Interlaminar fracture testing of multidirectional laminates: on finitewidth effect and residual stresses

Abstract

Fibre reinforced polymers, and in particular laminated plates, are widely used in structural applications. Interlaminar fracture (delamination) is a critical damage mechanism for these materials. Interlaminar fracture toughness is characterised using unidirectional specimens. While the toughness at interfaces in multidirectional laminates may be different, there is no consensus on how to effectively characterise it, due to a number of challenges associated with the use of multidirectional specimens. In this work, we review in detail some of these problems, namely, 3-dimensional effects and residual thermal stresses. We then present a strategy to design a set of Fully-Uncoupled Multidirectional specimens enabling a further understanding of these problems