Mixed mode fracture analysis of rectilinear anisotropic plates by high order finite elements

A singular finite element is developed for direct calculation of combined modes I and II stress intensity factors for planar rectilinear anisotropic structures subject to arbitrary loading. Twelve‐node conventional elements are used in conjunction with a linear elastic fracture mechanics enrichment of the same element which is formed into a four‐element macro‐element. Example problems show this formulation to be exceptionally accurate and results are presented for a variety of modern fibre‐reinforced composites in simple mode I extension and in mixed mode I and II situations. In addition, it is shown that the meshes for accurate results are relatively coarse and thus calculations are quite economical.