Role of Laminate Thickness on Sequential Dynamic Delamination of Curved [90/0] CFRP Composite Laminates

Abstract

In aerospace industry, high demand for the lightweight structures are fostering the use of carbon fiber reinforced polymer composites in a wide variety of shapes, as primary load carrying elements. However, once a composite laminate takes a highly curved shape, such as an L-shape, interlaminar stresses augmented in the curved region cause highly dynamic delamination nucleation and propagation. This paper provides experimental observations of dynamic delamination failure in cross-plied L-shaped composite laminates under quasi-static shear loading for varying laminate thickness. In the experiments, load-displacement curves are recorded and dynamic delamination events areas captured using a million fps high speed camera. In our previous work, two distinct types of failure modes have been identified depending on the laminate layup: (i) formation of multiple delaminations leading two single load drop in its load-displacement curve during the failure of unidirectional laminates, [0]17, and (ii) formation of sequential delaminations associated with each discrete load drop in its load-displacement curve were during the failure of cross-ply laminates, [90/0]17. Accordingly this current study shows that formation of sequential delaminations is independent from the laminate thickness.