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Category: Project

Description: Thin ply materials represent today one of the most promising composite material for advanced applications in the aerospace industry, thanks to the developments in the so-called spread tow technology. Due to its capacity of avoiding fibers' breakage and surface property loss, this technology has been applied on an industrial scale to produce extremely thin fiber-reinforced prepreg plies. Initially devoted to sports equipment, thin-ply laminates are recently attracting the interest of aerospace structural designers for use in mission-critical applications such as cryogenic tanks and reusable space launchers' frames. Experimental evidence collected on thin-ply laminates suggest that these composites are capable of delaying and even suppressing the propagation of transverse cracks and the onset of delamination. It thus seems to confirm a much earlier result on the influence of thickness and lay-up sequence on the strength and crack suppression behavior of FRP laminates, namely the existence of the so-called thin-ply effect and in-situ strength. In-situ observations point to debonding at the fiber/matrix interface as the primary mechanism to investigate in order to achieve a better understanding of the initiation of transverse cracking and its suppression through an improved laminate design. It is paramount to this end to understand the process of fiber/matrix debonding, kinking and coalescence, as well as the effect of ply thickness, fiber cluster size, material properties’ mismatch and thermal strains.