Study of ultrasonic guided wave interaction with core crush damage for NDE of a honeycomb composite sandwich panel

Abstract

Honeycomb composite sandwich structures are extensively used for the manufacturing of many different components of aerospace, automobiles, wind turbine blades, and marine ship hull structures. Despite its widespread use and advantages, the honeycomb core is frequently damaged during production and operation, even if the damage is not visible on the face sheet. In this study, an ultrasonic guided wave (GW) propagation technique is utilised for robust and reliable non-destructive evaluation of a honeycomb composite sandwich panel (HCSP) in the presence of core crush damage. A 2D semi-analytical model was developed to understand the dispersion characteristics in the HCSP and to identify various modes of GW propagation in the signals. Extensive numerical simulations are carried out using ABAQUS, to study the guided wave interaction with core crush damage. For this purpose, two numerical models were considered (a realistic model with both crushed core and cavity, and a simplified model that only comprises of the cavity) and experimentally validated using a contact-type transducer. It is found that presence of core crush damage in a HCSP increases the amplitude and group velocity of the primary anti-symmetric mode, and this characteristic has been used for localisation of the core crush region in the HCSP. Finally, a damage detection algorithm using signal difference coefficient is presented for successful localization of the core crush region within a square monitoring area. Unlike other studies reported in literature, we demonstrate the utility of the simplified numerical model for studying GW interactions with core crush defect, and experimentally validate the non-destructive evaluation (NDE) technique to localize core crush defect on an HCSP.