Shear Coefficient in Orthotropic Thin-Walled Composite Beams

Abstract

The shear coefficient in Timoshenko beam theory is derived for thin-walled beams constructed of orthotropic laminated composite panels and new formulas for the common forms of thin-walled section are presented. The results are identical to Cowper's for the case of isotropic beams. Comparison is also made with the shear coefficient presented by Bank (1987). A parametric study is conducted to evaluate the effect of cross section dimensions and the mechanical properties of the laminated panels on the shear coefficient. The transverse shear deformation and its relative importance compared to bending deformation is investigated for this class of composite beams. For thin-walled sections constructed from laminated panels made of a combination of 0° unidirectional and angle-ply laminae, the optimal ply angle for different percentages of angle-ply laminae, is found to minimize the total static deflection of the beam. This lay-up configuration is the most practical and effective distribution of plies in laminated composite thin-walled beams to meet the design serviceability requirements (i.e., deflection and vibration).