A computation procedure for the elasto-plastic finite element analysis of crack propagation problems

A secant based relaxation method, proposed by the present author, for improving the over-all performances of the modified Newton-Raphson iteration in solving nonlinear structural problems was used to construct a computation procedure for the finite element prediction of elasto-plastic crack propagation behaviour existing in cracked structure subjected to certain type of increasing external load. The growth of crack was achieved by releasing the internal forces of certain subregions in which stress was detected to have reached the fracture level based on the fracture criterion of maximum principal stress and maximum shear stress. In this computation procedure, the solution system is kept unchanged through the whole computation process, though the boundary condition does change along with the growth of crack line. (from author's abstract)