Numerical modeling of guided-wave acoustic emission from weld cracking: butt welds, T-joints, and precracks

Abstract

his paper presents results from an investigation of localized geometrical effects on crack-induced acoustic emission in welded plate-like structural components. The aim is to better understand the influence of weld geometry and precracking on the radiation patterns of guided waves. Attention is confined to the fundamental symmetric (S₀), antisymmetric (A₀), and shear-horizontal (SH0) guided modes. Numerical modeling is used to study cases of butt welds, T-joint welds, and finite-length full-penetration precracks. The numerical model is referenced against an analytical model which neglects these geometrical effects. Butt welds are shown to have a relatively small, and perhaps negligible, influence on radiation. T-joint welds exert a much stronger influence, especially behind the joint. Ahead of the joint, the S0 and SH0 modes are less affected. In the precrack case, mode conversion from a Rayleigh mode into the SH0 mode is shown to enhance primary radiation behind the precrack. An SH0 metric is therefore introduced, which shows crack-sizing potential up to about five plate-thicknesses.