Investigation on propagation characteristics of acoustic emission waves in composite heterogeneous structures

Objective This study in this paper aims to investigate the impacts of acoustic emission (AE) signals on the propagation characteristics of composite hetero-structures.

Methods First, the calculation procedure of dispersion curves is developed based on a semi-analytical finite element method to calculate the group velocity dispersion curves of AE waves in composite panels. Then, ABAQUS is used to establish the finite element model and to investigate the dispersion characteristics and attenuation characteristics of AE signals in the composite structure. Finally, the time-frequency characteristics and mode conversion of AE signals in the T-shaped composite hetero-structure are analyzed combined with wavelet transform and modal acoustic emission theory.

Results The results show that the attenuation of AE signals is related to the propagation distance and propagation direction of signals, and the signal will be significantly attenuated when passing through the hetero-structure interface. The interaction between AE signals and hetero-structure will produce complex propagation phenomena, including T-shaped transformation and modal conversion. The signal strength of the reflected signal is the strongest in the T-shaped transformation of the AE signal, and the signal strengths of the transmitted signals across the structure and the transmitted signals through the 90° corner of the structure are comparable.

Conclusion This work in this paper quantified the scattering characteristics of AE signals using reflection and transmission coefficients, providing a theoretical reference for AE monitoring of marine structures.