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10 June 2003, Volume 25 Issue 3
Application study
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2002-204
Abstract ( 1336 )   PDF (200KB) ( 705 )
This paper describes the differential quadrature method briefly. It is used in the nonlinear vibration analysis of simple pendulum, and result obtained is better than the L-P method.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2002-233
Abstract ( 970 )   PDF (205KB) ( 528 )
The equivalent relation between the spherical and cylindrical particles was built, and the method of equivalent surface area was used to calculate the drag exerted on the cylindrical particle. Then the finite-volume method was applied to obtain the drag numerically. It is found that the drag obtained by the numerical method differs from that obtained by the equivalent surface area method by a factor of 1.5~2.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2002-299
Abstract ( 1198 )   PDF (294KB) ( 976 )
The stress-strain relationship under simple compression was derived according to the theory of Hertz, using the principle of virtual work for an assembly of mono-size spheres with regular packing, and the results were compared with those by the discrete element simulation with the code TRUBAL developed by Thornton. A good agreement between both results was shown. Further simulation for an assembly of mono-size spheres with a random packing was carried out, and a fitting expression of stress-strain relationship for the random packing was proposed.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2002-423
Abstract ( 1152 )   PDF (572KB) ( 777 )
The developments in thrust measuring techniques for the micro-thrusters are reviewed. Some typical thrust-stands are presented and discussed in detail to illustrate the principles of the impulse and average thrust measurement. In this paper, the resolution, uncertainty and thrust range of each thrust-stand are given. This may be helpful for the future thrust-stand design and studies for micro thrusters.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2003-026
Abstract ( 1457 )   PDF (753KB) ( 955 )
The linear and approximate non-linear as well as finite deformation theory of beam, plate and shell are compared. The finite rotation theory is introduced. It is pointed out that by using the finite deformation theory to solve the beam, plate and shell problems, the high efficiency and high precision can be achieved.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2001-451
Abstract ( 923 )   PDF (170KB) ( 572 )
The AR model used to analyze driving response signal is constructed. By the method, the degummed damage in alveolate composite structures is measured. Experiments on the method show that AR model spectrum has the advantage of heving a continuous smooth curve, by which the damage factor can easily be obtained. It will find applications in the quantitative analysis of active monitoring signals.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2001-461
Abstract ( 1121 )   PDF (168KB) ( 599 )
On the basis of the fundamental assumptions for the planar steel structures with semi-rigid connections and the typical stiffness equations of the framed element, the generalized elastic computational model of the planar steel structures, of which the arbitrary connection stiffness can be assumed at the ends of each element, is put forward with mathematical derivations. With the parameters associated with the semi-rigid connections considered in this model taking special values, the model can easily degenerate into two of the idealizations: fully rigid and pinned. The model presented here can also be used in a static analysis of general structures with semi-rigid connections and mixed connections.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2001-496
Abstract ( 988 )   PDF (212KB) ( 468 )
The perturbation theory is used to solve a nonlinear fluid-solid coupling seepage flow problem, where a small parameter is introduced. A numerical example is given to analyze the pore pressure along the horizontal distance at different saturation $s$ and time $t$. The theoretical evidence is provided for the relation of pressure-saturation-permeability. Furthermore, a reliable analysis method is offered to solve the nonlinear partial differential equations.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2001-498
Abstract ( 1438 )   PDF (324KB) ( 1880 )
Quasi-static collapse simulations of thin-wall-tubes are performed with Ls-Dyna code. To reduce the computational time, the speed of quasi-static loading is increased. Studies are conducted with different loading speeds. A range of the load speed used for the simulation is specified. This method is compared with Mass Scaling method integrated into Ls-Dyna.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2001-503
Abstract ( 1722 )   PDF (202KB) ( 752 )
The difference scheme of torsion problem of a bar with a sector cross-section under the polar coordinate system is derived. With Mathcad software, using the Successive over Relaxation Method, the difference values of the torsion stress function are determined; with the compound two-dimensional Simpson integral formula, the torsion stiffness of the sectoral cross-section is obtained; consequently the difference solution to the torsion stress is obtained. When the field angle is 2π, the third stress intensity factor at the crack tip is computed.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2001-519
Abstract ( 1019 )   PDF (301KB) ( 662 )
By use of V notched round bars with different theoretical stress concentration factors as finite element models (FEM) of tensile screw threads, stress intensity factors(SIF) of surface cracks of screw threads are calculated. A universal SIF formula on surface cracks of screw threads is proposed. In addition, by comparison of the SIF results of M22$\times$1.5 screw thread in this paper with experimental results, the effectiveness of the SIF results are shown.
2003, 25(3):  0-0.  doi:10.6052/1000-0879-2001-528
Abstract ( 1088 )   PDF (234KB) ( 562 )
Based on the method of wave transfer matrix, the elastic wave and vibration localization in disordered periodic structures is studied. A general formulation of the wave transfer matrix is presented, and the localization factors of ordered and disordered periodic structures are, respectively, calculated and discussed by using the method of singular-value decomposition. The method in this paper for solving the problem of the wave and vibration localization in periodic structures can be used in the optimization of this kind of structures.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2001-536
Abstract ( 802 )
Axially compressed members with non-uniform section, non-linear material and stress historical difference are studied theoretically and experimentally. The result shows that the ultimate load of a member is not equal to the summation of the respective ultimate loads of different parts on the section. Furthermore, the ultimate load and the failure location of the section vary with the stress-strain relations and initial stress differences of the materials on the section.
Education Study
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2002-012
Abstract ( 1137 )   PDF (241KB) ( 704 )
A three-dimensional stress and deformation analysis has been carried out, using the structural module of the finite element analysis software ANSYS. The strains at some points of the structure are measured and the results are found to be in agreement with the calculation.
Application study
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2002-039
Abstract ( 1091 )   PDF (290KB) ( 467 )
Damage mechanics method is applied to study fatigue problems of metallic structure members. Using the micro-structural mechanical model, the anisotropic damage coupled constitutive relations and finite element-additional loading method are established. Fatigue crack formation and propagation lives of structural members are predicted with the damage increment as the step length. Total lives of typical notched bars made of 30CrMnSiNi2A are estimated. The results show that the agreements between theoretical S-N curves and experimental ones are very good. This method requires not much of CPU time and can be applied to engineering practice in estimating lives and designing against fatigue.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2002-047
Abstract ( 893 )   PDF (193KB) ( 467 )
In order to reduce the structural drift stiffness and weaken the seismic response of structures under a strong earthquake, a reinforced concrete shearwall with vertical seams has been designed. Based on its behavior under the horizontal loads, the model of calculating its drift stiffness and the corresponding formulae are established. The results obtained from the model were found to agree well with the experimental results.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2002-070
Abstract ( 1039 )   PDF (240KB) ( 760 )
The approach, in which the flexible connection of joint of beam and column of steel frames is considered. The method is suitable for analyzing steel frames-reinforced concrete shear wall mixed structure subject to a horizontal load. The inter-story drift stiffness is derived.
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2002-108
Abstract ( 1035 )   PDF (175KB) ( 449 )
According to the theory of thermodynamics, we discuss the temperature property of soil suction for unsaturated soils. It is found that the soil suction for unsaturated soils, in a general case, decreases linearly with the increase of the temperature.
Around the mechanics
2003, 25(3):  0-0.  doi:10.6052/1000-0992-2002-192
Abstract ( 1367 )   PDF (155KB) ( 705 )
Dice is a commonly used tool for gambling. The gravitational center of a dice may deviate its geometrical center, if the dice is filled with lead. The dice can be treated as a rigid body, and the process of dice throwing can be described as the dynamics of a free body falling down and bounce back off the table. For a dice filled with lead, we calculate the probability of its downward side on the table.