Feasibility Analysis of Various Sensing Methods for Nondestructive Testing of Composites

Abstract

Guided ultrasonic wave-based methods are promising for detecting defects over long ranges in isotropic and composite materials. The technology has seen a lot of attention in the research community over the past decades, and many analytical and numerical methods have been developed to describe different aspects of wave propagation and scattering phenomena. However, very little research was geared towards the physical implementation in practical applications. Hence, in this study, the detectability of defects in composite materials (delaminations and core-skin disbonds) with different sensor technologies is investigated. To induce and record scattered guided ultrasonic waves, broadband contact transducers, air-coupled transducers and a laser Doppler vibrometer are used. It is shown that the thickness of typical sandwich panels used in aerospace industry and the non-homogeneous nature of the honeycomb core material make precise localization and identification of defects challenging, in particular in non-contact scenarios.