A Comparison of Laser Shearography and C-Scan for assessing a Glass-Epoxy Laminate Impact Damage

Impact damage is a serious damage mechanism in composite materials, limiting their performance and reliability. Impact damage can occur during in-service applications or as a result of handling during manufacturing. Methods used currently for damage detection are based on different principles and for that reason, they give a range of results no matter what the real damage is. Therefore, a comparison of the internal real damage with the flaw indications of a glass fibre–reinforced polymer (GFRP) laminate made with two non-destructive technique (NDT) have been compared to evaluate their ability to detect real inner impact damage in glass fibre–reinforced laminates.

A metallographic evaluation was performed to determine the real state of the material. Moreover, the residual impression after impact was measured. Laser Shearography detects the surface residual indentation and reacts to surrounding damage. Even small damage from a 5 J impact that causes 0.1 mm deep dents with negligible delamination can be detected by Laser Shearography. This surface deformation can lead to a decrease in the toughness of construction, which may result in a reduced bearing capacity.