Damage Identification and Assessment in Tapered Sandwich Structures Using Guided Waves

Abstract

Damage detection using guided waves in the inspection of tapered sandwich structures with high density foam core (Dyvinicell HP100) is investigated. Characterisation of the fundamental symmetric and anti-symmetric Lamb wave modes is carried out in terms of their velocity and magnitude variation as they encounter a change in the thickness of a composite sandwich plate, aiming at optimising the mode selection to improve the capability and increase the sensitivity of guided waves in inspection of tapered sandwich structures. In addition, an imaging algorithm based on time reversal is developed to detect multiple debonding and artificial damage in tapered sandwich panels based guided waves from an active sensor network. The correlation coefficients between the original and reconstructed time reversal signals are calculated to define a damage index for individual sensing paths, which are used later in the fusion process, identifying the presence of damage in the monitoring area enclosed by the active sensor network. The results confirm that the incident wave signals and their reconstructed time-reversed counterparts can be used to accurately detect the debonding/damage in tapered sandwich structures.