Because the traditional parameters evaluation has drawbacks and there are many parameters in the visco elastic plastic unified constitutive model, a parameters correlation evaluation method is drawn out in this paper.

The history and quality of the Unified Constitutive Model theory are stated in the thesis.

In order to rnodify the description to the rate dependent mechanical behaviour of ductile materials,in this paper, a new unified viscoplastic constitutive model posspssing overstress characteristics was suggested.

Nonlinear constitutive model research on concrete considering temperature effect;

Rheological stress constitutive model of medium carbon constructional quality steels under thermal tension;

Program implementation of 3-D expanded constitutive model of Cosserat medium for laminated salt rock;

The constitutive data for the new model is fitted and the simple shearing experiment is utilized to prove the feasibility of the constitutive equation produced in this paper.

Furthermore a constitutive equation using updated Fields and Backofen equation is established.

The main considerations include the following cases: firstly,the microforming-technics system and the test results in the micro-punching,micro-extrusion,micro-deep-drawing and superplastical microforming,secondly,the phenomena and the mechanism of micro-size effect in the microforming,and thirdly,a review on the developed or developing micro-size constitutive equation .

The 3D images of geotechnical constitutive models in the stress space;

Study of elastoplastic neural network constitutive models for sand under different stress paths;

Advances on the research of dynamic constitutive models of saturated soils;