Open Access Open Access  Restricted Access Subscription or Fee Access

Characterization of CFRP Laminates: Linear and Nonlinear Acoustic Measurements of As-Fabricated Materials

D. BARNARD, S. CHAKRAPANI, A. SUBRAMANIAN, L. BOND

Abstract


Changes to the microstructure of a composite laminate during the early stages of fatigue are quite subtle, particularly with respect to the capabilities of most nondestructive evaluation methods. Additionally, the nominal variation of microstructure within the laminate and this variations effect on nondestructive evaluation signals further limits the sensitivity of any given method to fatigue damage. Here we report on the level of variation in ultrasonic response of asfabricated CFRP laminate samples, in unidirectional, cross-ply and quasi-isotropic layup configurations. In additional to the standard immersion back wall pulse echo amplitude c-scans, we show results of precision attenuation and backscatter amplitude measurements in c-scan formats, as well as nonlinear ultrasonic resonance spectroscopy (NRUS) results. This material was based upon work performed at Iowa State University and supported by the US Army Research Office.

Full Text:

PDF