A new ultimate strength model of notched composite laminates - including the effects of matrix failure

A new ultimate strength model is developed to predict the final failure, with the influence of matrix failure, of notched cross-ply laminates. The present model is based on the estimation of the local stresses and the redistribution of the local stresses in the critical damage zones around the notches. The new ultimate strength model can be stated as: when the local stresses in the critical-load-carrying elements reach their failure strength, the critical-load-carrying element will fail and the ultimate failure will occur. In order to estimate the local stress concentration in the critical damage zones, a method is developed and applied to decompose the local stress concentration into several parts, e.g., the geometrical contribution, the stacking-ratio contribution, and the damage contribution. Combined with a single numerical simulation for a notched laminate, the damage-dependent stress concentration of the laminate can be established for different notches and it is then utilized to predict the ultimate strength of notched laminates with different notches. The applications of this method show that the model prediction agrees with the experimental observations satisfactorily. Keywords: ultimate strength, notched laminates, notch-induced splits, stress concentration, notch size effects.