Imaging of Lamination Defect in Metallic Plate Based on Local Wavenumber Domain Analysis

Abstract

In metallic plate structures, a lamination defect is a type of internal defect that is commonly generated in the manufacturing process, which is mostly parallel to the surface of the plate. This study presents a technique of imaging a lamination defect in a metallic plate by using Lamb waves based on the local wavenumber domain analysis method. Owing to the processing technique, an aluminum beam structure is utilized to represent the metallic plate for the detection of the lamination defect. A three-dimensional finite-element model of an aluminum beam with a rectangular lamination defect is constructed with MatLab and ABAQUS commercial software. The propagation characteristics of Lamb waves are discussed by analyzing the simulated wavefield. A complicated wave-propagation phenomenon of multiple reflection and transmission is observed between the interaction of Lamb waves and the lamination. By performing local wavenumber domain analysis on the wavefield, the wavenumber distribution is obtained, from which the location and profile of the lamination defect are identified. An experimental study is carried out to verify the numerical result. A fully non-contact detection system consisting of an electromagnetic acoustic transducer and laser ultrasonic inspection system is established to inspect the artificial machined beam structure. The experimental result is in good agreement with the numerical result.