Damage localization in cross-ply laminated composite plates under varying temperature conditions using Lamb waves

Lamb wave-methods are reported to be very effective in detecting and localizing defects in thin plate structures. However, the accuracy of damage detection using Lamb waves is affected significantly by variations of environmental and operating conditions. In the present study, an improved methodology is presented to calculate the damage residue measure from current state responses that compensates the effect of operational and environmental changes. The proposed damage residue is obtained by comparing the current state responses of identical paths with the same propagation distance and direction. For damage localization in the structure, a modified delay-sum damage localization algorithm is introduced. The proposed damage residue measure is used along with the modified delay-sum algorithm to locate damage in a composite plate. The methodology is first presented through numerical simulations based on a finite element model and validated through experiments on a carbon fiber cross-ply configured composite plate. The insensitiveness of the proposed residue measure to temperature changes is demonstrated experimentally.