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10 June 2006, Volume 28 Issue 3
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    Application study
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2004-486
    Abstract ( 1384 )   PDF (437KB) ( 645 )  
    Based on Von Karman's nonlinear theory of plate and Kachanov's creep-damage theory, the nonlinear equilibrium equations are established for a rectangle plate with creep and damage, subjected to out-plane and in-plane loads simultaneously and simply supported on four sides. Using the finite-difference method, the equations are solved iteratively. The influence of several factors, such as geometrical nonlinearity and in-place loads, on the creep-damage behavior is discussed.
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2005-083
    Abstract ( 1364 )   PDF (469KB) ( 644 )  
    Dynamic analysis of elastic body for plates and shells is important and difficult. The method of convolution-type weighted residuals is a new method for solving dynamic problems of thin shells. It is shown to be effective in this paper.
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2005-144
    Abstract ( 1329 )   PDF (1470KB) ( 714 )  
    Using the high temperature fatigue testing system with scanning electron microscope, we observed the influence of temperature's change on limestone's microstructure in real time, effectively avoided the influence of the reversible process of rock's heat inflating, which is influenced by the history of temperature and the influence of the difference of its properties during heating and after cooling. And it was also found that the samples have not created hot cracks in the heating process, but have created lot of tiny cracks in the cooling process. The experimental results indicate that the rock's microstructure changes at heating process and cooling process are different. This may due to the residual stress produced in the cooling process of limestone.
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2005-168
    Abstract ( 5363 )   PDF (961KB) ( 612 )  
    Only the action of horizontal earthquake was considered generally when structure with MRD was analyzed. The correlation of movements in horizontal and vertical directions was not well studied. This paper considers the structure with MRD under bidirectional coupling earthquake. The dynamic analysis model is set up, kinetic differential equations are obtained, and dynamic time history analysis is made. Taking an 8-story structure with MRD for example, the results show that the seismic responses of the structure with MRD increase in some extent under the action of earthquake in vertical direction. Therefore, it is highly recommended that the influence of vertical earthquake action on such structures should be taken into account in high-intensity earthquake regions. The optimal model for structures with MRD is set up. The various earthquake responses of structures with MRD under various loading conditions can be better controlled after the optimization with IHGA.
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2005-187
    Abstract ( 1724 )   PDF (1009KB) ( 691 )  
    There are several advantages of adhesively bonded fiber reinforced polymer (FRP) laminates used for the deteriorated metallic members over the traditional retrofit methods susceptible to fatigue crack initiation. The three dimensional ``solid-spring-shell element'' finite element model is presented in the paper. In the FEM model, the metalic plate is modeled as a solid element, FRP is modelled as a shell element and the spring element is used to model the adhesion between the metalic plate and FRP. Linear fracture mechanics analysis of cracked metallic plates repaired with FRP is carried out. Influencing factors on the stress intensity factors at crack tips are discussed. It is shown that the increases in the elastic modulus or the thickness of FRP improve the effectiveness of strengthening significantly.
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2005-196
    Abstract ( 1329 )   PDF (565KB) ( 753 )  
    The rule of full stress is an efficient method in the optimal design for statically indeterminate shape steel truss. But the major shortcoming of this method is that the convergent speed is very slow. In this paper, a new area ratio method for the optimal design based on full stress is proposed on the basis of ``the direct method of stability design for shape steel columns'', in which the convergent speed of repeated calculations is greatly improved, and the design cost is effectively reduced.
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2005-198
    Abstract ( 1401 )   PDF (360KB) ( 705 )  
    Based on the principle of minimum potential energy with mixed variables for beams with large deflections, the paper presents an approximate method for cylindrical bending of large deflections of panels with two edges fixed. From the results it is shown that the method is effective and enjoys a high precision.
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2005-200
    Abstract ( 1465 )   PDF (433KB) ( 502 )  
    In this paper, the homogenization theory and higher order discrete-layer laminate model are applied to the flip-chip electronic package assemblies with underfills, with microstructures not completely periodic (single layer). The effective elastic properties for a laminar with BGA and underfills are determined by an analytic method. The numerical results are compared with the previous solutions, which shows the efficiency of the present model and method.
    2006, 28(3):  0-0.  doi:10.6052/1000-0879-2005-204
    Abstract ( 1290 )   PDF (618KB) ( 527 )  
    Based on the assumption that the shear force and the shear displacement between the bolt and the surrounding soil follow a perfect elasto-plastic model, an analytical solution for the anchor pullout resistance is derived. According to the field uplift tests of grouted bolts burried in mucky soil, the pullout resistance of bolt is calculated by the formula and compared with that directly obtained from tests. A good agreement is obtained.
    2006, 28(3):  0-0.  doi:10.6052/1000-0879-2005-212
    Abstract ( 1038 )   PDF (627KB) ( 568 )  
    Guiding-deflection technique is one of efficient technical ways to protect engineering constructions against precision-guided weapons. In this paper, ductalloy guiding-deflection cones (GDC) are adopted, and simulated impact tests with 37\,mm semi-armour piercing projectiles are carried out to test the guiding-deflection performance of the GDC structure. Test results indicate that the structure can make the projectile deflect more than 10 degrees, and the penetration depth into the target is reduced to less than its 1/3. On the basis of test results, the guiding-deflection mechanism of GDC as well as the test errors are analyzed, and a conclusion is reached that a space with as small resistance as possible behind the guiding-deflection structure is one of prerequisites to achieve large deflection angles. The guiding-deflection structure can be applied in some important engineering constructions of national defence and civil-air defence.
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2005-221
    Abstract ( 1438 )   PDF (1136KB) ( 738 )  
    This paper reviews the development of the fatigue damage accumulation theory and fatigue life prediction approaches for spot welds, including the fatigue life predicting methods, fatigue life prediction models, and factors affecting the fatigue strength of spot welds. It covers both theoretical and engineering aspects. Some comments are made on the further development of the life prediction methods.
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2005-235
    Abstract ( 1112 )   PDF (434KB) ( 561 )  
    This paper applies the finite-element method for beam of variable section and the programming language of MATLAB to analyze the buckling strength of whole-corrugated web H-beam under axial pressure, and the comparison with constant cross-section H-beam shows the superiority of whole-corrugated web H-beam.
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2005-276
    Abstract ( 1211 )   PDF (1070KB) ( 572 )  
    The BPM2D (Beam-Particle Model in Two Dimensions) is used to simulate the penetration and perforation of a plain concrete panel. The BPM2D is based on the DEM and the FEM. Three types of beam in the BPM2D are used in the numerical model of concrete, with their mechanical properties varying with their strain-rate and are randomly assigned according to Weibull distribution to reflect the initial heterogeneity of concrete at the mesoscale level. The failure process of a steel bullet perforating into a concrete panel is analyzed by this model. The velocity field in concrete and bullet at different impact velocities are obtained. The comparison of the simulated results with the experimental data and the simulated results of the code LS-DYNA3D shows that the BPM2D can be used to simulate the dynamic failure problems of brittle material.
    Around the mechanics
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2005-278
    Abstract ( 1115 )   PDF (609KB) ( 573 )  
    The calculating methods of the initial force and effective tensile force of prestressing tendon are given in this paper. The differential equation for the prestressed concrete filled steel tubular member is established, and the formulas for buckling load of the composite members are derived by using the theory of elasticity and the energy principle. On the basis of the strength condition, the limit slenderness ratio is deduced. The numerical examples show that the stability bearing capacity of the prestressed concrete filled steel tubular member exceeding the limit slenderness ratio can be raised by prestressing.
    Application study
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2006-029
    Abstract ( 1169 )   PDF (860KB) ( 549 )  
    How to reach a uniformly distributed temperature in a substrate radiatively heated in vacuum is one of the major issues in the thin film deposition. In this article, numerical calculations and infrared colorimetric measurements of temperature are made to analyze a radiation heater used in vacuum, named as IMCAS-VRH. IMCAS-VRH is used to heat a monocrystal silicon substrate with a diameter of 6 inches, under an electric power of 3\,860\,W. The mean temperature over the substrate is 1\,093\,K, while the whole temperature variation is within 6\,K. The calculated temperature distributions agree well with the measured data, and further computational analysis shows that the Mo filaments' shielding from radiation, the thermal insulation plates, and the thermal conductivity of the radiation cavity all affect significantly either the mean temperature or the temperature distribution uniformity in the substrate.
    2006, 28(3):  0-0.  doi:10.6052/1000-0992-2006-179
    Abstract ( 1502 )   PDF (2464KB) ( 910 )  
    Based on the researches on constructions in frozen regions and Qinghai-Tibet Roadway and Railway, some related mechanics problems are proposed. They are: the temperature field in frozen soil under climate and engineering conditions; frost heaving and thaw settlement of permafrost roadbed; the support force of frozen soil under the roadbed; the frost heaving of many kinds of engineering constructions (especially culverts and stake bases); the influence of regenerative damages on railway bed; active protective measures for frozen soil damages. All problems may be classified into two kinds: one concerns heat stability, and the other dynamics stability. And the both problems are coupled.