Evaluation of welding damage in welded tubular steel structures using guided waves and aprobability-based imaging approach

Abstract

Welded tubular steel structures (WTSSs) are widely used in various engineering sectors,serving as major frameworks for many mechanical systems. There has been increasingawareness of introducing effective damage identification and up-to-the-minute healthsurveillance to WTSSs, so as to enhance structural reliability and integrity. In this study,propagation of guided waves (GWs) in a WTSS of rectangular cross-section, a true-scalemodel of a train bogie frame segment, was investigated using the finite element method(FEM) and experimental analysis with the purpose of evaluating welding damage in theWTSS. An active piezoelectric sensor network was designed and surface-bonded on theWTSS, to activate and collect GWs. Characteristics of GWs at different excitationfrequencies were explored. A signal feature, termed ‘time of maximal difference’ (ToMD) inthis study, was extracted from captured GW signals, based on which a concept, damagepresence probability (DPP), was established. With ToMD and DPP, a probability-baseddamage imaging approach was developed. To enhance robustness of the approach tomeasurement noise and uncertainties, a two-level image fusion scheme was furtherproposed. As validation, the approach was employed to predict presence andlocation of slot-like damage in the welding zone of a WTSS. Identification resultshave demonstrated the effectiveness of the developed approach for identifyingdamage in WTSSs and its large potential for real-time health monitoring of WTSSs.