1995 Vol. 12 No. 4
Abstract：
In this paper the fundamental solution of a plate on elastic foundation is derived by Hankel transforms. which is suitable for all three different kinds of foundation Winkler,Pasternak and the elastic half-space model. For the generalized boundary value problem a complete set of baundary integral equations and the relevant numerical scheme are established.Finally the effectiveness of the proposed method is illustrated by several examples.
In this paper the fundamental solution of a plate on elastic foundation is derived by Hankel transforms. which is suitable for all three different kinds of foundation Winkler,Pasternak and the elastic half-space model. For the generalized boundary value problem a complete set of baundary integral equations and the relevant numerical scheme are established.Finally the effectiveness of the proposed method is illustrated by several examples.
1995, 12(4): 9-16.
Abstract：
As far as concrete is concerned, before the unstable propagation of crack, nonlinear deformation has been produced because of microcracks at crack tip and accompanied with prepropagation of crack. The nonlinear deformation and prepropagation make concrete absorb much more energy before fracture. In this paper, the nonlinear fracture toughness GIc which resists the crack propagation is obtained from the nonlinear load-displacement curve in experiments. The influences of notched length to specimen height ratio and the specimen height on GIc are investigated.
As far as concrete is concerned, before the unstable propagation of crack, nonlinear deformation has been produced because of microcracks at crack tip and accompanied with prepropagation of crack. The nonlinear deformation and prepropagation make concrete absorb much more energy before fracture. In this paper, the nonlinear fracture toughness GIc which resists the crack propagation is obtained from the nonlinear load-displacement curve in experiments. The influences of notched length to specimen height ratio and the specimen height on GIc are investigated.
Abstract：
The problems of the analysis of the rigid pavement on the multiple layered elastic foundation are studied by semi-analytical infinite layer method. A corresponding computer program had been developed. The result of a practical problem shows that the method of this paper is efficient.
The problems of the analysis of the rigid pavement on the multiple layered elastic foundation are studied by semi-analytical infinite layer method. A corresponding computer program had been developed. The result of a practical problem shows that the method of this paper is efficient.
1995, 12(4): 24-27.
Abstract：
The concept about simulation diagnosis is presented in this paper.Several Simulation methods for fault diagnosis of rotor-bearing system are studied.Simulation Diagnosis is an important supplemtentary method to the present techniques of fault diagnosis.A fault can be recognized both quantitatively and qualitatively with computer simulation.The bisection method isused for the diagnosis of a single fault.The methods are verified with laboratory test.
The concept about simulation diagnosis is presented in this paper.Several Simulation methods for fault diagnosis of rotor-bearing system are studied.Simulation Diagnosis is an important supplemtentary method to the present techniques of fault diagnosis.A fault can be recognized both quantitatively and qualitatively with computer simulation.The bisection method isused for the diagnosis of a single fault.The methods are verified with laboratory test.
Abstract：
The differential equations about Young's modulus and Poisson's ratio of foamed plastics are directly derived by differential scheme of composite mechanics and analyses of micromechanics. The approximate formulae for theoretical prediction of Young's modulus are obtained from the discussion of the equations, and expressed in simple forms. A good agreement with expermiental results has been reached. It is indicated that the formulae can be easily used in engineering.
The differential equations about Young's modulus and Poisson's ratio of foamed plastics are directly derived by differential scheme of composite mechanics and analyses of micromechanics. The approximate formulae for theoretical prediction of Young's modulus are obtained from the discussion of the equations, and expressed in simple forms. A good agreement with expermiental results has been reached. It is indicated that the formulae can be easily used in engineering.
1995, 12(4): 36-46.
Abstract：
For the study of damper application and structure-tuned liquid damper(TLD) interaction. a new mathematical model of liquid sloshing in an annular tank is presented. Forced vibration responses as well as free sloshing characteristics are elaborately examined by both shaking table experiments and theoretical analysis. Reasonable agreement is found between experimental results and theoretical analysis. Therefore the validity of the model is confirmed.
For the study of damper application and structure-tuned liquid damper(TLD) interaction. a new mathematical model of liquid sloshing in an annular tank is presented. Forced vibration responses as well as free sloshing characteristics are elaborately examined by both shaking table experiments and theoretical analysis. Reasonable agreement is found between experimental results and theoretical analysis. Therefore the validity of the model is confirmed.
Abstract：
A series of models are presented in this paper which deal with the shear strength analysis of simply-supported concrete beams under distributed load. Some reasonable assumptions and a distinctive discretization method are introduced into the models which combines the modified theory with the softened truss model. Tests are conducted to verify the theoretical models.
A series of models are presented in this paper which deal with the shear strength analysis of simply-supported concrete beams under distributed load. Some reasonable assumptions and a distinctive discretization method are introduced into the models which combines the modified theory with the softened truss model. Tests are conducted to verify the theoretical models.
1995, 12(4): 55-63.
Abstract：
An object-oriented programming approach to conduct design of limit section strength of reinforced concrete members is presented in the paper. The approach, which involves numerical integration and solution to non-linear equations, encompasses the existing normal section strength theories of limit design principles which are charcterized by plane section assumption and failure of the outmost fibre when the ultimate compressive strain is reached.The algorithm has potential applications in the development of CAD softwares for the reinforced usability. maintainability and expansibility are achieved. The precision of results is also improved due to the reduction of one of the simplified procedures of rectangular stress contour.
An object-oriented programming approach to conduct design of limit section strength of reinforced concrete members is presented in the paper. The approach, which involves numerical integration and solution to non-linear equations, encompasses the existing normal section strength theories of limit design principles which are charcterized by plane section assumption and failure of the outmost fibre when the ultimate compressive strain is reached.The algorithm has potential applications in the development of CAD softwares for the reinforced usability. maintainability and expansibility are achieved. The precision of results is also improved due to the reduction of one of the simplified procedures of rectangular stress contour.
Abstract：
Some special constraint forms, such as constrained systems of a rope and pulleys,hydraulic support systems are used in engineering. Their applications result in some new mechanical problems. The effect of forced distribution of reactions and the symbiosis of static and hyperstatic characters for a multispan beam constrained by two special constraint systems are brought to light in this paper.
Some special constraint forms, such as constrained systems of a rope and pulleys,hydraulic support systems are used in engineering. Their applications result in some new mechanical problems. The effect of forced distribution of reactions and the symbiosis of static and hyperstatic characters for a multispan beam constrained by two special constraint systems are brought to light in this paper.
Abstract：
in this paper, based on the vector analysis and the warping torsion theory of curved thin-walled girders, a set of governing differential equations for the non-uniform torsion of thinwalled spatial helicoid girders is developed. The method of initial parameters is employed to solve for the bimoment B. The present theory. lays down the foundation for further analysis of thinwalled spatial helicoid girders.
in this paper, based on the vector analysis and the warping torsion theory of curved thin-walled girders, a set of governing differential equations for the non-uniform torsion of thinwalled spatial helicoid girders is developed. The method of initial parameters is employed to solve for the bimoment B. The present theory. lays down the foundation for further analysis of thinwalled spatial helicoid girders.
Abstract：
The arch dam is analyzed by the load distribution-stiffness method. The cracking section performance functions are set up according to the limit state of every combined internal force. The formula of the gradient vector of every performance function is derived, and the iterative and recurrence formulas of collapse probability of section are obtained. The reduction of the arch dam's degree of statical indeterminiacy is carried out according to the failure of the section. The cracking trajectory of arch dam is traced in accordance with the progression of cracking sections. The conditional probability vector of cracking trajectocy of arch dam is formed in terms of the progression of conditional probability of cracking section of arch dam.
The arch dam is analyzed by the load distribution-stiffness method. The cracking section performance functions are set up according to the limit state of every combined internal force. The formula of the gradient vector of every performance function is derived, and the iterative and recurrence formulas of collapse probability of section are obtained. The reduction of the arch dam's degree of statical indeterminiacy is carried out according to the failure of the section. The cracking trajectory of arch dam is traced in accordance with the progression of cracking sections. The conditional probability vector of cracking trajectocy of arch dam is formed in terms of the progression of conditional probability of cracking section of arch dam.
1995, 12(4): 93-101.
Abstract：
This paper is concerned with the finite element analysis of softening materials. Special attention is paid to the methods for overcoming the mesh sensitivity in the analysis. An introduction is first given to the gradient theory which is widely recognized as a theoretically sound method. Then an improved method is proposed on the basis of the former one to overcome the difficulties in it's numerical implementation. Several numerical examples are presented, including a softening bar under tension, a biaxial test simulation and a slope stability problem, to show the efficiency and reliability of the proposed method.
This paper is concerned with the finite element analysis of softening materials. Special attention is paid to the methods for overcoming the mesh sensitivity in the analysis. An introduction is first given to the gradient theory which is widely recognized as a theoretically sound method. Then an improved method is proposed on the basis of the former one to overcome the difficulties in it's numerical implementation. Several numerical examples are presented, including a softening bar under tension, a biaxial test simulation and a slope stability problem, to show the efficiency and reliability of the proposed method.
1995, 12(4): 102-108.
Abstract：
The transmission of ultrasonic waves in sonotrode-melt system is studied, and the temperature rise of sonotrode is detected. It is shown that the temperature rise results from the sonotrode's structure damping (internal friction), and is relevant to energy density of ultrasonic waves and to the characteristic impedance ratio between sonotrode and melt.
The transmission of ultrasonic waves in sonotrode-melt system is studied, and the temperature rise of sonotrode is detected. It is shown that the temperature rise results from the sonotrode's structure damping (internal friction), and is relevant to energy density of ultrasonic waves and to the characteristic impedance ratio between sonotrode and melt.
1995, 12(4): 109-114.
Abstract：
Multi-storey buildings and laminated rubber isolators are modelled as periodic systems in this paper. The receptance approach to periodic structure theory is applied to study the wave propagation and vibrational transmission into a base-isolated multi-storey building due to horizontal harmonic ground motion. The analysis is focused on the effects of the storey number of of the rubber, the mass of the intermediate steel plates and the structural parameters of the laminated rubber bearing. Numerical results are presented for the range of parameter values which encompass different situations encountered in real life.
Multi-storey buildings and laminated rubber isolators are modelled as periodic systems in this paper. The receptance approach to periodic structure theory is applied to study the wave propagation and vibrational transmission into a base-isolated multi-storey building due to horizontal harmonic ground motion. The analysis is focused on the effects of the storey number of of the rubber, the mass of the intermediate steel plates and the structural parameters of the laminated rubber bearing. Numerical results are presented for the range of parameter values which encompass different situations encountered in real life.
Abstract：
For metal materials with yielding plateau, the authors established piece-wise Ramberg-Osgood Relation and corresponding Failure Assessment Curve. The new established curve is based on piece-wise computed J-integral and stable equilibrium expression Kr=(Je/J)1/2. It can be used to carry out the fracture assessments of finite extension amount and tearing instability with higher precision. The newly plotted Failure Assessment Curve lays the foundation for the improvement of reliability of fracture assessment of materials with yielding plateau.
For metal materials with yielding plateau, the authors established piece-wise Ramberg-Osgood Relation and corresponding Failure Assessment Curve. The new established curve is based on piece-wise computed J-integral and stable equilibrium expression Kr=(Je/J)1/2. It can be used to carry out the fracture assessments of finite extension amount and tearing instability with higher precision. The newly plotted Failure Assessment Curve lays the foundation for the improvement of reliability of fracture assessment of materials with yielding plateau.
1995, 12(4): 124-130.
Abstract：
in this paper, the main points of the pre-processing for finite element analysis with CAGD technique are highlighted. The pre-processing is implemented by drawing finite element models with CAD software and digitalization of element models with CAGD technique. It avoids a large amount of data preparation and input and therefore has extensive signification in practice.
in this paper, the main points of the pre-processing for finite element analysis with CAGD technique are highlighted. The pre-processing is implemented by drawing finite element models with CAD software and digitalization of element models with CAGD technique. It avoids a large amount of data preparation and input and therefore has extensive signification in practice.
1995, 12(4): 131-138.
Abstract：
An endochronic damage constitutive model is proposed. The characteristics of the model are that the elasto-plastic properties and internal defects of concrete are described by endochronic theory and damage mechanics respectively, so that the concept of yield surface is not needed. The number of parameters is reduced significantly in the model which makes the model more applicable to engineering practice. The proposed model is used to analyze deformation and strength of roller compacted concrete specimens. The calculating results are in good agreement with experimental data, which can be used as guidance for RCC gravity and arch dam construction.
An endochronic damage constitutive model is proposed. The characteristics of the model are that the elasto-plastic properties and internal defects of concrete are described by endochronic theory and damage mechanics respectively, so that the concept of yield surface is not needed. The number of parameters is reduced significantly in the model which makes the model more applicable to engineering practice. The proposed model is used to analyze deformation and strength of roller compacted concrete specimens. The calculating results are in good agreement with experimental data, which can be used as guidance for RCC gravity and arch dam construction.
