2000 Vol.13(3)
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2000, 14(3).
Abstract:
The deformation of reeds in automotive hydraulic shock absorbers is analyzed with the finite element method.Combination of different thick reeds mounted on different supports is studied.The computational tesults show the deformation of the overlapped reeds is not always equal to the sum of defoection of single reed under any conditionS.Experimental results prove computational results to be correct and computational method effective.The method of analysis and view of point can provide reference to the design and manufacture of hydraulic shock absorbers using reeds.
The deformation of reeds in automotive hydraulic shock absorbers is analyzed with the finite element method.Combination of different thick reeds mounted on different supports is studied.The computational tesults show the deformation of the overlapped reeds is not always equal to the sum of defoection of single reed under any conditionS.Experimental results prove computational results to be correct and computational method effective.The method of analysis and view of point can provide reference to the design and manufacture of hydraulic shock absorbers using reeds.
2000, 14(3).
Abstract:
The front steering angle control and its integration with the direct yaw moment control are suggested to enhance the handling performance for heavy-duty vehicles based on a 3D vehicle model.The double-cost-function LQR methodology(DLQR),which extends the concept and the qpplicable field of LQR to express the practical requirements more plainly,is proposed to determine the control input value:compensation value of front steering angle in the optimal model. A simple auto-tuning proportion controller is employed in direct yaw moment control to regulate the miment timely.The simulation results show that front steering angle control using DLQR has good ability to achieve the desired steering output in the different running conditions. DLQR is more powerful to balance many facyors effectively based on the explicit mathematics expression of the physics of the problem than LQR does.
The front steering angle control and its integration with the direct yaw moment control are suggested to enhance the handling performance for heavy-duty vehicles based on a 3D vehicle model.The double-cost-function LQR methodology(DLQR),which extends the concept and the qpplicable field of LQR to express the practical requirements more plainly,is proposed to determine the control input value:compensation value of front steering angle in the optimal model. A simple auto-tuning proportion controller is employed in direct yaw moment control to regulate the miment timely.The simulation results show that front steering angle control using DLQR has good ability to achieve the desired steering output in the different running conditions. DLQR is more powerful to balance many facyors effectively based on the explicit mathematics expression of the physics of the problem than LQR does.
2000, 14(3).
Abstract:
A novel fullerene-styrene-maleic anhydride copolymer is reported.TEM analyses shows it is water-soluble nanoball of average diameter of about 83 nm.The tribological behavior is evaluated by four-ball machine. It was found that addition of fullerene copolymer to base stock(2% triethanolamine aqueous solution)resulted in a raise in load-carrying ability(F value)from 130 N to maximum 480 N,and a reduction in coefficient of frivtion from 0.235 to minimum 0.063.SEM analyses indicates that the wear scars obtained with fullerene copolymer exhibited mild scratches,while sharp grooving and serious pull-out phenomnon were observed in the presence of base stock without additive.The improvements in friction,wear and load-carrying capacity are probably due to the presence of fullerene copolymer nanoballs,which may act as molecule ball bearings,which in turn lead to elastic rolling lubrication.
A novel fullerene-styrene-maleic anhydride copolymer is reported.TEM analyses shows it is water-soluble nanoball of average diameter of about 83 nm.The tribological behavior is evaluated by four-ball machine. It was found that addition of fullerene copolymer to base stock(2% triethanolamine aqueous solution)resulted in a raise in load-carrying ability(F value)from 130 N to maximum 480 N,and a reduction in coefficient of frivtion from 0.235 to minimum 0.063.SEM analyses indicates that the wear scars obtained with fullerene copolymer exhibited mild scratches,while sharp grooving and serious pull-out phenomnon were observed in the presence of base stock without additive.The improvements in friction,wear and load-carrying capacity are probably due to the presence of fullerene copolymer nanoballs,which may act as molecule ball bearings,which in turn lead to elastic rolling lubrication.
2000, 14(3).
Abstract:
Labyrinth seal can cause steam-exciting,the structural and operation parameters of labyrinth seal have effect on stability of rotor-system.For investigating the coupling influences of the structure and operating parameters of labyrinth seals on dynamic coeffcients,a model of calculating dynamic coeffcients of labyrinth seals is presented using a two control volume model. The coupling influences of parameters on cross-coupled stiffness and direct damping of labyrinth seal are discussed. In the conclusion,a reference of preventing steam-exciting vibration and optimum determination of design parameters of labyrinth seals are provided.
Labyrinth seal can cause steam-exciting,the structural and operation parameters of labyrinth seal have effect on stability of rotor-system.For investigating the coupling influences of the structure and operating parameters of labyrinth seals on dynamic coeffcients,a model of calculating dynamic coeffcients of labyrinth seals is presented using a two control volume model. The coupling influences of parameters on cross-coupled stiffness and direct damping of labyrinth seal are discussed. In the conclusion,a reference of preventing steam-exciting vibration and optimum determination of design parameters of labyrinth seals are provided.
2000, 14(3).
Abstract:
The fuzzy sets theory is introduced into the fatigue reliability analysis.The concepts of maximizing set and minimizing set are developed to decide the ordering value of each fuzzy number,and these values can be used to determine the order of the fuzzy number.On the basis of the works mentioned above,the membership function defining the fuzzy safety event can be calculated,and then the fuzzy relibility in the case of random stress and fuzzy fatigue strength is deduced.An example is given to illustrate the method.
The fuzzy sets theory is introduced into the fatigue reliability analysis.The concepts of maximizing set and minimizing set are developed to decide the ordering value of each fuzzy number,and these values can be used to determine the order of the fuzzy number.On the basis of the works mentioned above,the membership function defining the fuzzy safety event can be calculated,and then the fuzzy relibility in the case of random stress and fuzzy fatigue strength is deduced.An example is given to illustrate the method.
2000, 14(3).
Abstract:
A new type of robust trajectory tracking control for harmonic using joint torque sensor and joint acceleration sensor information is concemed with.Joint torque sensor information is used to compensate the uncertainty of link and load parameters.Joint acceleration feedback control will enhace the robustness of the driving system,resist the dynamic uncertainties and disturbing torque acted on the joint axis within definite bandwidth,improve the joint tracking performance,and resist the vibration of the load side of the harminic drive system.Experimental studies are carried out and comparison of several controllers,such as PD and sensor-based control,the experimental results clearly illustrate the effectiveness of the proposed methods.
A new type of robust trajectory tracking control for harmonic using joint torque sensor and joint acceleration sensor information is concemed with.Joint torque sensor information is used to compensate the uncertainty of link and load parameters.Joint acceleration feedback control will enhace the robustness of the driving system,resist the dynamic uncertainties and disturbing torque acted on the joint axis within definite bandwidth,improve the joint tracking performance,and resist the vibration of the load side of the harminic drive system.Experimental studies are carried out and comparison of several controllers,such as PD and sensor-based control,the experimental results clearly illustrate the effectiveness of the proposed methods.
2000, 14(3).
Abstract:
The thermal behaviour of the solids under elastic deformations is analysed in order to obtain a model which combines the molecular dynamics results with the global thermal behaviour of the solids under elastic transformations.The result obtained consists of the introduction of the themal behaviour in the Parrinello-Rahman model,obtaining the thermal molecular dynamic model useful in the analysis of the thermoelastic behaviour of solids.
The thermal behaviour of the solids under elastic deformations is analysed in order to obtain a model which combines the molecular dynamics results with the global thermal behaviour of the solids under elastic transformations.The result obtained consists of the introduction of the themal behaviour in the Parrinello-Rahman model,obtaining the thermal molecular dynamic model useful in the analysis of the thermoelastic behaviour of solids.
2000, 14(3).
Abstract:
The hydrodynamic performances of a novel hydraulic shock generator are examined.The shock generator is designed to impose the strong power of waterhammer in mining industry.The experimental results show that the waterhammer produced by the periodic fast switch of a flowing fluid has diferent features with that of a single closure observed by other researchers.In particular,the intensity of the waterhammer depends largely on the switch frequency due to the interaction of successive pressure waves.These flow transient phenomena are theoretically proved by the simulation results based on the finite difference method of characteristics.
The hydrodynamic performances of a novel hydraulic shock generator are examined.The shock generator is designed to impose the strong power of waterhammer in mining industry.The experimental results show that the waterhammer produced by the periodic fast switch of a flowing fluid has diferent features with that of a single closure observed by other researchers.In particular,the intensity of the waterhammer depends largely on the switch frequency due to the interaction of successive pressure waves.These flow transient phenomena are theoretically proved by the simulation results based on the finite difference method of characteristics.
2000, 14(3).
Abstract:
The technuque of object-oriented feature-based solid modeling and its application in the CAD of hydraulic manifold block(HMB)are discussed.The research can greatly improve the convenience and efficienty of product design for HMB,as well as for the other mechanical products.
The technuque of object-oriented feature-based solid modeling and its application in the CAD of hydraulic manifold block(HMB)are discussed.The research can greatly improve the convenience and efficienty of product design for HMB,as well as for the other mechanical products.
2000, 14(3).
Abstract:
Considering machining effciency,surface quality and wear of cutter and machine,it is necessary to maintain high,stable and constant surface feed rate as far as possible.The feed rate control strategy for multi-axis CNC machining of free-form surfaces is presented.It comprises;①the determination of effective feed rate;②the adoption of suitable approaches to smooth feed rate.This strategy considers path geometry,actuator limitation and machine dynamics.The result shows that maching efficiency is improved effectively.
Considering machining effciency,surface quality and wear of cutter and machine,it is necessary to maintain high,stable and constant surface feed rate as far as possible.The feed rate control strategy for multi-axis CNC machining of free-form surfaces is presented.It comprises;①the determination of effective feed rate;②the adoption of suitable approaches to smooth feed rate.This strategy considers path geometry,actuator limitation and machine dynamics.The result shows that maching efficiency is improved effectively.
2000, 14(3).
Abstract:
A new type of hydraulic turbine and its design theory is presented.This turbine has the advantages of the most widely used Francis turbine and Straflo tubine,has its own specific theoretical basis,compact structure,small volume,low cost and steady operation.And it is conveninet to be transported,installed and maintained,and has good hydraulic and cavitation performance,It is named Straflo-Francis turbine.
A new type of hydraulic turbine and its design theory is presented.This turbine has the advantages of the most widely used Francis turbine and Straflo tubine,has its own specific theoretical basis,compact structure,small volume,low cost and steady operation.And it is conveninet to be transported,installed and maintained,and has good hydraulic and cavitation performance,It is named Straflo-Francis turbine.
2000, 14(3).
Abstract:
The concept of metamorphic mechanisms is presented,configuration models and configuration tranformations relating to a set of new matrix operations are discussed and proposed.The configuration of a metamorphic mechanism reflects the connectivity change in the mechanism during motions which results in mobility change and presents the characteristics of the mechanism which is discussed in various applications particularly in decorative artifacts.The characteristics is further investigated with mobility analysis.
The concept of metamorphic mechanisms is presented,configuration models and configuration tranformations relating to a set of new matrix operations are discussed and proposed.The configuration of a metamorphic mechanism reflects the connectivity change in the mechanism during motions which results in mobility change and presents the characteristics of the mechanism which is discussed in various applications particularly in decorative artifacts.The characteristics is further investigated with mobility analysis.
2000, 14(3).
Abstract:
The research and application of the punching machine driven by a linear induction motor(LIM)are introduced.The fundamental principle,construction,performance and application are described.Comparing this new model machine with its traditional form,the LIM driven punching machine has many great advantages,such as ,simple construction,small size and mass,low production cost,short production time,easy to control,low noise and considerable energy saving.
The research and application of the punching machine driven by a linear induction motor(LIM)are introduced.The fundamental principle,construction,performance and application are described.Comparing this new model machine with its traditional form,the LIM driven punching machine has many great advantages,such as ,simple construction,small size and mass,low production cost,short production time,easy to control,low noise and considerable energy saving.
2000, 14(3).
Abstract:
In order to realize high speed machining,the special requirements for the transmission and sturctrue of CNC machine tool have to be satisfied. A high speed spindle unit driven by a buit-in motor is developed.An oil-water heat exchange system is used for cooling the spindle motor.The spindle is supported by Si4N3 ceramic ball angular contact bearings.An oil-air lubricator is used to lubricate and cool the spindle bearings.Some special structures are taken for balancing the spindle.
In order to realize high speed machining,the special requirements for the transmission and sturctrue of CNC machine tool have to be satisfied. A high speed spindle unit driven by a buit-in motor is developed.An oil-water heat exchange system is used for cooling the spindle motor.The spindle is supported by Si4N3 ceramic ball angular contact bearings.An oil-air lubricator is used to lubricate and cool the spindle bearings.Some special structures are taken for balancing the spindle.
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