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10 December 1998, Volume 20 Issue 6
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    Review
    1998, 20(6):  1-6.  doi:10.6052/1000-0992-1999-353
    Abstract ( 1440 )   PDF (259KB) ( 930 )  
    The framework of modern soil mechanics is expected to be formed within the coming 30 years. The modern soil mechanics will be mainly composed of a new kind of constitutive model, a deformation theory (Consolidation theory of unsaturated soils)and two failure theories (Theory of liquefaction failure and theory of progressive failure), from the view point of the author. In this paper some recent developments and the key topics of its further research are discussed.
    Application study
    1998, 20(6):  7-9.  doi:10.6052/1000-0992-1999-354
    Abstract ( 1115 )   PDF (94KB) ( 575 )  
    In this paper, two simulated material models, one contains some initial joints and another contains no initial joints, are employed to investigate systematically the influence of initial joints on the surface subsidence. Moreover, within the framework of damage mechanics,the influence and effect of initial joints on the surface subsidence are investigated, and the empirical relation between the characteristic value of surface subsidence and damage variable is obtained
    1998, 20(6):  10-11.  doi:10.6052/1000-0992-1999-355
    Abstract ( 1021 )   PDF (162KB) ( 738 )  
    This paper proposes a finite element method for the stress analysis of nonhomogeneous medium. The concept of isoparametric transformation is adopted for simulating the variations of material properties in finite elements. The example shows that this improved FEM has higher efficiency and higher accuracy for analyzing nonhomogeneous medium.
    1998, 20(6):  12-14.  doi:10.6052/1000-0879-1999-356
    Abstract ( 1214 )   PDF (465KB) ( 655 )  
    Equations of motion for two spatial flexible links robot arm system in terms of real-quasi-coordinates,which deriving from Lagrange equations of the flexible bodies in terms of quasi-coordinates,are presented.By using of the quasi-coordinates and matrix operations,the lengtly and tedious process for derivation withrespect to the direction parameters are avoided,the composition of equations are compacted and it will causethe recursive formulation conveniently.Because the forms of the motion equations do not ...
    1998, 20(6):  15-17.  doi:10.6052/1000-0992-1999-357
    Abstract ( 1187 )   PDF (264KB) ( 584 )  
    The forming process of heated pushing curved tubes through an ox-core, including its temporal state of stress and strain and their evolution process is analyzed experimentally, the characteristics of its force and deformation are obtained, which may serve a foundation for its plastic analysis.
    1998, 20(6):  18-20.  doi:10.6052/1000-0992-1999-358
    Abstract ( 1083 )   PDF (173KB) ( 811 )  
    In this paper, a special pressure level, named characteristic pressure, at which the stiffness of the airbag is changed from linear to non-linear one, was found through experiment investigation on the relationship between the initial pressure and the stiffness of the airbag. In addition, the effect of structure, dimension and attenuation property on the characteristic pressure was studied.
    1998, 20(6):  21-23.  doi:10.6052/1000-0992-1999-359
    Abstract ( 1060 )   PDF (322KB) ( 715 )  
    In the paper the nonlinear dynamic equation of a beam under a follower force is derived, with the viscoelastic effects taken into account. The Melnikov function method is used to give the critical condition for chaotic motion. A demonstrative example is discussed through the Poincare mapping, phase portrait and time history. Finally the path to chaotic motion is also discussed.
    1998, 20(6):  24-26.  doi:10.6052/1000-0992-1999-360
    Abstract ( 1228 )   PDF (160KB) ( 669 )  
    The Accurate Integration Method for solving nonlinear dynamics problems is introduced. An example of numerical solution of a nonlinear problem proves that this method is valid.
    1998, 20(6):  27-28.  doi:10.6052/1000-0992-1999-361
    Abstract ( 1164 )   PDF (153KB) ( 605 )  
    The new strategy for the deployment of tethered satellite is presented, which is similar to the idea of Hohmann transfer. The dynamics is studied, and the transfer condition is derived from the orbital equations and Kepler′s equation. At last, a numerical example is given .
    1998, 20(6):  29-31.  doi:10.6052/1000-0992-1999-362
    Abstract ( 1170 )   PDF (250KB) ( 526 )  
    In this paper, an analysis of coupled vibration for the flexible spin rocket launch system with a supersonic exhaust jet is presented. Dynamic equations of the system are established, and the flow field structure inside the launch tube is described by a numerical simulation method. Transient responses of the launch system are given and the effect of exhaust jet on the rocket attitude is discussed. This work provides a more reliable and efficient approach to simulate the dynamics environment of the flexible...
    1998, 20(6):  32-34.  doi:10.6052/1000-0992-1999-363
    Abstract ( 1019 )   PDF (168KB) ( 596 )  
    The wear conditions of ram wheels are simulated by computer. By using the program ADINA the distributions of stresses of ram wheels are calculated. On the basis of strength theory wear limits are obtained.According to the information recorded during service, it can be seen that if wear depth is less than the wear limit, the ram wheels may continue working for a period of time.
    1998, 20(6):  35-36.  doi:10.6052/1000-0992-1999-364
    Abstract ( 844 )   PDF (83KB) ( 996 )  
    TSP problem is a typical combination optimum problem, and is a famous problem of operation research. For n nodes TSP problem, the calculation order is O((n-1)!) by searching method. When n is large, searching method is not a realistic choice. In this paper, a new method to resolve TSP problem—element division method is proposed. By this method, the computing amount is small, the result of calculation is accurate.
    1998, 20(6):  37-38.  doi:10.6052/1000-0992-1999-365
    Abstract ( 1029 )   PDF (84KB) ( 684 )  
    The experiments for anchor equipment and casing have been made by use of simulated equipment on ground. Strains on surface of casing are measured by using strain gauge. Strains of calculating element in each node are obtained on the basis of experimental data. In the numerical calculations finite element methods are used. Distributions of clenching power on each clenching tooth are obtained. Reliable data are provided for design of slip.
    1998, 20(6):  39-40.  doi:10.6052/1000-0992-1999-366
    Abstract ( 1090 )   PDF (156KB) ( 664 )  
    Polythene and polystyrene cushioning materials are viscoelastic materials. Their stress relaxation test curves are studied by a successive residual method. It is shown that the stress relaxation test curves may be expressed by finite number of Maxwell models interconnected in parallel.
    1998, 20(6):  41-44.  doi:10.6052/1000-0992-1999-367
    Abstract ( 1003 )   PDF (254KB) ( 540 )  
    This paper studies the theory of “three point bending”wirerope tension meter and the relationship between the tension T and the output values P,δ. It is shown that the bending stiffness EI of wirerope can not be neglected and it varies with tension T.A reasonable length of the calibrater for wire rope tension meter is also obtained.
    1998, 20(6):  45-50.  doi:10.6052/1000-0992-1999-368
    Abstract ( 901 )   PDF (314KB) ( 617 )  
    This paper shows from the experimental data that the concrete′s strength under the biaxial tension is lower than its uniaxial tensile strength. The weakening effect reaches 15%~30%. This is an important problem for the modern large span reinforced concrete plate and shell structure.