Acousto-ultrasonic evaluation of interlaminar strength on CFRP laminates

The acousto-ultrasonic approach is experimented on CFRP laminates. The test was organized in two modes: before the impact event and after the impact event; along longitudinal and transverse directions. Finally, the Compression after impact (CAI) test is performed on the impacted specimens to characterize its residual compressive strength. The AE descriptors loss along the longitudinal and transverse directions of the specimen are utilized to characterize the interlaminar strength of the specimen. With the help of Continuous Wavelet Transform (CWT) analysis, a hypothesis is created to discriminate the loss variation of AE descriptors to characterize the interlaminar strength of the material and the presence of damage or flaw in the material. The hypothesis holds true that the direction along which the relative loss of AE descriptors is low, has the lowest interlaminar strength. The mechanical results support the hypothesis created. With the proper channelling of acoustic signals and discrimination of data, the acousto-ultrasonic approach can be extended to characterize the interlaminar strength of the mechanical structures.