Computational methods for the dynamic response of cracked specimens.

摘要

This thesis describes some new methods for the numerical analysis of cracks, ways of increasing their accuracy and speed, and methods for self-contact.; The Element Free Galerkin (EFG) method is a mesh-free method in which the approximant is constructed from a set of nodes and a description of the boundary. A contact algorithm, an elasto-viscoplastic model to capture shear band development, and a new variable crack-tip velocity scheme are added to EFG.; A promising new computational method, the extrinsic enrichment of regular finite elements, is developed for dynamic problems. The eXtended Finite Element Method (X-FEM) can accurately model cracks placed at arbitrary angles within the finite element mesh. Dynamic X-FEM is formulated and applied to one and two dimensional problems.; Finally, a means of keeping a mesh refined in the region of a transient signal is presented. The method, called hyperbolic h-adaptivity, refines finite elements h-adaptively before the signal arrives, thus avoiding interpolation errors and time-step recalculation. The method is applied to several signals and geometries.