Size effect in transverse mechanical behavior of one-dimensional nanostructures

This paper develops the classical strain gradient elasticity theory to investigate the scale-dependent mechanical behavior of one-dimensional (1D) nanostructures. A governing differential equation with two scale parameters is derived, where the curvature of the deflection and the higher-order bending moment are introduced as a pair of additional geometrical constraint and natural loading. Emphasis is placed on the analysis of bending deformation, free vibration and buckling of cantilever nanowires or free-standing nanocolumns. Obtained results are compared with experimental data of carbon nanotube ropes and nanowires available in the literature and they agree well, showing that transverse mechanical properties of nanowires such as bending stiffness are scale-dependent. The model proposed also indicates that the evaluated natural frequencies and critical buckling strains exhibit noticeable size effects. Bending stiffness, natural frequency and buckling load increase as the nanowire diameter drops down. The influence of rotary inertia of cross-section is also analyzed.