Failure analysis for composite laminates

A discussion of the tensor polynomial failure criterion is presented together with a description of a biaxial compression test procedure used in the evaluation of the interaction strength parameters. In addition, a formulation for predicting the fatigue life of laminates is given based on the experimental evaluation of fatigue functions which are also utilized in a form of the tensor polynomial failure criterion as well. Experimental results are provided to compare with the fatigue life predictions and to demonstrate the effect of flaws and environment. Both bond-line defects in sandwich beam construction and inter-laminar disbond flaws are studied. Up to present, compressive strength test data have been obtained for ambient and elevated temperature, moisture-saturated conditions, including results from thermal-spike cycling simulating supersonic flight.