High-resolution defect imaging in laminate composites and honeycomb structures

Abstract

Carbon fiber reinforced polymer (CFRP) plates and honeycomb composite sandwich structures (HCSS) are extensively used in the aerospace industry due to their excellent strength-to-weight ratio, stiffness, and corrosion resistance. Nevertheless, these structures are susceptible to hidden damage defects such as face sheet delamination or core-sheet debonding that may appear due to impact forces or thermo-mechanical aging and can decrease these properties. GW-based structural health monitoring (SHM) system is considered as a promising solution for such structures inspection. It has been proven, that GWs can explore large areas while being sensitive to the present flaws. This paper reports on the guided waves imaging for CFRP plates and HCSS in order to localize and characterize defect. High-resolution cartography of the structure of interest is obtained by means of a baseline demanding defect-imaging algorithm. It computes and assigns a damage index value to each pixel of the cartography. A damage index value is obtained by correlating experimental to theoretical signals. While a sparse grid of piezo-electric transducers is used for GW actuation and sensing, the theoretical signals are computed by two-dimensional semi-analytical finite element (SAFE) modeling. The major advantage of this methodology is the capability to localize defects with a high degree of accuracy. Augmented reality application for SHM system is also presented. Such an application is used for SHM systems periphery and inspection results visualization.