A Laminated Beam Model for the Effective Tensile and Bending Elastic Moduli of Nanowires

Surface elasticity has a strong influence on the size-dependent mechanical properties of nanowires (NWs). In this work, a laminated beam model is used to predict the effective tensile and bending moduli of a NW. The surface layer is assumed to have a definite thickness and different elastic moduli from the bulk layer. The effective moduli of the NW are expressed as a function of surface thickness and surface constant. The theoretical predictions for stiffening and softening effects are in good agreement with experimental results. High surface elasticity increases the bending modulus more than the tensile modulus. Low surface elasticity decreases the bending modulus more than the tensile modulus. Surface thickness has a considerable influence on the effective modulus of NW and amplifies stiffening and softening effects. © 2023 Quan Yuan and Qian He.