Fatigue life prediction for impacted carbon/epoxy laminates under 2-stage loading

The paper presents the fatigue behavior of carbon/epoxy laminates with impact-induced damage under 2-stage tensile loading. To describe this behavior, the strength reduction concept is introduced herein, based on Broutman’s model under 3-stage loading. By using this concept and fatigue behavior of the unimpacted laminates, a model is derived to predict the residual life of the impacted laminates and then verified through fatigue tests on the impacted laminates under 2-stage loading. Also, a new reliability method is established to describe the variation of cumulative damage behavior and fatigue life.