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

Objective This study investigates the impacts of acoustic emission (AE) signals on the propagation characteristics of composite hetero-structures.

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

Results The attenuation of AE signals is related to the propagation distance and direction of signals, in which a signal is significantly attenuated when passing through the hetero-structure interface. The interaction between AE signals and the hetero-structure will produce complex propagation phenomena including T-shaped transformation and modal conversion. The signal strength of the reflected signal is 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 paper quantifies the scattering characteristics of AE signals using reflection and transmission coefficients, thereby providing theoretical references for the AE monitoring of marine structures.