Structure mechanical modeling of thin-walled closed-section composite beams, Part 1: Single-cell cross section

An improved structure mechanical modeling with excellent accuracy is developed for single-cell thin-walled closed-section composite beams based on previous work. Both axial warping effect and the effect of material anisotropies on the shell wall mid-surface shear strain are considered. The shear strain is calculated directly from the general constitutive law of the shell wall. Closed form expressions are obtained of one-dimensional global beam stiffness matrix. Numerical comparisons with ABAQUS simulations are performed for box and cylindrical beams with a variety of lamina layups under various loading conditions and excellent agreements are observed. The effect of material anisotropies on the shell wall mid-surface shear strain has significant influence on the accuracy of modeling. In contrast, the axial warping effect has a negligible influence in cases considered. Significant deficiency of some existing models is revealed.