Virtual Frequency Data Fusion for Localization of Multiple Damages from Broadband Lamb Wave Velocity Field

Abstract

In this article, a new damage indicator called reciprocal root mean square (rRMS) index is proposed for the localization of multiple damages in plate-like structures from the velocity field of guided wave propagation measured using Scanning Laser Doppler Vibrometer (SLDV). The Lamb waves are induced by applying voltage excitation to piezoelectric patch transducers pasted on the top of the plate. It is found that the velocity field measurement from one narrowband pulse excitation of a given central frequency may not be adequate in identifying the locations of all damages. To overcome this difficulty, a new methodology is proposed for a combined damage index that fuses measurement data of different excitation frequencies. However, obtaining the velocity field data at multiple narrowband frequencies from SLDV required for frequency fusion can be tedious, time consuming and expensive. To address this issue, velocity fields at various narrowband frequencies are virtually derived by utilizing the one-time physical velocity field measurement from a broadband excitation. The efficacy of the proposed method for damage localization using frequency fusion is experimentally tested. It is found that the proposed technique using rRMS index and frequency fusion is able to localize multiple damages of different types with high sensitivity.