Quantifying the orthotropic damage tensor for composites undergoing damage-induced anisotropy using ultrasonic investigations

We quantify the evolution of the general fourth order damage tensor for initially orthotropic composites undergoing damage-induced anisotropy using ultrasonic investigations. Two of the most challenging problems which arise in continuum damage mechanics are firstly the selection of variables to describe the internal damage and secondly the difficulty in modelling materials with significant initial anisotropy such as composites. This research helps advance models of anisotropic damage to overcome both these challenges. We demonstrate how to identify the directionality and magnitude of the introduced damage using experimental ultrasonic measurements of damaged elastic moduli for initially anisotropic materials. This analysis provides a robust way to validate and advance models based on continuum damage mechanics and develop phenomenological models of anisotropic damage evolution for initially orthotropic materials.