一方向CFRP板を伝搬するラム波の減衰の周波数及び伝搬方向依存性の計測と周波数スペクトルの補正

抄録

Damage in CFRP has been classified mainly based on frequency-domain features of the waveform using the AE method. On the other hand, AE waves in a CFRP plate propagate as Lamb waves and attenuate and scatter as they propagate. The attenuation and scattering depend on the mode of Lamb waves, frequency, and propagation direction. Therefore, features of AE waveforms change due to attenuation and scattering, making it difficult to classify fracture modes. In this study, the dependence of the attenuation on the frequency, and propagation direction for symmetric and anti-symmetric modes of Lamb waves in a unidirectional CFRP plate was measured to compensate frequency spectra of Lamb waves at different propagation lengths. It was confirmed that the anti-symmetric(A) mode Lamb wave has larger attenuation than the symmetric(S) mode, and the S-mode Lamb wave has a stronger dependence on the propagation direction than the A-mode. Based on the measured attenuation coefficients, we attempted to compensate for the frequency spectra of the waveforms detected by two piezoelectric-type AE sensors with different diameters. The compensation could be performed for the small sensor only.