Statistical Fatigue of Graphite/Epoxy Angle-Ply Laminates in Shear1

Abstract

A three-parameter fatigue and residual strength degradation model has been proposed to predict statistically the fatigue behavior of composite laminae under axial shear loadings. The fatigue behavior includes the fa tigue life and the fatigue damage expressed in terms of the residual strength degradation. An experimental test program using graphite/epoxy [±45°] _2s laminates has been conducted to generate statistically meaningful data in order to examine the validity of the theoretical model. It is shown that the correlation between the theoretical predictions and the test results on the statistical distributions of the fatigue life and the residual strength is excel lent. Test results on the shear modulus degradation are also presented and discussed in detail in order to provide insight for the establishment of a shear modulus degradation model.