Nondestructive evaluation of low-velocity impact-induced damage in basalt-carbon hybrid composite laminates using eddy current-pulsed thermography

Recently, basalt-carbon hybrid composite structures have attracted increasing attention due to their comprehensive mechanical performance, if compared to carbon fiber reinforced polymer composites (CFRP). Low-velocity is considered as one of the most severe threats to composite products, since it is usually invisible and it occurs frequently in service. In this regard, non-destructive testing (NDT) techniques, especially emerging modalities, are expected to be an effective damage detection method. In this paper, eddy current pulsed thermography (ECPT), as an emerging NDT technique, was used to evaluate the damage induced by low-velocity impact loading in a CFRP laminate, as well as in two different-structured basalt-carbon hybrid composite laminates. In addition, ultrasonic C-scan and X-ray computed tomography were performed to validate the thermographic results. Pulsed phase thermography, principal component thermography and partial least squares thermography were used to process the thermal data and to retrieve the damage imagery. Then, a further analysis was performed on the imagery and temperature profile. As a result, it is concluded that ECPT is an effective technique for hybrid composite evaluation. The impact energy tends to create an interlaminar damage in a sandwich-like structure, while it tends to create an intralaminar damage in an intercalated stacking structure.