Non-Destructive Evaluation of Disbond Size in Honeycomb Sandwich Structures Using Guided Lamb Waves: Feasibility Study

This work focuses on the characterization of a hidden macroscopic defect, specifically disbond, which may occur in sandwich panel structures used in aeronautics, using guided Lamb waves. The objective is to estimate the surface area of the detachment between the core and the face sheet of a sandwich. The S0 Lamb wave was excited using the pitch-catch configuration at a frequency of 500 kHz. A detachment with a disc-shaped surface was created for different surface sizes. The signal sparse representation process (SSR) was exploited to measure the time of arrival (TOA) of the received signals. The TOA was then evaluated as a function of a disbond size. The results revealed, on one hand, the effectiveness of SSR to approximate the experimental signals, and on the other, that TOA represents an excellent index to estimate the surface area of the skin-core detachment.