Full-scale FEA of Lamb Wave with Piezoelectric Transducers for Damage Detection in Aluminium Plate

Structural health monitoring (SHM) is an emerging research area with multiple applications. There is a large number of non-destructive evaluation (NDE), non-destructive testing (NDT), and non-destructive inspection (NDI) techniques for identifying local damage and detect incipient failure in critical structures. Lamb waves, or plate waves, are ultrasonic elastic waves that travel inside and along thin plates and is frequently used as diagnostic tools to detect damage in plate-like structures. In this paper, finite element simulation of Lamb wave with piezoelectric transducers for plasticity-driven damage detection in an aluminum plate is carried out. The aluminum plate shaped at 681mmx720mmx1.6mm and nine rectangular piezoelectric disks are surface bonded. The embedded two-dimensional piezoelectric wafer active sensors were used to generate and receive guided Lamb waves propagating in the plate structure. The plasticity damage zone is 18mmx24nun and produced by reducing the thickness of the plate. The material of this zone takes into plasticity when the plate is tensioned, but other area is in elastic. A full-scale FEM model for the aluminum plate was created using shell elements and piezoelectric active sensors were created using coupled field elements on the commercial finite element code ANSYS 9.0 platform. The FEM mesh was particularly densified in the plate, where more than 6 FEM nodes per Lamb wavelength were guaranteed to exist, and ensuring simulation precision. A virtual beam steering method with time delay was implemented as a signal post-processing procedure to locate the damage. The results of the numerical simulation demonstrate that the approach can detect the structural plasticity-driven damage.