FINITE-ELEMENT EVALUATION OF FREE-EDGE SINGULAR STRESS-FIELDS IN ANISOTROPIC MATERIALS

A finite element formulation based on the work of Yamada and Okumura(1 4) is presented to determine the order of singularity and angular vari ation of the stress and displacement fields surrounding a singular poi nt on a free edge of anisotropic materials. Emphasis is placed on the computational aspects of this method when applied to configurations in cluding fully bonded multi-material junctions intersecting a free edge as well as materials containing cracks intersecting a free edge. The study shows that the singularity of the three-dimensional stress field may be accurately determined with a relatively small number of elemen ts only when a proper level of numerical integration is used. The meth od is applied to isotropic and orthotropic materials with a crack inte rsecting a free edge and an anisotropic three-material junction inters ecting a free edge. The efficiency and accuracy of the method indicate s it could be used to develop a numerical solution for the singular fi eld that could in turn be used to create free-edge enriched finite ele ments.