Simulation of Lamb Wave Propagation Using Excitation Potentials

Abstract

Acoustic emission (AE) can be used to measure energy associated with inelastic deformation such as slip, twinning, and microcracking, etc. in a structure. By obtaining AE information during a damage process, the failure indication can be detected. Therefore, better understanding of AE from a damage process is essential for proper damage detection. Elastic waves emission from a damage process due to energy release can be generalized by excitation potentials. There are two types of potentials exists in a plate for straight crested Lamb waves: pressure potential and shear potential. Theoretical formulation showed that due to excitation potentials the elastic waves in a plate followed the Raleigh-Lamb wave equation. The total energy released from damage can be decomposed as pressure potential and shear potential. Each potential has contribution to different wave modes. A numerical simulation was conducted to identify different wave modes due to excitation potentials. Out of plane displacement was calculated numerically on top of the plate at 500 mm distance from excitation point in each of 2mm, 6mm and 12 mm thick stainless steel plate. There were large losses in peak signal amplitude of anti-symmetric fundamental mode (A0) with increasing plate thickness from 2mm to 12 mm.