Extracting Mode Converted Guided Wave Response due to Delamination using Embedded Thin Film Sensors

Delamination is the most common type of damage that can occur in a composite structure at a very early stage of its operation. Detection, localization and classification of delamination parameters in composite laminates assist in determining the operating condition of the structure. Such a task, especially involving global localization on the structure and local localization along the thickness of the laminate is difficult using guided waves that are inherently multimodal leading to complicated mixed mode response of transducers. This paper proposes the use of embedded thin film sensors to decouple the response due to each wave mode enabling easy interpretation of the signals for damage detection. Delamination damage has been considered and the strength of reflected guided wave modes has been studied in the purview of delamination localization along with the thickness. The variation of mode conversion strength for fundamental and higher order wave modes further provides additional data to determine the delamination parameters.