1994 Vol.7(2)
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1994, 8(2).
Abstract:
In the course of investigating the high pressure (maximum pressure 1200MPa) characteristics of lubricants produced in China, the authors met with several difficulties concerning the sealing under such high pressure and the conducting of signal from high pressure chamber to outside environment. Development work had been done and several techniques thus resulted which proved to be rather successful. They are high pressure all-metal viscoelastic moving seal, high pressure rheological plain packing, high pressure feedthrough leading electrical wire from packed hole and high pressure viewing window. They are described in this paper, and it is hoped that they might be useful to research workers engaged in this area of work.
In the course of investigating the high pressure (maximum pressure 1200MPa) characteristics of lubricants produced in China, the authors met with several difficulties concerning the sealing under such high pressure and the conducting of signal from high pressure chamber to outside environment. Development work had been done and several techniques thus resulted which proved to be rather successful. They are high pressure all-metal viscoelastic moving seal, high pressure rheological plain packing, high pressure feedthrough leading electrical wire from packed hole and high pressure viewing window. They are described in this paper, and it is hoped that they might be useful to research workers engaged in this area of work.
1994, 8(2).
Abstract:
After intercritical treatment, the structure and properties of 18SiMnCu cold rolled sheet steel is studied. When the sheet steel held at 780℃ and followed by 25℃ / s colling rate, a composite structure of (F+M+A) and optimum mechanical properties were obtainde:σs=300MPa, σb=750MPa, δ=27%, n=0.27. The transformation process of retained austenite was examined by x-ray and TEM.
After intercritical treatment, the structure and properties of 18SiMnCu cold rolled sheet steel is studied. When the sheet steel held at 780℃ and followed by 25℃ / s colling rate, a composite structure of (F+M+A) and optimum mechanical properties were obtainde:σs=300MPa, σb=750MPa, δ=27%, n=0.27. The transformation process of retained austenite was examined by x-ray and TEM.
1994, 8(2).
Abstract:
For the situation of multiple cooperating manipulators handling a single object, an equilibrium equation is presented in which the manipulator dynamics and control forces/torques are taken into account, and a expression is derived to allow the optimal dynamic load distribution of the combined system can be made.
For the situation of multiple cooperating manipulators handling a single object, an equilibrium equation is presented in which the manipulator dynamics and control forces/torques are taken into account, and a expression is derived to allow the optimal dynamic load distribution of the combined system can be made.
1994, 8(2).
Abstract:
The principle and method of flexible multibody system dynamics is presented. The dynamic equation have been developed by means of Huston's method based on Kane's equation. In which the flexible members with general cross-section characters were divided into finite segment models under the assumption of small strain. In order to decrease the degrees of freedom of the system and increase the efficiency of numerical calculation, the mode transformation has been introduced. A typical example is presented, and the foregoing method has been perfectly verified.
The principle and method of flexible multibody system dynamics is presented. The dynamic equation have been developed by means of Huston's method based on Kane's equation. In which the flexible members with general cross-section characters were divided into finite segment models under the assumption of small strain. In order to decrease the degrees of freedom of the system and increase the efficiency of numerical calculation, the mode transformation has been introduced. A typical example is presented, and the foregoing method has been perfectly verified.
1994, 8(2).
Abstract:
On basis of the computer a fuzzy design system is developed for the design of cam mechanisms. The system includes a fuzzy knowledge base, a virtual knowledge base, a fuzzy design mathematical model, a fuzzy design procedure which can complete the conventional fuzzy design and the fuzzy design optimisation. It can draw on the designer's wisdom better, and enhance the design quality and efficiency.
On basis of the computer a fuzzy design system is developed for the design of cam mechanisms. The system includes a fuzzy knowledge base, a virtual knowledge base, a fuzzy design mathematical model, a fuzzy design procedure which can complete the conventional fuzzy design and the fuzzy design optimisation. It can draw on the designer's wisdom better, and enhance the design quality and efficiency.
1994, 8(2).
Abstract:
The load condition of the mineral sizer is discussed. Acoording to three typical load cases presented, FEM and optimization models are extablished. Computed the model problems by use of ANSYS software and sequential unconstrained minimization technique, the stress distribution on crush tooth and it's optimal shape are aquired. After analyzing the results, the relation between stress distribution and structural parameters is presented.
The load condition of the mineral sizer is discussed. Acoording to three typical load cases presented, FEM and optimization models are extablished. Computed the model problems by use of ANSYS software and sequential unconstrained minimization technique, the stress distribution on crush tooth and it's optimal shape are aquired. After analyzing the results, the relation between stress distribution and structural parameters is presented.
1994, 8(2).
Abstract:
A new nonlinear optimization approach with discrete design variables based on linear estimation is proposed, in which the complex engineering structures optimization problems, such as 3-D space plate-system structures optimization problems, can be solved. By avoided using point-by-point searching strategy, which is usually used in other discrete optimization algorithms, the times of function calculation is greatly reduced.
A new nonlinear optimization approach with discrete design variables based on linear estimation is proposed, in which the complex engineering structures optimization problems, such as 3-D space plate-system structures optimization problems, can be solved. By avoided using point-by-point searching strategy, which is usually used in other discrete optimization algorithms, the times of function calculation is greatly reduced.
1994, 8(2).
Abstract:
Research shows that dynamic response is the origin of the phenomena. While a friction pair is in motion, the dynamic response force corresponding to the rate of elastoplastic deformation of contact makes the surfaces of the pair dynamically harden and separate a certain level from the equilibrium position. Consequently, the real area of contact decreases with an increase in sliding speed. While the friction pair comes to rest, the remaining process of dynamic response would not disappear instantaneously but will gradually return to normal position, and as a result the contact area is increased during the rest period. These processes appear as F-ν descent and F-t ascent characters. Because of the dynamic response, the real contact area is seriously decreased, consequently there occurs serious stress concentration and intensive wear. Thus, the dynamic response may be used to evaluate matching character of a friction pair. It is prospective that to study dynamic response of solid is of great significance on wear research. Conceptual and experimental explanation on dynamic response was introduced in 1981. But the concept is too abstract to understand. In order to imaginarily recongnize the phenomenon, by using the universality of natural law, the dynamic response in dry friction pair is simulated by thermodynamics. Thus, the concept of dynamic response is vividly depicted.
Research shows that dynamic response is the origin of the phenomena. While a friction pair is in motion, the dynamic response force corresponding to the rate of elastoplastic deformation of contact makes the surfaces of the pair dynamically harden and separate a certain level from the equilibrium position. Consequently, the real area of contact decreases with an increase in sliding speed. While the friction pair comes to rest, the remaining process of dynamic response would not disappear instantaneously but will gradually return to normal position, and as a result the contact area is increased during the rest period. These processes appear as F-ν descent and F-t ascent characters. Because of the dynamic response, the real contact area is seriously decreased, consequently there occurs serious stress concentration and intensive wear. Thus, the dynamic response may be used to evaluate matching character of a friction pair. It is prospective that to study dynamic response of solid is of great significance on wear research. Conceptual and experimental explanation on dynamic response was introduced in 1981. But the concept is too abstract to understand. In order to imaginarily recongnize the phenomenon, by using the universality of natural law, the dynamic response in dry friction pair is simulated by thermodynamics. Thus, the concept of dynamic response is vividly depicted.
1994, 8(2).
Abstract:
A new criterion of degree of freedom for planar mechanism was presented. Compared with Gruebler's equation, this criterion possesses some characteristics. On one hand, this equation needs no modifying to the complex hinges, degrees of local freedom, and the case of mechanism with all sliding pairs. On the other hand, synthesing the concepts of substitution higher pair for kinematically equivalent lower pair, DOF determination and evolution, which benefits the students in learning. Hence, the authors suggest the formula be recommended, since its briefness, easiness to grasp.
A new criterion of degree of freedom for planar mechanism was presented. Compared with Gruebler's equation, this criterion possesses some characteristics. On one hand, this equation needs no modifying to the complex hinges, degrees of local freedom, and the case of mechanism with all sliding pairs. On the other hand, synthesing the concepts of substitution higher pair for kinematically equivalent lower pair, DOF determination and evolution, which benefits the students in learning. Hence, the authors suggest the formula be recommended, since its briefness, easiness to grasp.
1994, 8(2).
Abstract:
On the conditions of the width to thickness ratio 625 and the centre wave the 3-dimensional stresses distributions of cold strip rolling are studied by using the third power spline function finite strip method. The computed results of the rolling pressure, the 2-directional friction stresses and the front and back tension stresses agree with the experimental results well. In this paper, the frictional stresses of stagnation zone are computed by using preliminary displacement principle and the computing precision is improved.
On the conditions of the width to thickness ratio 625 and the centre wave the 3-dimensional stresses distributions of cold strip rolling are studied by using the third power spline function finite strip method. The computed results of the rolling pressure, the 2-directional friction stresses and the front and back tension stresses agree with the experimental results well. In this paper, the frictional stresses of stagnation zone are computed by using preliminary displacement principle and the computing precision is improved.
1994, 8(2).
Abstract:
An unlubricated sliding friction test on C/Cu composite materials is described. The result of the test proves that adhesive wear is the domination. At a certain speed, when the load upon the test block is light, the wear rate remains low level and the friction pair has a good antifriction performance. But when the load increases to a certain value, the wear transitions happen, the wear becomes severe.
An unlubricated sliding friction test on C/Cu composite materials is described. The result of the test proves that adhesive wear is the domination. At a certain speed, when the load upon the test block is light, the wear rate remains low level and the friction pair has a good antifriction performance. But when the load increases to a certain value, the wear transitions happen, the wear becomes severe.
1994, 8(2).
Abstract:
According to property requirement of differential, create a new mechanism, which is a combination of a paralleogram linkage and a inverse parallelogram linkage, to replace conventional bevel gears of differential and point out that using the new mechanism the differential can meet the needs of the requirements of torque and speed of the two axle shafts. The instantaneous speed ratio (ISR) which is the left and right half-shaft with respect to differential shell is variable. The calculating result of the locking factor of the new mechanism is up to 3. The limited-slip capability increase twice. The mechanism is an ideal new type of mechanism of differential.
According to property requirement of differential, create a new mechanism, which is a combination of a paralleogram linkage and a inverse parallelogram linkage, to replace conventional bevel gears of differential and point out that using the new mechanism the differential can meet the needs of the requirements of torque and speed of the two axle shafts. The instantaneous speed ratio (ISR) which is the left and right half-shaft with respect to differential shell is variable. The calculating result of the locking factor of the new mechanism is up to 3. The limited-slip capability increase twice. The mechanism is an ideal new type of mechanism of differential.
1994, 8(2).
Abstract:
A new experimental apparatus is designed to study nonlinear vibration characteristics of flexible mechanisms under excitation with single pumping frequency at fixed position. It is found that the dynamic responses express strongly nonlinear vibration characteristics if the links are flexible enough. There are several harmonic frequencies under first fundamental natural frequency which is determined by finite element method, then the combination harmonic method in nonlinear vibration theory is used to determine the critical speeds of a flexible mechanism, which are verified by the experimental results.
A new experimental apparatus is designed to study nonlinear vibration characteristics of flexible mechanisms under excitation with single pumping frequency at fixed position. It is found that the dynamic responses express strongly nonlinear vibration characteristics if the links are flexible enough. There are several harmonic frequencies under first fundamental natural frequency which is determined by finite element method, then the combination harmonic method in nonlinear vibration theory is used to determine the critical speeds of a flexible mechanism, which are verified by the experimental results.
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