M. J. khoshgoftar - Department of Mechanical Engineering, Faculty of Engineering, Arak University, Iran
M Ghasemi - MSC Student, Department of Mechanical Engineering, Faculty of Engineering, Arak University, Iran

The aim of this paper is developing a new composite laminated size-dependent beam model based on a remodified couple stress theory. Refined Zigzag Theory (RZT) is adopted for the kinematic assumptions of the displacement. The zigzag theory is a typical layerindependenttheory, 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 remodifiedcouple 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 supportedbeam 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

modified couple stress theory, scale effect, composite laminated beam, zigzag theory