Sensing Applied Load and Damage Effects in Composites with Nondestructive Techniques

Abstract : Composite materials are desirable for many aerospace applications but pose challenges due to their complicated damage mechanics. Implementing a structural health monitoring (SHM) strategy for composite structures is one approach for assessing the health or damage state in real time. Application of SHM requires not only the ability to localize, classify, and quantify damage, but also compensate for changing environmental and operating conditions. One such problem is compensating for the effects of applied load on a composite structure to correctly estimate damage. To study the effects of applied load, composite coupons were tested in static and fatigue loading, gathering data in various damage and loading states with multiple nondestructive evaluation (NDE) techniques. Evaluation using piezoelectrically induced guided waves, acoustic emission, thermography, and X-ray imaging were compared and correlated. This report summarizes experimental setups involving the various NDE methods and technics and provide results on the effects of load and damage in the received ultrasonic signals.