STRESS INTENSITY FACTORS BY WEIGHT FUNCTION-METHOD FOR CRACKED COMPOSITE LAMINATES

A finite element method with virtual crack extension technique is employed to find the weight function of the stress intensity factor for a cracked composite laminate. Since the weight function is load independent, once it is obtained, the stress intensity factor of a cracked laminate subjected to an arbitrary external loading system can be calculated efficiently by performing the integration of the work-like product of the load and the corresponding weight function over the area where the load is applied. If the weight function for a specific cracked laminate is known, the stress intensity factor for another geometrically dissimilar cracked laminate may also be calculated by using that given weight function. The procedure is to isolate a sub-plate from the whole laminate. This sub-plate is geometrically identical or similar to the plate with known weight function. Then the stress intensity factor of the original composite laminate is determined by performing the same integration of the work-like product of the given weight function and the self-equilibrium forces acting on the sub-plate. Several examples are shown to demonstrate the accuracy and efficiency of this powerful method.