Thermal Effect On Scale Effect Of Laminated Composite Plate

With the material size scaling down to the order of micro-scale, the conventional continuum theory is not capable of predicting such size effect. However, theories for microstructures have been proposed are only adaptable to isotropic material. In this paper, a new modified couple stress for anisotropic material is proposed. In this theory, employing the material length scale parameter of fiber and matrix is to build constitutive relationship for anisotropic elasticity, in which the curvature tensor is asymmetric, but couple tress tensor is symmetric. For isotropic material, it can be identical to modified couple stress theory.Based on the new modified couple stress theory and the Reddy displacement theory, a Reddy-type modified couple stress theory is developed to analyze the size effect of composite laminated beam/plate under thermal load. In this model, considering thermal strain, the Reddy displacement field which satisfied free surface conditions is used. According to the virtual work principle, the equilibrium equations have been obtained. The analytical solution of the thermal size-dependent of laminated composite beam/plate has been gained. Numerical results show that the size effect of material has to been considered for the thermal load of laminated composite micro-beam/plate.