Guided wave tomography of CFRP plates using the probabilistic algorithm

The rapidly increasing usage of carbon-fiber reinforced plastics (CFRP) calls for novel and more cost and time effective NDT inspection methods. As a response to this call, among other options, the Reconstruction Algorithm for Probabilistic Inspection of Damage (RAPID) has been previously introduced. This method originally utilizes the difference between ultrasonic signals acquired on a sample in an intact and in a damaged state in order to identify and furthermore localize damage sites in plate-like structures. This study demonstrates the applicability of the RAPID methodology to structures with more complex geometry and material properties such as aircraft wing parts made of CFRP. It will be shown that RAPID is able to detect and localize defects created by low-velocity impacts, as well as delaminations of different sizes. In the second part of the study, we propose an enhancement of the basic RAPID method by converting the method from a baseline-dependent approach to a baseline-independent one. In order to make this transition, we utilize excitation and signal processing techniques, such as pulse-inversion and scaling subtraction, which exploit the nonlinear behavior of defects in the structure. The feasibility of the combined RAPID and nonlinear methodology will be shown by simulations as well as by preliminary experimental results.status: accepte