Three-dimensional stress analysis in torsion of laminated composite bar with general layer stacking

A general laminated composite bar with rectangular cross-section which is subjected to torsional torque is studied and the three dimensional stress state, specially the out of plane stresses is investigated. A reduced displacement field is obtained for the long laminated bar in which the global and local deformation response of the laminate are separated. This reduced displacement field is obtained from integration of the strain components. In order to obtain the three dimensional stress state and free edge effect, the displacement based layer-wise method is employed for formulation of the problem and the governing equations are solved analytically. The numerical results are compared with the predictions of multi-term extended Kantorovich method and mixed-field multi-term extended Kantorovich method which is available in the open literature and with an analytical series solution, and very good agreements are achieved. The twisting, extension, and bending of laminate due to torsion torque, and the out of plane and in-plane stresses are studied for various layers stacking. In order to increase the accuracy, the out of plane stresses are obtained by integrating the equilibrium equations.