In this thesis, the structrure differences between ordinary V waffle fin dies and double bridge fin dies have been introduced, and the technological process and characteristics of double bridge dies have been analyzed.

Based on the finite element method and periodic boundary conditions,a method to analyze the compressive strength of stitched laminates was established,which adopted a bridging model and maximum stress criteria to predict the development of damage and obtain the compressive strength.

Nonlinear characteristic of matrix material is considered in the bridging model constitutive theory of composite materials.

The method adopted bridging model and maximum stress criteria to predict the development of damage and obtain the shear strength.

Research on modifying Cam-clay model considering shear deformation;

The Cam-clay model has widely been used in the last decades which described the main features of soil elastic-plastic stress-strain relationship.

In consideration of the fact that the Cam-Clay model is incapable of reflecting the deformation characteristics of initially anisotropic soil,and that the Ohta-Sekiguchi model can reflect the initial anisotropy of soil to some extent by adoption of a new stress ratio,the two models are modified by readjustment of the yielding locus and hardening axis in p-q plane.

Comparison and analysis for the shear strengh calculation of reinforced concrete bridge pier model;