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10 April 2000, Volume 22 Issue 2
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    Research paper
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-031
    Abstract ( 805 )  
    Statistical analyses of tensile failures for fibers, fiber bundles and composites have been reviewed in this paper. Emphasis has been placed on both the statistical theories of crack propagation and the random critical-core theory for composite materials.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-033
    Abstract ( 786 )  
    This paper reviews the development of passive control technique in aseismic control of structural buildings. A range of devices including metallic, frictional, viscoelastic, viscous, tuned mass and tuned liquid dampers were briefly discussed in order to provide a broad perspective. The emphasis was on devices that have found or are likely to find application in civil engineering structures.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-034
    Abstract ( 867 )  
    The characteristics of configuration and operating principle of Collimated Abrasive Water Jets (CAWJ) and particle accelerating equation with energy loss in the collimating pipe are analyzed. Theoretical and experimental results show that particle speed of CAWJ retains constant basically as the pipe length is in the range of 0.4m to 3m. There is all optimal relationship between the parameters of the collimating pipes and abrasives. The application of CAWJ for cutting and breaking is discussed in this pape...
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-035
    Abstract ( 767 )  
    in this paper, based on Hahn-Tsai nonlinear theory, energy release rate and the delamination-tip fields of delamination of a laminated composite were analyzed by the quasi-3D FEM. The results indicate that the effect of material nonlinearity along thickness direction on energy release rate G (specially on GII) are significant and related to the post-buckling model of the laminates. Around the delamination-tip interlamminar stresses are reduced and displacements are increased obviously.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-036
    Abstract ( 806 )  
    Based on 3-D iso-parametric element and the plate shell element of relative displacement and combined with beam assumption, we proposed the degenerated 3 dimensional curved beam element with geometrical nonlinearity, which can be used for analysis of critical load of linear elastic buckling of beam and arch.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-037
    Abstract ( 785 )  
    The stability of the Rayleigh-Benard thermally driven flow is numerically computed with an operator transformation and the continuation method. The contours of stream function, vorticity and temperature are drawn for different values of Ra when Pr = 1.0; and the critical Ra number at several Pr numbers is about 2740. The result agrees with the physics analysis, and is also reasonable as compared with three-dimensional experiment.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-038
    Abstract ( 747 )  
    Based the theory of elasticity and that of fracture mechanics, the effect of a loaded specimen with crack on the travelling path of ultrasonic wave is studied. By comparing the result of light and ultrasonic waves, it is found that a loaded specimen with crack can be considered as a concave lens (mirror) for light wave and as a convex lens (mirror) for ultrasonic wave.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-039
    Abstract ( 858 )  
    in this paper, with the available computer method, the authors have obtained the stress distribution across sections of reinforced concrete composite beams under two stages of loading, and show that the stress redistribution under two stages of loading results in a reduction of stress discrepancy in the tensile steel and of strain discrepancy in the compressed concrete between the composite beam and the corresponding casting beam.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-040
    Abstract ( 796 )  
    During aircraft escape ejection, the force and the movement of pilot's limb before and after his hands slipping out of the center ring are studied. A 3-body model of limb is established by using principle of the virtual displacement and Kane's method. The force and movement are obtained under some aircraft escape ejection conditions.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-041
    Abstract ( 763 )  
    This paper has given an error analysis on several common girder under vertical and horizontal bending loads. The analysis is based on two methods: one is LISHEN, a finite-element method software, the other is stability formula in the constructional standards. A new coefficient is suggested to modify the standards formula.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-042
    Abstract ( 853 )  
    According to changes of basic parameters of soft wire shaft, other geometeric variations after loading are determined. Then relative twisting angle and twisting stiffness of soft wire shaft are obtained. Moreover, we have determined the twisting stiffness with twisting testing machine. The results demonstrate that theoretical calculation values are in agreement with the experimental ones.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-043
    Abstract ( 720 )  
    Longitudinal shock test and analysis on chimney models are made in this paper. Conclusion is that the fracture location of chimney models is related to the ratio of the shock wave period and chimney inherent period and only one circumferential crack will be produced by longitudinal shock.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-044
    Abstract ( 770 )  
    Based on the fundamental principle of rock mechanics, the stresses of single joint rock under real three-dimensional compression are analyzed in this paper. The discussion is centered on the effect of the middle-main-stress on the stresses of single joint rock. It is found that the, stresses of single joint rock are affected by the middle-main-stress, which may be the main factor in some conditions.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-045
    Abstract ( 798 )  
    in this paper, a new method of element analysis for curved bars with variable cross-section is proposed. The curved bar is taken as an element and by using the method of elastic centre to derive the general equation of the element stiffness matrix. The accurate equations of the element stiffness matrix are given when the cross-section of the bar vary according to cosine function and the centre line of the bar is circular, parabolic or elliptical. They can be used as a reference in the engineering design.
    2000, 22(2):  0-0.  doi:10.6052/1000-0879-f2000-046
    Abstract ( 841 )  
    The heat transfer characteristics of a closed two-phase thermosiphon at different incline angles are experimentally investigated. The working fluid is a mixture of methanol and water with different ratios. The axial temperature distribution at the heating wall is much different from that in the case of one-component (water) working fluid. There is also a difference between heat pipes working with different mixture ratios. This is due to the axial distribution of methanol concentration.