Structural state awareness of composite structures by blending passive and active acoustic-based health monitoring methods

Abstract

This study aims to demonstrate the effectiveness of blending passive and active acoustic-based health monitoring methods to impact damage diagnostics of composite structures. The structural state awareness is introduced as a term to characterize the health condition that a structure is and how this condition can be quantified by blending health monitoring techniques. To this aim, a Carbon Fiber Reinforces Polymer (CFRP) composite plate was fabricated and subjected to a simulated low-velocity impact by performing repeated quasi-static indentation tests where a loading-unloading-reloading test profile was adopted. Two Acoustic Emission (AE) broadband sensors and a network of eight piezoelectric (PZT) sensors were attached on the composite plate surface. AE (passive method) was employed during the loading and reloading phases of the indentation tests to in-situ monitor the damage initiation and progression, while scanning of the plate with Lamb waves (active method) was done to localize the damage when the structure was unloaded. The obtained results showed that the proposed blended passive and active acoustic-based method has the potential to provide useful information about the impact-induced damage in composite structures.