Rotational invariants in finite element formulation of three-dimensional beam theories

This paper introduces a new finite element formulation of the ‘geometrically exact finite-strain beam theory’. The formulation employs the generalized virtual work principle. In the resulting governing equations of the beam, the strain vectors are the only unknown functions. The consistency condition that the equilibrium and the constitutive internal force and moment vectors are equal, is enforced to be satisfied at chosen points. The accuracy and the efficiency of the derived numerical algorithm are demonstrated by several examples.