Lamb Wave‐BasedSHMfor Laminated Composite Structures

Abstract

This article examines the application of low‐frequency Lamb waves for the detection of delaminations (interlaminar cracking) in thick composite laminates. Surface‐mounted piezoelectric devices are excited with a tone burst of a few cycles generating a stress wave that propagates along the structure. Experiments carried out on composite beam specimens are discussed where wave propagation distances over 2 m are achieved and delaminations as small as 1 cm 2 are successfully identified. The resonance spectrum method, which is based on the study of spectra obtained by forced mechanical resonance of samples using sine‐sweep excitation, is used for measuring the A o Lamb‐mode phase velocity. Finite element (FE) analyses of wave generation and propagation in wide laminated plates are also presented. The feasibility of employing piezoelectric devices for the development of smart structures, where a small and lightweight transducer system design is required, is also demonstrated.

Prediction and Measurement of Lamb Wave from Debondings at Structural Features in Composite Laminates

“…2D FE simulations and experimental studies showed that the power transmission of Lamb waves can be used to evaluate the integrity of the repair patches. Soutis and Diamanti [21] demonstrated the use of Lamb waves to inspect adhesively bonded patch repaired composite laminates. The study specifically focused on the low frequency fundamental anti-symmetric (A 0 ) Lamb wave.…”

Scattering characteristics of Lamb waves from debondings at structural features in composite laminates

“…As discussed in Sec. I.B, a number of studies have modelled these joints and repaired composite laminates using similar approaches [33][34][35][36] . As shown in Fig 1, the centre of a 22 mm wide structural feature was located at x  0 mm.…”