AN EXTENDED EQUIVALENT DOMAIN INTEGRAL METHOD FOR MIXED-MODE FRACTUREPROBLEMS BY THE P-VERSION OF FEM

A new path-independent contour integral formula is presented to estima te the crack-tip integral parameter, J-value, for two-dimensional crac ked elastic bodies which may quantify the severity of the crack-tip st ress fields. The conventional J-integral method based on a line integr al has been converted to an equivalent area or domain integral (EDI) b y the divergence theorem. It is noted that the EDI method is very attr active because all the quantities necessary for computation of domain integrals are readily available in a finite element analysis. The deta ils and its implementation are extended to the p-version FE model with hierarchic elements using integrals of Legendre polynomials. By decom posing the displacement field obtained from the p-version finite eleme nt analysis into symmetric and antisymmetric displacement fields with respect to the crack line, the Mode-I and Mode-II non-dimensional stre ss intensity factors can be determined by using the decomposition meth od. The example problems for validating the proposed techniques are ce ntrally oblique cracked plates under tensile loading. The numerical re sults associated with the variation of oblique angles show very good a greement with the existing solutions. Also, the selective distribution of polynomial orders and the corner elements for automatic mesh gener ation are applied to improve the numerical solution in this paper. (C) 1998 John Wiley & Sons, Ltd.