Double–Double laminates for aerospace applications — Finding best laminates for given load sets

The Double–Double (DD) family of laminates is characterized by the parametric laminate description ±φ,±ψrT. DD promises considerable advantages for aerospace laminates, as the unique combination of the laminates’ building-block architecture simplifies manufacturing and in particular laminate optimization. DD eliminates complicated permutation issues know from conventional laminates and allows for easy stiffness tailoring, by locally varying repeats r. The present paper proposes a DD-laminate optimization scheme for laminate-strength, which focusses on robustness in the identification of safe laminates. The scheme is presented for a multi-load scenario, each consisting of five individual loads. The combination of the Nettles circle failure enveloped in principle strain with the DD features lead to a rather simple optimization scheme, accompanied by meaningful illustrations, which are presented in the present paper.