Proper

Abstract

In the present study, we have developed a system for evaluating stress intensity factors (SIFs) of three-dimensional cracks found in materials. In general, the kind of system has to be flexible in extending its functions, and easy for ordinary engineers to use. Artificial intelligence technique was used to obtain the SIF for subsurface cracks and surface cracks existing in materials. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy theory. Nodes are generated by the new advancing front method, and ten-node quadratic tetrahedral solid elements are generated by the adaptive finite element techniques. The singular elements such that the mid-point nodes near crack front are shifted at the quarter-points, and these are automatically placed along the 3D crack front. The complete FE model is generated, and a stress analysis is performed. This system is applied to analyze cladding effect of surface cracks in materials.