Higher-order shear deformation theory for thin-walled composite beams

A higher-order shear deformation theory for the static and dynamic analysis of thin-walled composite beams of arbitrary lay-ups and cross sections is presented. The method is applicable to beams of open as well as closed cross sections. The formulation includes Euler-Bernoulli and Timoshenko theories as subsets. The bendingand torsion-related warping functions are derived in closed form. The method is validated by comparison with experimental and analytical results for static deflections of composite beams with symmetric and antisymmetric lay-ups. Comparison with experimental results for the vibration of beams exhibiting bending torsion coupling shows that the present method gives better correlations. The significance of the higher-order theory is brought out by validating the results of the analyses against results from other theoretical methods. The results show the importance of the lay-up sequence on the shear lag in thin-walled composite beams.