Evaluation of Adhesive Interface Properties in Honeycomb Sandwich Structure Using Guided Waves

Abstract

A method is presented to evaluate the interfacial weakness of aluminium-based honeycomb sandwich structure (HSS) using Shear Horizontal (SH) guided wave. SH guided waves are sensitive to the interfacial properties since the wave particles vibration is oriented parallel to the adhesive-adherent joints. Periodic permanent magnet (PPM) electromagnetic acoustic transducers (EMATs) are used to excite and detect SH-guided waves. A semi-analytical finite element method is developed to simulate the SH wave propagation in HSS. The boundary stiffness approach is used to model the adhesive-adherent interface. The excitation parameters are chosen such that only SH0 mode is generated in the structure. The interaction of the fundamental SH0 wave mode with various defects and the different interface stiffness is analyzed. The frequency-wavenumber analysis is used to study the effect of interface stiffness on SH wave propagation. The analysis reveals that in a perfect bond, SH0 and S0 guided modes are present. The interaction of SH0 mode with the honeycomb core results in the genesis of S0 mode. Thus, the presence or absence of the S0 mode can be used as an indicator of bond quality. The findings from the FE simulation are validated against the experiment. The analysis shows a reliable non-destructive evaluation of the interface joint and classifying them as good or bad bonds.