On the correlation between stiffness and strength properties of anisotropic laminates

Abstract

This paper focuses on the analytical formulation of a tensorial laminate-level failure criterion. The criterion is formulated and expressed in the framework of the first-order shear deformation theory (FSDT) in order to take into account the influence of the transverse shear stresses on the failure mechanisms. More precisely the most common polynomial ply-level failure criteria (expressed under a unified matrix formulation) are considered and reformulated at the laminate level. The proposed unified formulation relies on the utilisation of the polar formalism gener- alised to the FSDT framework. Through this approach all the considered criteria can be formulated in terms of tensor invariants. Furthermore, thanks to the polar representation, an important theoretical result is proven: the existence of a set of analytical relationships between the laminate strength and stiffness invariants.