1994 Vol.7(4)
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1994, 8(4).
Abstract:
The path generated by a linkage in general deviates from the specified path. In this paper, the deviation is analyzed based upon the reliability concept and a reliability-based optimal synthesis procedure is presented for path generating mechanisms. Both structural and mechanical errors are incorporated in the objective function. A four-bar path generating mechanism is considered for numerical illustration and the results are compared with those obtained by deterministic procedure. As expected, the presented approach is superior to the deterministic procedure.
The path generated by a linkage in general deviates from the specified path. In this paper, the deviation is analyzed based upon the reliability concept and a reliability-based optimal synthesis procedure is presented for path generating mechanisms. Both structural and mechanical errors are incorporated in the objective function. A four-bar path generating mechanism is considered for numerical illustration and the results are compared with those obtained by deterministic procedure. As expected, the presented approach is superior to the deterministic procedure.
1994, 8(4).
Abstract:
By carrying out researches on the CAD / CAM for hydraulic manifold blocks, the integrated software package—MBCADAM is developed, which deals with the design and manufacturing for hydraulic manifold blocks.
By carrying out researches on the CAD / CAM for hydraulic manifold blocks, the integrated software package—MBCADAM is developed, which deals with the design and manufacturing for hydraulic manifold blocks.
1994, 8(4).
Abstract:
By employing the oil-film damping technique, the vibration-proof ability of rolling slideways assemble can be improved remarkably without influencing its inherent advanced characteristics. This paper presents an investigation on dynamic modelling and parameter identification for rolling slideways assembly with damping oil-films on the basis of modal modification. The method combines theoretical calculation and experimental results effectively and can be used to carry out reliable simulation and parameter analysis instead of pure analytical method.
By employing the oil-film damping technique, the vibration-proof ability of rolling slideways assemble can be improved remarkably without influencing its inherent advanced characteristics. This paper presents an investigation on dynamic modelling and parameter identification for rolling slideways assembly with damping oil-films on the basis of modal modification. The method combines theoretical calculation and experimental results effectively and can be used to carry out reliable simulation and parameter analysis instead of pure analytical method.
1994, 8(4).
Abstract:
Through theoretical and experimental research about automatic polishing on the curved surfaces of the moulds, the limitation of the polishing method at constant pressure, which is adopted widely in the world, is analysed. Based on the analysis, a new polishing method at constant pressure intensity is proposed, and the corresponding governing equation and a comprehensive polishing parameter are given as well.
Through theoretical and experimental research about automatic polishing on the curved surfaces of the moulds, the limitation of the polishing method at constant pressure, which is adopted widely in the world, is analysed. Based on the analysis, a new polishing method at constant pressure intensity is proposed, and the corresponding governing equation and a comprehensive polishing parameter are given as well.
1994, 8(4).
Abstract:
A new, more actual approach for omitting small loads in a loading history was presented according to crack closure, and load interactive effects which are large on damage of components were studied. Intrinsic periodic spectrum block representing a damage element of a load history, a new concept, was put out. It has been proven by theoretic analysis and tests that the modes of constructing fatigue loading spectrum have little effect on damage of components, which will change the incomplete knowledges on constructing fatigue spectrum ago.
A new, more actual approach for omitting small loads in a loading history was presented according to crack closure, and load interactive effects which are large on damage of components were studied. Intrinsic periodic spectrum block representing a damage element of a load history, a new concept, was put out. It has been proven by theoretic analysis and tests that the modes of constructing fatigue loading spectrum have little effect on damage of components, which will change the incomplete knowledges on constructing fatigue spectrum ago.
1994, 8(4).
Abstract:
A recently developed procedure to capture the dynamic stiffening of an arbitrary flexible member in large overall motion accompanied by small elastic vibrations is presented. A mechanical system is considered as a multibody system, the flexible member can be considered as a flexible body in a flexible multibidy system. Having retained the nonlinearities up to an appropriate point in the analysis, the linearization is then performed properly so that the dynamic stiffening terms can be found naturaly, while the explicit formulation of the governing equations for the deformation motion is ultimately linear. Based on the procedure, the effects of dynamic stiffening are investigated qualitatively and quantitatively with analytical and numerical examples. The results are useful in computer aid analysis of the dynamic behavior of flexible mechanical systems.
A recently developed procedure to capture the dynamic stiffening of an arbitrary flexible member in large overall motion accompanied by small elastic vibrations is presented. A mechanical system is considered as a multibody system, the flexible member can be considered as a flexible body in a flexible multibidy system. Having retained the nonlinearities up to an appropriate point in the analysis, the linearization is then performed properly so that the dynamic stiffening terms can be found naturaly, while the explicit formulation of the governing equations for the deformation motion is ultimately linear. Based on the procedure, the effects of dynamic stiffening are investigated qualitatively and quantitatively with analytical and numerical examples. The results are useful in computer aid analysis of the dynamic behavior of flexible mechanical systems.
1994, 8(4).
Abstract:
In reliability design of fatigue under random loading, the influence of loading sequence must be considered. In order to avoid the uncertain hypothesis in the Miner's rule, ie.that the sum of damage equals one represents failure, this paper proposes the probabilistic relative Miner's rule. This paper also presents a new method for calculating reliability, ie.the synthetic method of Miner's rule and interference model. This model considers not only the influence of stress concentration, dimension and surface, but also the influence of stress amplitued and sequence.
In reliability design of fatigue under random loading, the influence of loading sequence must be considered. In order to avoid the uncertain hypothesis in the Miner's rule, ie.that the sum of damage equals one represents failure, this paper proposes the probabilistic relative Miner's rule. This paper also presents a new method for calculating reliability, ie.the synthetic method of Miner's rule and interference model. This model considers not only the influence of stress concentration, dimension and surface, but also the influence of stress amplitued and sequence.
1994, 8(4).
Abstract:
Suggests some calculating formulas and methods with respect to the damage evolving rate da/Dn I and the fatigue life Σoi and Σpi in varied history from uncrack to microcrack initiation until fracture for a crankshaft, which are suitable to stress concentration positions about its journal fillets and oil holes on a crankshaft, that it is undergone to bending, twisting and shearing loading and subjected to unsymmetric cyclic cyclic many-stage loading. Last the total life in whole process is estimated by ΣN=Σnoi+Σnpi.
Suggests some calculating formulas and methods with respect to the damage evolving rate da/Dn I and the fatigue life Σoi and Σpi in varied history from uncrack to microcrack initiation until fracture for a crankshaft, which are suitable to stress concentration positions about its journal fillets and oil holes on a crankshaft, that it is undergone to bending, twisting and shearing loading and subjected to unsymmetric cyclic cyclic many-stage loading. Last the total life in whole process is estimated by ΣN=Σnoi+Σnpi.
1994, 8(4).
Abstract:
This paper attrempted to solve the problem of scuffing mechanism on the basis of theories in three fields: Boundaty lubrication, Hydrodynamic lubrication and Surface contact.for lineasr contacting, a simple solution has been obtained.
This paper attrempted to solve the problem of scuffing mechanism on the basis of theories in three fields: Boundaty lubrication, Hydrodynamic lubrication and Surface contact.for lineasr contacting, a simple solution has been obtained.
1994, 8(4).
Abstract:
Systematic analyses have been made to three typical dispositions of walking vehicle leg, and their kinematic characteristics are obtained respectively.A reliable theoretical guidance for the selection of the form is provided.
Systematic analyses have been made to three typical dispositions of walking vehicle leg, and their kinematic characteristics are obtained respectively.A reliable theoretical guidance for the selection of the form is provided.
1994, 8(4).
Abstract:
A developing program and a theoretical research mode of pneumatic rock drill are provided. An ordered system for designing pneumatic rock drills is generally discussed, some important criteria of design are made, and mathematic models on the theoretical study are established. As an example of calculation, the rock drill of the type 7655 is taken to show the operation of the mode, and the results obtained are accordant with that of experiment.
A developing program and a theoretical research mode of pneumatic rock drill are provided. An ordered system for designing pneumatic rock drills is generally discussed, some important criteria of design are made, and mathematic models on the theoretical study are established. As an example of calculation, the rock drill of the type 7655 is taken to show the operation of the mode, and the results obtained are accordant with that of experiment.
1994, 8(4).
Abstract:
Controllable modification of cone-generated cylindric worm gearing has been carried out. The tooth contact state of modified gearing can be controlled by selecting the positions of contact points of worm surface and the correction amount of curvature. The modification machining can be conveniently implemented by changing the geometrical sizes and setting parameters of grinding wheel. Therefore the research has better scientific basis and practical value.
Controllable modification of cone-generated cylindric worm gearing has been carried out. The tooth contact state of modified gearing can be controlled by selecting the positions of contact points of worm surface and the correction amount of curvature. The modification machining can be conveniently implemented by changing the geometrical sizes and setting parameters of grinding wheel. Therefore the research has better scientific basis and practical value.
1994, 8(4).
Abstract:
An investigation has been made on the fine grain superplasticity of alloy, Cu-26.69% Zn-3.82% Al and its effect of superplastic deformation (SPD) on the shape memory effect (SME). This alloy has the behavior of the fine grain superplasticity and SME simultaneousty. The rolled structure of the alloy obtains equiaxial grains after the superplastic pretreatment. The alloy presents maximum total elogation of 545%, at the deformation temperature of 600℃ and the tensile rate of 0.5mm / min. After superplastic deformation, the memory effect of the alloy is remarkably inproved, the angle recovery rate and the enthalpies of transformation increase, the attenuation of SME decreases, and the characteristic temperatures are lowered.
An investigation has been made on the fine grain superplasticity of alloy, Cu-26.69% Zn-3.82% Al and its effect of superplastic deformation (SPD) on the shape memory effect (SME). This alloy has the behavior of the fine grain superplasticity and SME simultaneousty. The rolled structure of the alloy obtains equiaxial grains after the superplastic pretreatment. The alloy presents maximum total elogation of 545%, at the deformation temperature of 600℃ and the tensile rate of 0.5mm / min. After superplastic deformation, the memory effect of the alloy is remarkably inproved, the angle recovery rate and the enthalpies of transformation increase, the attenuation of SME decreases, and the characteristic temperatures are lowered.
1994, 8(4).
Abstract:
A method for precise calculation of tooth root stress of spiral bevel gears is presented and developed. On the basis of the machine settings analysis, tooth geometry analsis and loaded tooth contact analysis, by using the tooth surface distribution load from tooth load analysis, the calculation model is established and the root stress is calculated by means of finite element method. The method mentioned is verified by a tested gears example.
A method for precise calculation of tooth root stress of spiral bevel gears is presented and developed. On the basis of the machine settings analysis, tooth geometry analsis and loaded tooth contact analysis, by using the tooth surface distribution load from tooth load analysis, the calculation model is established and the root stress is calculated by means of finite element method. The method mentioned is verified by a tested gears example.
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