The virtual displacement principle of elasto_plastic damage mechanics is presented.

It is verified experimentally with samples that the plastic damage in 45 # steel can be evaluated with the variation of the ultrasonic attenuation coefficient, as it is shown that an increase of the load leads to an increase of the area of the crack tip region extending into the detecting region and accordingly an increase of the ultrasonic attenuation coefficient with regularity.

Considering the inner micro plastic damage ,using the finite element method (the computational cell model) and compiling the program to get parameters controlled ductile crack growth, the process of ductile fracture was simulated.

The laser diffraction technigue is used to detect the surface plastic damage in 30CrMnSiA plates.

But the concrete damage plasticity model is greatly limited when beam elements are used and it can t represent the complicated response of the beam and column with rebar and other steel strings.

Mohr-Coulomb and concrete damage plasticity model are used to describe the nonlinear properties of the soil and the concrete respectively.

Application of 3-D elastoplastic damage model with bolts to a large sized rockmass slope engineering;

Application of 3-D elastoplastic damage model with bolts in XILUODU underground power house;

Analysis of elastoplastic damage for high jointed slope of the Three Gorges Project shiplock during unloading due to excavation;

Comparison of macro-scale and meso-scale elasto-plastic damage failure in rocks;

3D numerical simulation of elasto-plastic damage and failure process of marble rock;

Furthermore,the incremental elasto-plastic damage constitutive equations and damage evolution equations were established.