Dynamic stress intensity factors in orthotropic materials.

摘要

formulation based on a two dimensional dynamic linear elasticity approach is developed to obtain a elastodynamic solution for an orthotropic material when loadings are applied suddenly. The problem of determining the distribution of stresses in the neighborhood of plain strain constant velocity moving cracks and transient response of impact loading cracks located on a single line is examined. The medium containing the crack is a semi-infinite, specially orthotropic material. The mathematical treatment of a constant velocity crack is simplified by defining a set of coordinate axes attached to the moving crack. The general equations for the moving crack tip in specially orthotropic bodies are derived by the use of Fourier transforms and Laplace transforms in the context of a boundary value problem and in case of transient response of the crack, the use of Fourier transforms for space variables and Laplace transforms for time variables renders a general equation. In Chapter 3, two cases concerning the dynamic stress intensity factors in the steady state case will be considered. In section 3.1, tensile, and in section 3.2, shear center cracks are considered, respectively. The cracks are in a specimen of infinite length but finite width. The stress intensity factors are derived in terms of the mechanical properties of the homogeneous orthotropic material and the steady crack speed. The results are produced for a horon epoxy material with crack velocity ratio