LOCATING DAMAGES IN THIN ALUMINIUM PLATES USING LAMB WAVES AND AGENETIC OPTIMIZATION APPROACH

Abstract

A new damage localization method based on Lamb waves is presented here for thin aluminium (Al) plate specimens using a Genetic optimization (GO) approach. Two different types of damages are considered to demonstrate the effectiveness of the proposed method and its practical applicability. The lamb wave signals for interrogating the plate structure are obtained using experiments and a sparse array of four piezoelectric wafer (PW) transducers. The PW transducers are mounted onto the specimen in the form of vertices of a square roughly in the centre portion of the specimen to record the responses for pristine and damaged states of the specimen. The time of arrival (TOA) of defect waves to the sensor are extracted using the continuous wavelet transform (CWT) applied on all the residual signals and are subsequently used in the astroid algorithm to locate the damage as an enclosed area. The damage locations are further optimized within the enclosed area using the GO algorithm. The optimized results of damage well correspond with the actual ones and thus manifest the ability of the proposed approach for locating different types of defects in an Al specimen using a sparse array of permanently installed PW transducers.