Explore the Influence of CFRP Surface Woven Fabric on Nonlinear Acoustic Detection

While woven fabric is integral to carbon fiber reinforced polymer (CFRP) plates manufacturing, there has been a notable absence of research focused on the nonlinear detection of CFRP woven fabric. This article employs nonlinear acoustic methods to assess the response of CFRP plates, including unwoven, twill weave, and plain weave structures, to surface microcrack damage. A set of air-coupled nonlinear ultrasonic automatic detection systems was designed to acquire the amplitudes of the fundamental frequency and the second harmonic in the received signal, enabling the calculation of relative nonlinear parameters. Furthermore, the nonlinear cumulative effect was verified by varying the propagation distance. The experimental results highlight the significant influence of woven fabric on the outcomes of nonlinear acoustic testing. Specifically, the nonlinear response of unwoven CFRP to microcracks is the most pronounced, followed by twill weave CFRP plates. Notably, plain weave CFRP can significantly hinder the effectiveness of nonlinear acoustic detection. In cases where CFRP plates are loaded with such woven fabric, there is a potential for lower relative nonlinear parameters when damaged compared to their healthy state.