Finite element crack-tip meshing criteria in linear elastic crack problems

Finite element meshing techniques for determination of linear elastic crack tip stress intensity factors (KI) are presented. Displacement extrapolation method is used to calculate stress intensity factors. The finite element analyses results are obtained using various type of meshes at the near-crack-tip which consist of quadratic and collapsed triangular isoparametric elements with distorted midside nodes and are compared to known solution. This paper shows that excellent results are obtained through the use of triangular elements both at the first and second layer of the crack tip even when very few elements are used. The effects of the singular elements size both in circumferential and radial directions are presented. The recommended size of the elements neighbouring to the singular elements are also provided. (author)