Thin-ply polymer composite materials: a review

The introduction of the spread-tow thin-ply technology enabled the development of composite plies as thin as 0.020 mm. The availability of composite plies with a broader thickness range makes the understanding of the effects of ply thickness more pertinent than ever, therefore, a comprehensive literature review is presented in this paper. The micro-structural effects of ply thickness and ply uniformity on the mechanical response of unidirectional laminae is described. Then, the effect of ply thickness scaling on several aspects of the mechanical response of composite laminates is reviewed. Finally, the current state-of-art and recent developments in manufacturing, design and application of thin plies on novel engineered composite laminates are presented. This review demonstrates that thin plies not only bring improvements to the plain strengths and design flexibility of composite laminates, but can also enhance the performance of primary structural applications, namely those driven by residual strength and damage tolerance requirements. This can be achieved by either combining thin plies with existing material technologies, or through novel design principles. Moreover, it is shown that thin plies provide increased flexibility for multifunctional optimisation and for adoption of more efficient manufacturing technologies, with great potential gains in terms of weight savings and cost reduction during conceptual and detailed design and operation.