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Composite materials can sustain a much higher load in inplane tension after the onset of local damage. The ultimate strength of composite laminates can be accurately predicted with finite element analysis if the proper increment is used in each step. An analysis of the appropriate nodal spacing both in the plane of the specimen and in the thickness direction has been made with particular attention to the problem of stress concentration at the free edges. The load for final catastrophic failure and the failure pattern in progressive failure both agree well with experimental results.

It is well known that the stress field at the tip of a crack in an elastic body exhibits a singularity. In this paper, a complete elastic solution for a center cracked plate loaded under uniform tension is obtained by a finite element plane-stress analysis using constant strain elements. No a priori assumptions about the form of the stress singularity are required. The numerical results are compared with the exact analytic solution. It is shown that a particular mesh arrangement in which the size of the elements decreases in a geometric series as the crack tip is approached yields stress and strain fields which are accurate over the entire plate, even at distances very close to the crack tip. The effects of changes in mesh arrangements on the accuracy of the solution are considered. The computations are carried out on the CRAY-1 computer and the advantages of vectorization are discussed for this problem.

In this paper, the finite element method is applied to a center-cracked plate subject to opening mode tensile loading. A complete elastic-plastic plane-stress solution for strain hardening materials obeying a Von Mises yield condition and Prandtl-Reuss stress-strain relations is obtained using only constant strain elements. An accurate representation of the stress-strain field even at distances very close to the crack-tip, is achieved by the use of a mesh arrangement in which the size of the elements decreases in a geometric series as the crack tip is approached. The numerical solution is compared with and used to discuss the range of validity of the well-known HRR (Hutchinson-Rice-Rosengren) crack tip solution valid for small scale yielding. The influence of different amounts of hardening and the effect of changes in the mesh arrangements are also considered. Features of the finite element algorithm which reduce the total computing time are discussed. The finite element program is executed on a CRAY-1 computer and the effect of vectorization on computational speed is discussed for this problem.