Scaling effects in notched carbon fibre/epoxy composites loaded in compression

Abstract

The aim of the work was to develop an understanding of the failure mechanisms controlling the strength of composites of different dimensions and hence to be able to predict size effects in composite structures without resorting to empirical laws. Adequate models do not currently exist, and extensive testing is necessary, which is very costly. The ability to predict the effect of size on strength would be a major step forward, which would reduce costs and encourage the more widespread usage of these materials in the aerospace and other industries. In this article the effects of scaling (specimen size) on the strength of notched laminates are presented. The most important variables have been identified as hole (notch) size, ply and laminate thickness. Manufacturing defects and specimen design can also lead to premature failures, especially in unnotched laminates, but in laminates with an open hole are of less significance, since the notch dominates the fracture. The compressive strength results are compared to data obtained for the same composite system and laminate stacking sequences loaded in uniaxial tension.