Quasi-static Component Generation of Guided Waves and Its Applications on Damage Detection

Abstract

Quasi-static component (QSC) generation is a typical nonlinear effect of ultrasonic wave propagation, which can be used for materials characterization with the features of high sensitivity and low attenuative effect (generated QSC pulse's carrier wave frequency is zero). This study presents a novel method for early-stage microdamage detection and localization using QSC generation of ultrasonic guide wave L(0,1) mode propagation in pipes under group velocity mismatching condition. Finite element (FE) model was developed to provide insights on the generation and propagation characteristics of the QSC induced by both the global weak material nonlinearity and local microdamage in metallic pipes. FE analysis verified the L(0,1) mode of the QSC. The cumulation feature of QSC pulse was obtained in terms of the temporal pulse width and the pulse amplitude. A microdamage localization method was pro-posed based on the L(0,1)-QSC mode pair. Experiments were conducted in corrosion-induced aluminum pipes to investigate the QSC pulse signals. The QSCrelated nonlinear pulse signals caused by the material nonlinearity and micro-damage were detected and identified. The mode of QSC and feasibility of the proposed microdamage localization technique were verified. The FE and experimental results demonstrated the basic properties of QSC generation in isotropic metallic pipes and validated potential applications.