The Analysis About The Stress Singularities Of Three-Dimensional Interface Edge And The Interface Fracture

With the improving the requirements of materials in modern works constantly, more and more new materials are used, and combination materials as one kind of new material, are very extensive used in various fields of engineering. In practice, the combination material damage often occurs in the interface edge region, and the destruction of the combination materials is more complex than the isotropic material. So, the study of the stress singularity of interface edge and the destruction at the interface or near the interface edge is very important.The main research of this thesis is about the mechanical problem of interface structure composed of two different isotropic materials, which is in elastic range and under static loads.Firstly, on the basis of the basic theory of interface mechanics, in order to get the stress field and displacement field, FEM has been used to do numerical simulation, and then the singularity exponents of interface edge are separated to get the each singularity exponent of interface edge. The influence of material matching combination, geometric composition and the other factors to interface edge stress singularity has been talked about, and thesis shows the transportation of the interface stress wave under impact loading simply. The study shows that when the poisson rate is the same, the greater the diference of the two material Young’s modulus is, the more serious the stress singularity is; when the Young’s modulus rate is the same, the change of the poisson can make the stress singularity change; and the smaller the3D interface edge joint angle is, the more serious the stress singularity is.Secondly, in order to study the destruction of combination materials, the fracture in the interface or near the interface has been talked about. The stress field and displacement field is got by the means of numerical simulation, which shows the SIFs always couples together. The straight-line extrapolation method has been used to get the stress intensity factors and strain energy release rate in2D problem; Because of the particularity of three-dimension problem, the thesis cannot only talk about plane strain probem. For3D problem, the straight-line extrapolation method and M integral have been used to get the stress intensity factors and strain energy release rate, and then the contrast of extrapolation method and M integral in accuracy has been shown in this thesis. At the same time, the particularity of the crack near the interface has been shown; and the calculated formulas of the stress intensity factors near the interface edge have been given.