A proof of the convexity of a set of lamination parameters

Abstract

In this paper we show that the proof of the convexity of the set of lamination parameters given by J.L. Grenestedt and P. Gudmundson, which is extensively cited in the literature, is not correct. We give a proof of the convexity of this set when the class of layup functions is the set of step functions. Moreover we give a proof of the non‐convexity of this set when the class of layup functions is the set of step functions where the layers have the same thickness and the number of layers is not fixed.