Retrieving Variable Stiffness Laminates from Lamination Parameters Distribution

Abstract

Throughout literature variable sti!ness composite structures have been reported to perform significantly better than constant sti!ness baseline designs. In order to take full benefit of the advantages tailored composites o!er, several design and optimisation methods have been investigated. By using lamination parameters (LP) the number of design variables of such optimisation can be successfully reduced to a finite set of continuous, dimensionless variables. In order to construct a manufacturable laminate, the optimal LP distribution found for a structure must be converted into a stacking sequence distribution. Which requires a procedure that is able to retrieve a stacking sequence from a given set of LPs. This paper investigates stacking sequence retrieval from a given set of LPs, and the importance of the relation between in-plane and flexural LPs in this process. Based on this study a new analytical retrieval procedure is presented. The new procedure is compared to two existing procedures, and a method to incorporate manufacturing constraints using the new procedure is suggested. The ability of the proposed framework is demonstrated for a square plate, optimised for buckling performance using LPs. Not only is the new procedure found to perform better than existing methods, but it does appear possible to convert an LP distribution into a stacking sequence distribution satisfying production constraints with a negligible loss in performance.