Analysis of shear lag and shear deformation effects in laminated composite box beams under bending loads

A method for analyzing the shear lag and shear deformation effects on symmetrically laminated thin-walled composite box beams under bending load is presented. The method is based on the theory of composite laminated plates and is deduced by means of the principle of minimum potential energy, which makes the procedure simple and practical. The formulas given by this method not only satisfy the equilibrium conditions on the cross-section of the thin-walled composite box beams but can be simplified to the known formulas of thin-walled box beams with isotropic materials as well. Finally, an example is given and its numerical results are analyzed and discussed. The values of vertical displacements and ply normal stresses obtained by this paper are compared with those obtained by the finite element method (FEM) or previously published experimental and numerical results, respectively. A comprehensive analysis on the effects of shear lag and shear deformation is given for a simply supported thin-walled composite box beam subjected to a centralized load at mid-span.