A geometrically exact nonlinear finite element for composite closed section thin-walled beams

A geometrically nonlinear beam finite element for composite closed section thin-walled beams considering arbitrary displacements and rotations is presented. The virtual work equations are written as a function of nine generalized strain components, which are parametrized in terms of the director field and its derivatives. The presented finite element is valid for both isotropic and anisotropic materials. The proposed approach could be attractive to be used in optimization problems of composite thin-walled beams with finite deformation such as helicopter rotor blades and wind turbine blades. It is shown that the proposed formulation has an excellent correlation against shell finite elements.