Ultrasonic guided waves for nondestructive evaluation/structural health monitoring of trusses

Ultrasonic guided waves (UGWs) are particularly effective in those nondestructive evaluation and structural health monitoring applications that benefit from built-in transduction, moderately large inspection ranges and high sensitivity to small flaws. This paper describes a method to detect cracks in large trusses that combines the advantages of UGWs with the extraction of defect-sensitive features to perform a multivariate diagnosis of damage. The proposed algorithm was applied to the guided waves propagating along one of the main chords of a dismantled overhead sign support structure. The probing hardware consisted of a data acquisition system that controlled the generation and detection of ultrasonic signals by means of piezoelectric transducers made of lead zirconate titanate. The effectiveness of the proposed approach to diagnose the presence of an artificial defect around the welded joint between one main chord and a diagonal member of the truss structure is explained.