Refined Beam Theory for Geometrically Nonlinear Pre-Twisted Structures

This paper proposes a novel fully nonlinear refined beam element for pre-twisted structures undergoing large deformation and finite untwisting. The present model is constructed in the twisted basis to account effects of geometrical nonlinearity initial twist. Cross-sectional allowed by introducing Lagrange polynomials framework Carrera unified formulation. principle virtual work applied obtain Green–Lagrange strain tensor second Piola–Kirchhoff stress tensor. In governing formulation, expressions are given secant tangent matrices with linear, nonlinear, geometrically stiffening contributions. developed could detect coupled axial, torsional, flexure deformations, as well local deformations around point application force. maximum difference between results those shell/solid simulations 6%. Compared traditional theories models, proposed method significantly reduces computational complexity cost implementing constant elements basis.