Nonlinear Guided Wave Mixing for Fatigue Damages Identification in Steel Pipe

Abstract

Nonlinear guided wave mixing techniques have been widely used for material degradation characterization in solids. In this study, a method using nonlinear guided wave mixing is proposed to identify fatigue damages, including both material degradation and subsequent fatigue crack propagation, in steel pipes. By means of theoretical analysis, two incident waves are selected to generate combined harmonics in the damaged pipes. Based on finite element (FE) simulations, the combined harmonic at difference frequency is successfully observed, and the nonlinear index, β, based on the combined harmonic at difference frequency is found to be capable of identifying both material degradation and the subsequent fatigue crack. This study provides a promising method for fatigue damages identification in the early stage using nonlinear guided wave mixing approach.