Numerical Study of the Propagating Properties of a Laser-Generated Surface Acoustic Wave Interacting with a Bracket Structure

Abstract

Shield tunneling machines are widely used around the world for construction in tunnels, railways, and subways. The bracket of a shield tunneling machine, which is welded to the cutterhead, is prone to suffer maximum stress due to its bad operating environment. This paper introduces a laser-generated surface acoustic wave for non-destructive detection. A numerical model is constructed to analyze the interaction between a laser-generated surface acoustic wave and a bracket structure. The results show that the laser-generated acoustic wave with a longitudinal wave, a shear wave, and a Rayleigh wave can propagate along the surface of the bracket structure. When the wave encounters the junction of the welding and the horizontal surface, it generates a reflected wave, a transmitted wave, and a mode converted wave. This propagating phenomenon can be used for the defect detection of a bracket in the future.