Design of anisotropic composite shells using an isogeometric approach

Thin-walled composite structures, typically modeled as Cosserat continua during the design phase, are of particular importance in aerospace and automotive applications. At the dawn of industrial scale adoption of advanced fibre placement technology, it became viable to better exploit the directional properties of composite materials. In the recent past, numerous researches were devoted to the design of shells with optimal anisotropy. In the present work, combined stiffness tailoring and shape optimal design is proposed that is naturally facilitated in a non-uniform rational B-spline based isogeometric approach. Spatial variation of stiffness properties is parameterised by means of lamination parameters and the thickness of the shell. Shape changes are easily achieved by modifying selected control point co-ordinates and weights. The method of successive approximations has been employed to solve the optimisation problem. The formulation is separable in terms of sizing variables, however, separability of the shape design problem is not enforced. The design framework is verified through selected compliance minimisation problems