An innovative method for automatic determination of time of arrival for Lamb waves excited by impact events

Abstract

Lamb waves have great potential as a diagnostic tool in the application of structural health monitoring. Propagation properties of Lamb waves are affected by the state of the structure that the waves are traveling upon. Thus Lamb waves can carry information about the structure as they travel across a structure. However, the dispersive, multimodal and attenuation characteristics of Lamb waves make it difficult to determine the time of arrival of Lamb waves. To deal with these characteristics, an innovative method to automatically determine the time of arrival for impact-induced Lamb waves without human intervention is proposed in this paper. Lead zirconate titanate sensors mounted on the surface of an aluminum plate were used to measure the Lamb waves excited by an impact. The time of arrival was determined based on wavelet decomposition, Hilbert transform and statistics (Grubbs’ test and maximum likelihood estimation). Both of numerical analysis and physical measurements have verified the accuracy of this method for impacts on an aluminum plate.

Impact Localisation in Composite Plates of Different Stiffness Impactors under Simulated Environmental and Operational Conditions

“…Methods that are based on the physical behaviour of wave propagation in the observed structure may require complex modelling/solving [8,15,18] or may not be suited to complex structures (cut outs, etc.) where wave propagation is indirect [9,19,20]. Data driven methods are able to generate meta-models that directly map lamb wave features to a specific impact coordinate, thus bypassing the need for physical models and giving flexibility to accommodate complex structures [11,12,21,22].…”

Impact Localization in Composites Using Time Reversal, Embedded PZT Transducers, and Topological Algorithms

“…However, TOA-based techniques require a relatively large number of receiver transducers measuring the coherent part of the wave field (ballistic wave). Advanced signal processing methods such as peak detection (Castro et al, 2018;Das and Leung, 2018;Zhou et al, 2019), cross-correlation (Kim et al, 2015;Li et al, 2018), Hilbert (Chen et al, 2018;Kim and Yuan, 2018), and wavelet transformation (Bianchi et al, 2015;Zhu et al, 2017) have been employed to extract physical parameters from measured data in order detect AE waves. Nevertheless, the dispersive nature of guided waves, as well as boundary reflections and mode conversion in geometrically complex components can all alter the acquired signal resulting in incorrect TOA estimations (Ciampa and Meo, 2011).…”

Interfacial Debonding Detection for Rectangular CFST Using the MASW Method and Its Physical Mechanism Analysis at the Meso-Level

“…Hence, systematic investigation on the guided wave is a pre-requisite for choosing the appropriate excitation and mode type to improve the accuracy and efficiency of the NDT tests. The ultrasonic waves generated by the PZT patches, electro-acoustic transducer and lasers have been applied to the health monitoring of bond failure, the delamination in multi-layered plate-like composites, the debonding caused by corrosion of the steel bars and the defect in tubular waveguides [50,51,52,53,54,55,56,57,58]. The slender CFSTs specimens can be analyzed as rod-like waveguides since the diameter-height ratio is very small.…”