A Study on Edge Protection Against Delamination for Composite Laminates : 1st Report, The Effects of Edge Shapes on Stress Singularities for Cross-ply Laminates

Abstract

Edge delamination is one of the major factors that determine the fatigue strength of composite laminates and it is attributed to the existence of highly intensified interlaminar stresses in the neighborhood of the free edge. In order to develop an efficient method to prevent edge delamination, in this paper, the effects of the geometrical shape of the free edge on r^σ stress singularity are discussed for cross-ply laminates. It is shown that the order to stress singularity can be controlled by varying the geometrical shape of the free edge and that the singularity disappears for some combinations of the angles which the edge surfaces of the two neighboring layers make with respect to their interface. In the case of multi-layer laminates, it is also possible to eliminate stress singularity completely or to reduce its order drastically at all interfaces by slanting the entire free edge at an appropriate angle.