On the generation of quasi-orthotropic laminates with a building block incorporating an ISO60-base

The concept of quasi-orthotropic laminates has recently developed thanks to the introduction of so-called Double-Double (DD) laminates by Prof. S. TSAI and his team. We propose here to generate a class of quasi-orthotropic (QO) laminates from a “meta-set” consisting of two well-identified sub-sequences. One of which, isotropic in stiffness in its plane with a ply number equal to 3, can be obtained on a Pre-Plied Tape without crimping, so called NCF (Non-Crimp Fabric) tape. Given the low relative thickness required for each sequence, the following study focuses primarily on high-performance laminates—such as CFRPs—for which the aim is the mass optimization. To do this, we will rely on an underutilized property: « All plane laminates made up of orthotropic (e.g., unidirectional) plies derived from one another by rotation in the plane of π n ( n > 2 ) with identical proportions according to each orientation, are isotropic in stiffness in this plane. They have the same modulus of elasticity and the same Poisson’s coefficient ∀ n > 2 ». The following shows that it is possible to generate quasi-orthotropic laminates that are very easy to design and dimension to meet specific requirements. In terms of strength, they also benefit from concepts developed for quasi-orthotropic DD laminates (Omni Strain Failure Envelopes for Laminates).