An analytical model for composite tubes with bend-twist coupling

A simple analytical model is derived for composite tubes subjected to bending and torsion. The model is applied to a novel design of composite tube that exhibits bend-twist coupling such that the shear center of the cross section is away from the tube axis. Analytical expressions are derived for the shear center distance - distance of the shear center from the tube axis. Finite element analysis of the tubes is performed using shell elements. The agreement between analytical and numerical results is excellent. It is found that the shear center distance is independent of the radius of the tube but proportional to the length of the tube and it is also a function of coefficient of mutual influence of the composite material.