Quantitative tomographic visualization for irregular shape defects by guided wave long range inspection

Abstract

Ultrasonic guided waves have been proven as a promising tool for structure health monitoring due to their capability of interrogating a large structure from a single transducer position. This study presents the guided wave tomographic imaging in structural health monitoring for detecting cracks and visualization by reconstruction algorithm for the probabilistic inspection of damage. The variable shape factor is suggested for quantitative defect shape and sizing by reconstruction image. The defect of irregular boundary imaging with variable shape factor is precisely reconstructed by advanced RAPID algorithm with limited number of transducers. The particular application of interest is defect imaging of symmetric wave modes with irregular shape defect in plate-like structures. A preliminary study of tomographic imaging by guided waves in a plate-like structure provides guidelines for the quantitative defect imaging.

An Investigation on a Quantitative Tomographic SHM Technique for a Containment Liner Plate in a Nuclear Power Plant with Guided Wave Mode Selection

“…In addition, from the practical viewpoint, the variable shape parameter β in the RAPID algorithm is not applied to the results, which is estimated to affect the shape of the reconstructed images. Data obtained in previous studies using the variable shape parameter are used to obtain exquisite and enhanced reconstruction images [21,23].…”

“…Finally, the significant result from GW based SHM is that the tomographic image reconstruction, based on the RAPID algorithm, is successfully illustrated using the symmetric 3.0 MHz·mm Lamb wave mode. In future work, the RAPID tomographic algorithm involving the variable shape parameter technique [21,23] should be used to improve visualization of the shape of defects for the CLP facility. In addition, with the application of omnidirectional transducer, an annular type of transmitter–receiver [28,30], this evaluation technique is expected to reinforce the reliability and feasibility to monitor CLP.…”

“…Earlier research showed that qualitative defect imaging with ghost imaging was able to describe the accurate size of the failure. Guided wave tomographic visualization shows great potential in identifying the defect’s location and quantitative sizing [21,22,23,24].…”

“…Defects having simple shapes, such as a circle, are quantitatively illustrated using a variable shape factor [22]. For defects having irregular shapes or in the case of multiple defects, clarifying reconstruction image techniques are studied based on the RAPID algorithm using variable shape factor approach [23]. For the development of highly accurate defects, especially wall-thinning depth, the full wave inversion (FWI) algorithm is significantly studied for corrosion damages and wall-thinning defects [25].…”

Defect Imaging Enhancement through Optimized Shape Factors of the RAPID Algorithm Based on Guided Wave Beam Pattern Analysis

“…Many researchers have tried to focus on establishing an SHM system and providing a solution for inaccessible defects in structures. For applications of the RAPID algorithm, the variable shape factor was investigated by considering the location and shape of the defects (circular and quadrilateral shapes) [12]. The variable shape factor approach shows a remarkable enhancement of reconstruction of defect images.…”