Torsion of thin-walled composite beams with midplane symmetry

The optimization of thin-walled beams can lead to the design of structures whose walls have significant differences in stiffness. The stress field resulting from a twisting moment is not correctly modeled by classical analytical theories, so numerical modeling is therefore essential. The analytical theory presented in this study provides us with a simple way of determining stress and stiffness in this type of structure, without having to resort to complex methods of calculation. The walls are made of isotropic or composite materials with midplane symmetry and one orthotropic axis is the longitudinal axis. The section may be open or closed and the constrained warping effect can be taken into account. The results obtained correlate accurately with those obtained from 3D FE modeling