New analytic model for torsion with shear influence of thin-walled composite beams with symmetrical open sections

New improved analytic model for torsion with shear influence of thin-walled composite beams with symmetrical open cross-sections is developed. It is assumed that the beams are assembled of balanced, symmetric laminates with constant elastic properties over the cross-section area. Solutions for the stresses, as well as for the displacements, with the shear deformation in mid-surface taken into consideration, are presented in closed analytic form. The influence of shear effect on normal stress distributions and angular displacements is investigated with respect to fiber orientations in laminate plies. Beams with different boundary conditions, loaded with couples in cross-section planes, are assumed. The results obtained for the beams with low aspect ratios are validated by comparison with the finite element results. Shell elements were used in the modeling process. The obtained results are in excellent agreement.