Defining the design space for double–double laminates by considering homogenization criterion

The double–double (DD) laminate families that contain two continuous angles, which were proposed by Tsai (“Double–Double: New Family of Composite Laminates,” AIAA Journal, Vol. 59, No. 11, 2021, pp. 4293–4305), opened up a whole new era for composite layups, which are easy to manufacture and design. In the present study, the design space referred to as feasible regions is derived explicitly based on novel formulations for the lamination parameters of DD laminates. This enables the boundaries of the design space to be obtained analytically, providing mathematical support for DD families. The obtained result shows that their design space is larger than that of conventional quadaxial laminates in terms of industrial practices. Ahomogenization criterion is implemented into the design space, based on which a tailored DD laminate is proposed, expanding design possibilities and enabling homogenization to be achieved using only 16 plies/4 repeats. The work proposed offers significant benefits through practical solutions to making design, manufacturing, and testing simpler and more competitive.