Investigation of Stresses in the Vicinity of Crack Tip through the Three Dimensional Elastic Finite Element Analysis

The object of this paper is to find the stress distributions through the thickness direction by using the three dimensional elastic finite element method (3-D FEM). First, the authors propose the new procedure for the FEM calculation without assembling the stiffness matrix [K], because the 3-D FEM requires the large storage core for [K]. Furthermore, the deflection vectors obtained by the two dimensional FEM are used as the initial values for the iteration method, which is programed in the 3-D FEM. In consequence, it is clear that the present method is able to analyse the problem with a large number of nodal points within the storage core and to expect the good convergence of solutions within a few number of iterations. Finally, the stress distribution and the stress intensity factor K_1 through the thickness direction are evaluated by using the present FEM program. At the center of thickness, the thickness directional stress is effected on the plate thickness B, but the other stresses and K_1 are almost independent of B.