Fatigue life prediction of impacted carbon/epoxy laminates under constant amplitude loading

The purpose of the present paper is to investigate the fatigue behavior and variability of fatigue life in carbon/epoxy laminates with impact-induced damage under tensile fatigue loading. To describe the fatigue behavior of the impacted laminates, the strength reduction concept is introduced herein, based on the Broutman's model under 2-stage loading. By using this concept and fatigue behavior of the unimpacted laminates, a fatigue life prediction model for the impacted laminates is derived and then verified through the fatigue tests on the impacted laminates under constant amplitude loading. Also, to identify the fluctuation of fatigue life in the laminates, a statistical model is developed by introducing the random variable Z. The model well describes the distribution of fatigue life in laminates and its variation decreases rapidly as applied impact energy increases. (C) 2004 Elsevier Ltd. All rights reserved.