Guided wave based online monitoring of composites

Composite structures find wide applications in aerospace & automotive industries, often with complex features. To detect artifacts reliably in these structures ultrasonic guided wave technology has been found promising. Guided waves have low propagation losses in uncoated media and typically operate at lower frequencies as compared to conventional ultrasonic testing. Due to their through-thickness modal structure, ultrasonic guided waves find potential application in studying defects and disbonds in the inter-laminar region of composite plates. However, the typical current implementations of guided waves consist of a set of transducers bonded to the composite structure. This is prone to difficulties such as disbonding of sensors from the surface of the structure over a period of time. This paper explores an alternative method of guided wave health monitoring of composite plates making use of their internal structure. 2D Finite Element Simulations have been used to generate ultrasonic waves and to demonstrate the approach with a simplified delamination model. We show that, the mechanism allows us to detect, assess and monitor the growth of delamination/crack.