Fatigue Life of Graphite/Epoxy Laminates Subjected to Tension-Compression Loadings

A recent two-parameter fatigue model, aimed at the predictionof the fatigue behaviour of composite materials, was applied to fatigueresults available in the literature, concerning graphite/epoxy laminatessubjected to tension-compression loadings. It was found that the model,successfully applied in the case of tension-tension andcompression-compression fatigue, also works when the sign of stress isreversed during fatigue. However, the constants appearing in theproposed formula must be evaluated anew when the loading mode changesfrom pure tension to tension-compression. The probability of failure infatigue is predicted with reasonable accuracy by the model, which isvery conservative in calculating the residual strength after a givennumber of cycles.