The aim of this paper is developing a new composite laminated size-dependent beam model based on a re-modified couple stress theory. Refined Zigzag Theory (RZT) is adopted for the kinematic assumptions of the displacement. The zigzag theory is a typical layer-independent theory, where a piecewise linear function of in-plane displacement along the thickness is postulated to satisfy the continuity conditions. The modified couple-stress theory has been used for considering the scale effect on the behavior of the micro beams. The re-modified couple stress theory contains only one material length-scale parameter in each ply of the composite laminated beam. The equations of motions are obtained using Hamilton’s principle and are solved by Galerkin method. The example of a cross-ply simply supported beam subjected to transverse load is presented. Numerical results show that the proposed beam model can capture the scale effect of the microstructure. The results of the presented formulation are compared with First order Shear Deformation Theory.
