1996 Vol.9(2)
Display Mode： |
1996, 10(2).
Abstract:
The electromechanical coupling vibration system of the rotor of the AMBs (Active Magnetic Bearings) acted by PD or PID adjuster is studied. On the basis of changing the voltage control to the electric current control and introducing the nonlinear element, the self-excited vibration and Hopf bifurcation is studied using the morden analysis method in the nonlinear dynamics-Averaging method and center manifold theorem, as the result, the relationship between the vibration of rotor and the parameters of control system is analzed.
The electromechanical coupling vibration system of the rotor of the AMBs (Active Magnetic Bearings) acted by PD or PID adjuster is studied. On the basis of changing the voltage control to the electric current control and introducing the nonlinear element, the self-excited vibration and Hopf bifurcation is studied using the morden analysis method in the nonlinear dynamics-Averaging method and center manifold theorem, as the result, the relationship between the vibration of rotor and the parameters of control system is analzed.
CALCULATION OF LIMIT GLISSINESS OF NATURAL GRANITE AND THEORETICAL ANALYSIS OF SOFT POLISHING EFFECT
1996, 10(2).
Abstract:
A computational method for the limit glossiness is given which can theoretically forecast the probable finishing glossiness. Obviously microculting mark can't be found as scanning the polished surface, this indicates that the axial force has no great influence on the soft polishing. According to the analysis of the temperature field of polished surface and the thermal stress, it is concluded that temperature does a good effect on polishing. And on the base of test and variance analysis, it shows that chemical additive has a notable influence on the soft-dise polishing of natural granite.
A computational method for the limit glossiness is given which can theoretically forecast the probable finishing glossiness. Obviously microculting mark can't be found as scanning the polished surface, this indicates that the axial force has no great influence on the soft polishing. According to the analysis of the temperature field of polished surface and the thermal stress, it is concluded that temperature does a good effect on polishing. And on the base of test and variance analysis, it shows that chemical additive has a notable influence on the soft-dise polishing of natural granite.
1996, 10(2).
Abstract:
The valence electron structure of Ni containing austenite-martensite interface is calculated. The results show that Ni containing interface not only has higher electron density, but also has better continuity and stability. According to these results, phase transformation toughening mechanism and the interface behaviour of alloy elements can be explained with the valence electron structure of the interface.
The valence electron structure of Ni containing austenite-martensite interface is calculated. The results show that Ni containing interface not only has higher electron density, but also has better continuity and stability. According to these results, phase transformation toughening mechanism and the interface behaviour of alloy elements can be explained with the valence electron structure of the interface.
1996, 10(2).
Abstract:
A kind of four-wheel steering system is introduced, which is powered hydraulically and controlled by a single piece processor. This system is different from current steering system in all aspects. When a turning action occurs, the four wheels turn simultaneously, and every wheel can turn in the range of 180°. Under the control of the single piece processor, the vehicle body can move in any direction with given form and no dead zone in the range of 360°. The wheels are driven by rack cylinders which are controlled by proportional direction valve and powered by a hydraulic station. This system is suitable for any load, and the synchronism tolerance of the four wheels is less than 2.1°.
A kind of four-wheel steering system is introduced, which is powered hydraulically and controlled by a single piece processor. This system is different from current steering system in all aspects. When a turning action occurs, the four wheels turn simultaneously, and every wheel can turn in the range of 180°. Under the control of the single piece processor, the vehicle body can move in any direction with given form and no dead zone in the range of 360°. The wheels are driven by rack cylinders which are controlled by proportional direction valve and powered by a hydraulic station. This system is suitable for any load, and the synchronism tolerance of the four wheels is less than 2.1°.
1996, 10(2).
Abstract:
Greep-fatigue tests were performed at constant maximum stress in a range of high a lternating stress. On basis of the developed testing technique for measurement of dynamic back stress, a series of creep-fatigue resistances are measured at high alternating stress.The relevent creep-fatingue strain rate equation expressed by dynamic effctive stress is established. The microstructure observations on TEM explain the influence of high alternating stress on creep-fatigue resistance and give a deep understanding of the dependence of creep-fatigue strain rate and fracture life on the high alternating stress. The deformation mechanisms according to the observation microstructure on TEM is consistent with that expected on basis of the stress exponent of the creep-fatiue strain rate equation.
Greep-fatigue tests were performed at constant maximum stress in a range of high a lternating stress. On basis of the developed testing technique for measurement of dynamic back stress, a series of creep-fatigue resistances are measured at high alternating stress.The relevent creep-fatingue strain rate equation expressed by dynamic effctive stress is established. The microstructure observations on TEM explain the influence of high alternating stress on creep-fatigue resistance and give a deep understanding of the dependence of creep-fatigue strain rate and fracture life on the high alternating stress. The deformation mechanisms according to the observation microstructure on TEM is consistent with that expected on basis of the stress exponent of the creep-fatiue strain rate equation.
1996, 10(2).
Abstract:
An active control method to suppress the elastodynamic response of a flexible linkage is proposed. Computer-controlled piezoelectric ceramics are used as the actuators for producing the control moments. In addition, the linear quadratic optimal control theory is employd to design the control regulator with state feedback. A numerical simulation is carride out for examining the effectiveness of the active control.
An active control method to suppress the elastodynamic response of a flexible linkage is proposed. Computer-controlled piezoelectric ceramics are used as the actuators for producing the control moments. In addition, the linear quadratic optimal control theory is employd to design the control regulator with state feedback. A numerical simulation is carride out for examining the effectiveness of the active control.
1996, 10(2).
Abstract:
A method for calculating the static and dynamic performances and optimizing the parameters of a gas-lubricated tilting flat-sector-pad thrust bearing is introduced. Some optimized parameters such as diameter ratio and the pivot location of the pad are obtained. Using the program developed by the authors a rational design of the bearing is realized. The feasibility of such bearing is verified by a running test and the measured film thickness under different angular speed is fairly in agreement with the theoretical analyses.
A method for calculating the static and dynamic performances and optimizing the parameters of a gas-lubricated tilting flat-sector-pad thrust bearing is introduced. Some optimized parameters such as diameter ratio and the pivot location of the pad are obtained. Using the program developed by the authors a rational design of the bearing is realized. The feasibility of such bearing is verified by a running test and the measured film thickness under different angular speed is fairly in agreement with the theoretical analyses.
1996, 10(2).
Abstract:
The uncertainty of the domain knowledge in building expert system for diagnosis is analysed, and a fuzzy diagnostic model, based on fuzzy set theory, is proposed to deal with the domain knowledge description and the uncertain reasoning. It was pointed out that diagnostic weight matrix is the concentrated reflection of the diagnostic experience of domain experts. Based on the method of induction learning, the renew algorithm of diagnostic weight matrix is given to improve the accuracy of diagnostic reasoning.
The uncertainty of the domain knowledge in building expert system for diagnosis is analysed, and a fuzzy diagnostic model, based on fuzzy set theory, is proposed to deal with the domain knowledge description and the uncertain reasoning. It was pointed out that diagnostic weight matrix is the concentrated reflection of the diagnostic experience of domain experts. Based on the method of induction learning, the renew algorithm of diagnostic weight matrix is given to improve the accuracy of diagnostic reasoning.
1996, 10(2).
Abstract:
The paper addresses how to design elastic constraints in a vibration isolation system, which is a crucial problem found in engineering practice. It is pointed out that the constraint space designed according to the classical linear theory is usually so small that the isolation system most likely undergoes nonlinear resonances in the case of small damping. As a result, the isolation system becomes a vibration amplifier. Then, the design of elastic constraints is analysed from the viewpoint of nonlinear dynamics, and some design principles, as well as the selection range of parameters are discussed.
The paper addresses how to design elastic constraints in a vibration isolation system, which is a crucial problem found in engineering practice. It is pointed out that the constraint space designed according to the classical linear theory is usually so small that the isolation system most likely undergoes nonlinear resonances in the case of small damping. As a result, the isolation system becomes a vibration amplifier. Then, the design of elastic constraints is analysed from the viewpoint of nonlinear dynamics, and some design principles, as well as the selection range of parameters are discussed.
1996, 10(2).
Abstract:
A Statistical Energy Analysis (SEA) model on L-shaped thick plate structures including the coupling bending with in-plane waves is presented, and then the effect of shear, rotary inertia and in-plane waves on vibrational power flow is attended. Based on the model some calculating results can be expected to promote and complement for SEA.
A Statistical Energy Analysis (SEA) model on L-shaped thick plate structures including the coupling bending with in-plane waves is presented, and then the effect of shear, rotary inertia and in-plane waves on vibrational power flow is attended. Based on the model some calculating results can be expected to promote and complement for SEA.
1996, 10(2).
Abstract:
Based on the FEM (3-dimensional finite element method) and plastic increment in flow theory, a constitutive equation is derived, as well as a constitutive matrix of Mises model for uniform-strength materials under the action of complex stress. In FEM calculation, an accurate method of first order self-correction is introduced, and three kinds of boundary (I.e. free, adherent and sliding boundary) with contact elements applied are set up. The method of condensed matrix in association with FEM is used to solve the equation.
Based on the FEM (3-dimensional finite element method) and plastic increment in flow theory, a constitutive equation is derived, as well as a constitutive matrix of Mises model for uniform-strength materials under the action of complex stress. In FEM calculation, an accurate method of first order self-correction is introduced, and three kinds of boundary (I.e. free, adherent and sliding boundary) with contact elements applied are set up. The method of condensed matrix in association with FEM is used to solve the equation.
1996, 10(2).
Abstract:
The limitaitions of phenomenon-, material-or tribopair-oriented studies in tribology and the special nature of the knowledge of tribology are discussed. So that the potential benefit of tribology can be achieved more easily, extensions of understanding tribology, tribo-systems, the function of tribo-systems in machine systems and tribological design are suggested from the viewpoint of systems. The results have been considered in developing an expert system for the unbological design of cylinder liner ring packages. Some aspects of application are briefly introduced.
The limitaitions of phenomenon-, material-or tribopair-oriented studies in tribology and the special nature of the knowledge of tribology are discussed. So that the potential benefit of tribology can be achieved more easily, extensions of understanding tribology, tribo-systems, the function of tribo-systems in machine systems and tribological design are suggested from the viewpoint of systems. The results have been considered in developing an expert system for the unbological design of cylinder liner ring packages. Some aspects of application are briefly introduced.
1996, 10(2).
Abstract:
Based on the "Lifting surface theory" in automotive aerodynamics, a new theoretical model for predicting or determining the aerodynamic characteristics of an automobile is presented. Applicational potentialities of the new model in optimization of vehicle body design are also discussed, including those in the study and development of the "ideal basic body shapes", which have minimum drag coefficient when moving in the vicinity of the ground and satisfy all the requirements from automobile engineering and other aspects.
Based on the "Lifting surface theory" in automotive aerodynamics, a new theoretical model for predicting or determining the aerodynamic characteristics of an automobile is presented. Applicational potentialities of the new model in optimization of vehicle body design are also discussed, including those in the study and development of the "ideal basic body shapes", which have minimum drag coefficient when moving in the vicinity of the ground and satisfy all the requirements from automobile engineering and other aspects.
E-mail Alerts
