Propagation and scattering of guided waves in composite plates with defects

Abstract

Failure in aerospace composites owing to low-velocity impact raises a significant maintenance concern because it can lead to invisible damage. For the aerospace industry, such defects pose a potential danger to the structural integrity of aircraft. This in turn jeopardises passenger safety and incurs high repair costs. Hence, it is important to efficiently monitor composite structures during the service life. In this study, the potential of low-frequency guided ultrasonic waves for health monitoring in laminated composite plates is investigated. This study focuses on the use of the first antisymmetric guided wave mode (A0). The first part of this study is to investigate the propagation of the A0 mode in three different undamaged composite plates experimentally. The dispersive and anisotropic behaviour are in agreement with the results of finite element simulations and semi-analytical analysis. The final part of this study presents the scattering of guided waves at the impact damage using a non-contact laser interferometer. Significant scattering activities were observed and the impact damage size can be estimated to be about 10 × 25 mm. In conclusion, these results demonstrate the potential of guided ultrasonic waves for the inspection of aerospace composite structures.