Experimental Verification of Lamb Wave Identification of Delamination Defects through Covariance of Energy Change

Abstract

Delamination is currently a difficultly-detectable form of damage in composite laminate materials. This paper experimentally validates an innovative method that more easily detects delamination damage within composite materials through the covariance of energy change. Lamb waves were introduced and recorded through an actuator and sensors made of piezoelectric material. The data was then analyzed through the Fast Fourier Transform (FFT). Using the data from FFT, the idea of covariance of energy change was suggested to correlate with defect characteristics. By comparing the covariance of energy change in beams with different delamination sizes and depths, correlations between the covariance of energy loss and defect characteristics were developed. With these correlations, the severity of these damages was quantified.