Impact of manufacturing flaw on fatigue damage development and on stiffness variation in woven composite plates

Abstract

Under dynamic loading conditions, damage in a plain weave Carbon Fiber Reinforced Polymer (CFRP) composite is a complex and multiscale process especially in the presence of a manufacturing flaw. In this context, this paper investigates the impact of an inserted flaw on the damage scenario and stiffness degradation over fatigue life. To achieve this objective, a full three-dimensional Finite Element Model (FEM) is developed to evaluate the stress distribution induced by the local defect. Fatigue tests are then performed on two configurations with and without inserted flaws with continuous monitoring by NDT techniques. The Acoustic Emission (AE) method is used for damage quantification and source localization while Digital Image Correlation (DIC) and Air-Coupled Ultrasonics (ACU) are applied to evaluate the stiffness degradation. The cross results obtained using the three monitoring techniques provide an insight into the damage process and stiffness degradation in woven composite with a simulated manufacturing flaw.