Some exact solutions for fully orthotropic laminates

This paper presents a study about in- and out-of-plane orthotropy in the same axes for bending-extension uncoupled laminates composed of orthotropic layers. Usually, uncoupling is obtained using symmetric stacking sequences, but in this case bending orthotropy is very difficult to be obtained. We propose in this paper an approach based upon the use of antisymmetric laminates, that are automatically in- and out-of-plane orthotropic in the same axes, but usually coupled: the goal is then to find the condition to satisfy in order to obtain uncoupling. The methodology proposed in the paper obtains solutions for laminates with a minimum of 6 layers. In the paper, the complete set of solutions is provided for 6- and 7-ply laminates, and the methodology to find solutions for a higher number of layers is presented.