A study on guided wave tomographic imaging for defects on a curved structure

Guided wave tomography is a very attractive technique for online nondestructive evaluation and structural health monitoring. The reconstruction algorithm for probabilistic inspection of damage (RAPID) is an effective tomography algorithm for detecting, locating, and imaging defects. Conventional tomography imaging techniques are difficult to quantify defects in structures with curved surfaces like aircraft. It is not a complete tool for evaluation of a damaged area on a curved surface, because of insufficient guidelines for shape factor (Bata) and curvature. Probabilistic inspection of damage is used to construct tomographic images of hole defects in a 30 mm diameter and thickness 5 mm carbon steel plate and curved surface specimen. Imaging is completed using an array of 16 transducers. It is shown that defect location can be accurately determined on plate and curved surfaces. The work presented here introduces a calculation for the shape factor for evaluation of the damaged area, as well as a variable beta parameter technique to correct a damaged shape. An experiment is performed using the guided wave pitch-catch method to find the length of the damage on a ray path. Also, we perform research in modeling simulation and an experiment for comparison with a suggested inspection method and verify its validity. In the plate and curved surface images resulting from the advanced RAPID algorithm, the defect area and shape showed good agreement. Quantitative imaging techniques on the surface can be applied to real-time defects imaging of aircraft component monitoring.