Based on the mechanical properties and porous flow parameters of low permeability reservoir,an optimal re-fracturing timing model considering solid-fluid coupling in anisotropic formation was established,and the concept of equal stress point was proposed.

The result of the effective strain and the effective stresss in cavity die circular section is caculated by simulating the cup drawing in different states cosidering strain, stress and thickness changes.

Through FEM numerical simulation of flanging process which was carried out with ABAQUS software,the cognition that flanging process can be divided into 4 stages,the dynamic process of flanging,the method of computing for the prepared hole-diameter,the material thickness transformation of deformation area and the characteristic of effective stress distribution,etc.

The effective strain and effective stress are introduced under the condition of axial symmetry.

The mechanism of shoulder and bead seperations is primarily analysed in terms of the maximum shear strain,equal value stress,equal value strain and strain energy density with a 3D non linear FEA analysis software special for tire developed by Haerbin University of Technology,and the potential measures for improving the tire enduranc.

Simulation on equivalent stress in soldered joints of QFP devices with different leads;

Expression on equivalent stress and equivalent strain of wall rock state of tunnel;

Simplified calculation on equivalent stress of vortex dedendum under the effect of uniform internal pressure;

Study on transforming of principal stresses in constant stress ratio plane strain tests;

Three-modulus incremental nonlinear model of rockfill under paths of constant stress ratio;

Four moduli incremental nonlinear model of rockfill under the path of constant stress ratio

Research on simulation calculation method for randomness of cracks within equal stress zone of concrete members;