Influence of Location and Thickness Variations on Guided Waves in Defective Carbon/Epoxy Plate

Abstract

This paper addresses the effects of plate thickness and defect location on guided wave propagation in carbon/epoxy plates. A three-dimensional (3D) finite element model (FEM) of the plate was developed using MATLAB program codes, and simulated in Abaqus/Explicit. Referring to experimental ultrasonic C-scan images, the complex impact damage was modelled with irregular-shaped delamination and through-thickness matrix cracks. The simulated results show that a slower arrival time signal and amplitude drop of guided wave captured behind the defective region can be used as an indicator of the impact damage. A largOer scattering occurred when delamination was located closer to the plate surface. The extent of scattering gets larger, especially in the direction of 345o from the excitation point. It is also observed that the impact damage can still be detected through a line scan method across the impact damage, although the wave attenuation is greater in a thicker composite plate. By investigating these factors independently, the trends of the scattered guided ultrasonic waves can be classified and perhaps will revolutionize a smart non-destructive method for composite structure in the future.