An improved model for naturally curved and twisted composite beams with closed thin-walled sections

This paper presents an improved model for naturally curved and twisted anisotropic beams with closed thin-walled cross-sections. By introducing eigenwarping functions and expanding axial displacements in series of eigenwarpings, the differential equation involving the generalized warping coordinate and the expression for eigenvalues can be derived using the principle of minimum potential energy. In the model the effects of some factors such as the initial curvature, torsion of the beams as well as torsion-related warping, transverse shear deformations and elastic coupling are incorporated. As an application, the present model is adopted to do an analysis for closed thin-walled composite box beams. Comparison with the existing experimental observation and numerical results shows that the proposed model is valid for analyzing such naturally curved and twisted beams.