method is also applicable to research the workspace and motion analysis of other parallel robots.
2012, 31(4): 664-668,673.
Abstract:
With the failure data of equipment or parts,the reliability prediction is studied by using Weibull probability and statistical analysis method.First,the scattered condition of failure data is analyzed based on the Weibull probability plot to judge the single Weibull or mixed Weibull model must be established.Secondly,the parameters of model are estimated： for the single Weibull model,the least-squares method of y on x to minimize the sum of squares of the vertical residuals and the least-squares method of x on y minimize the sum of squares of the horizontal residuals are presented to give the selected basis of them;for the mixed Weibull model,the expectation maximization（namely EM） algorithms of repeated iteration to convergence is presented.Finally,the two groups of failure data are applied to show that the model selection principles and the parameter estimation are feasible and effective,and the reliability prediction of equipment is achievable.
With the failure data of equipment or parts,the reliability prediction is studied by using Weibull probability and statistical analysis method.First,the scattered condition of failure data is analyzed based on the Weibull probability plot to judge the single Weibull or mixed Weibull model must be established.Secondly,the parameters of model are estimated： for the single Weibull model,the least-squares method of y on x to minimize the sum of squares of the vertical residuals and the least-squares method of x on y minimize the sum of squares of the horizontal residuals are presented to give the selected basis of them;for the mixed Weibull model,the expectation maximization（namely EM） algorithms of repeated iteration to convergence is presented.Finally,the two groups of failure data are applied to show that the model selection principles and the parameter estimation are feasible and effective,and the reliability prediction of equipment is achievable.
2012, 31(4): 669-673.
Abstract:
In this paper,the vibration frequency adjustment principle of vibration rollers was analyzed,the hydraulic system was designed and its mathematical model was presented for adjusting vibration frequency.In order to ensure that the vibration frequency of vibration rollers can be real-time controlled according to the compaction materials,the control principle of vibration frequency and the genetic algorithm of PID parameters setting and optimization for control system were studied based the model.Then the vibration frequency control system of vibratory rollers was developed and its field test was accomplished.The results show that the response of vibration frequency control system is very quick and its performances are stable,in which the best vibration frequency can be set in control system according to different compacted soils.
In this paper,the vibration frequency adjustment principle of vibration rollers was analyzed,the hydraulic system was designed and its mathematical model was presented for adjusting vibration frequency.In order to ensure that the vibration frequency of vibration rollers can be real-time controlled according to the compaction materials,the control principle of vibration frequency and the genetic algorithm of PID parameters setting and optimization for control system were studied based the model.Then the vibration frequency control system of vibratory rollers was developed and its field test was accomplished.The results show that the response of vibration frequency control system is very quick and its performances are stable,in which the best vibration frequency can be set in control system according to different compacted soils.
2012, 31(4): 674-678,684.
Abstract:
Aiming at the environment of the outdoors,and comparing the advantages of the wheeled walking mechanism and tracked walking mechanism,a wheeled-tracked environment robot was designed,also the changing mechanism design and its realization were expounded.Using UG NX,a model was established.The kinematics model for robot was established by means of the homogeneous coordinate transformation,then both forward and inverse kinematics were solved.To carry out the kinematics simulation,motion simulation module of UG was used.The results showed that it can well finish the task of collecting garbage.
Aiming at the environment of the outdoors,and comparing the advantages of the wheeled walking mechanism and tracked walking mechanism,a wheeled-tracked environment robot was designed,also the changing mechanism design and its realization were expounded.Using UG NX,a model was established.The kinematics model for robot was established by means of the homogeneous coordinate transformation,then both forward and inverse kinematics were solved.To carry out the kinematics simulation,motion simulation module of UG was used.The results showed that it can well finish the task of collecting garbage.
2012, 31(4): 679-684.
Abstract:
In order to obtain the characteristic of flow field around cylinder under small Reynolds number,the evolution process of reverse symmetry eddy in unsteady flow around cylinder was numerically simulated based on finite volume method（FVM）,SIMEPLEC algorithm and laminar flow model under Re=40 by using the computational fluid dynamic（CFD） software Fluent.The multi-block grid technology and structured O type grid was used to generate the calculation region.This paper studies the dimension change and landscape orientation force change of the reverse symmetry eddy in the evolution process.The paper also researches the distribution and variation rules of pressure,velocity,wall shear stress and stream function during the evolution process.Numerical simulation results show that the evolution rule of reverse symmetry eddy is similar to nature biology,namely change is obvious at early period and is steady at late period.The landscape orientation force decreases firstly and then increases and finlly becomes steady.The minimum pressure location on cylinder wall located bearly behind the tangent point,and moves toward the tangent point in the evolution process.The velocity and the wall shear stress both present M type distribution characteristic,and the maximums both appear at about 57.3°.The stream function distribution presents center symmetry character and reaches minimum at about 45.8°.
In order to obtain the characteristic of flow field around cylinder under small Reynolds number,the evolution process of reverse symmetry eddy in unsteady flow around cylinder was numerically simulated based on finite volume method（FVM）,SIMEPLEC algorithm and laminar flow model under Re=40 by using the computational fluid dynamic（CFD） software Fluent.The multi-block grid technology and structured O type grid was used to generate the calculation region.This paper studies the dimension change and landscape orientation force change of the reverse symmetry eddy in the evolution process.The paper also researches the distribution and variation rules of pressure,velocity,wall shear stress and stream function during the evolution process.Numerical simulation results show that the evolution rule of reverse symmetry eddy is similar to nature biology,namely change is obvious at early period and is steady at late period.The landscape orientation force decreases firstly and then increases and finlly becomes steady.The minimum pressure location on cylinder wall located bearly behind the tangent point,and moves toward the tangent point in the evolution process.The velocity and the wall shear stress both present M type distribution characteristic,and the maximums both appear at about 57.3°.The stream function distribution presents center symmetry character and reaches minimum at about 45.8°.
2012, 31(4): 685-688.
Abstract:
The PZT material was selected in this paper to control the vibration of flexible manipulator.The inverse piezoelectric effects of the PZT material and the principle of suppressing vibration were introduced.PZT actuators and joint control torque were respectively used to control vibration and rotary motion of flexible manipulator.The flexible manipulator was controlled to achieve the desired position in limited time by joint control torque and manipulator's vibration was actively controlled by PZT actuators during motion.The dynamic equations of flexible manipulator system were established.PZT actuators control strategy and joint control torque were designed.The numerical simulation results proved the method of the designed PZT actuator control strategy and joint control torque was effective.
The PZT material was selected in this paper to control the vibration of flexible manipulator.The inverse piezoelectric effects of the PZT material and the principle of suppressing vibration were introduced.PZT actuators and joint control torque were respectively used to control vibration and rotary motion of flexible manipulator.The flexible manipulator was controlled to achieve the desired position in limited time by joint control torque and manipulator's vibration was actively controlled by PZT actuators during motion.The dynamic equations of flexible manipulator system were established.PZT actuators control strategy and joint control torque were designed.The numerical simulation results proved the method of the designed PZT actuator control strategy and joint control torque was effective.
