Surface effects on nano-contact based on surface energy density.

In this paper, the two-dimensional nano-contact problem with the surface effect is systematically investigated based on Chen–Yao's surface elastic theory. The Fourier integral transform method is adopted to derive the contact stress and displacement fields of a half-space subjected to a normal triangle distribution force. The theoretical result shows that the surface energy density of the indented bulk substrate, as only one additional parameter, serves as an important factor to influence the contact properties in contrast to the classical contact models. The numerical show that only when the ratio of the contact width to the volume surface energy density to the shear modulus is equal, the difference between the theoretical prediction of surface effect and the classical contact solution without surface effect will be significant. This result indicates that when the surface effect is considered and the surface effect parameter is positive, the semi-infinite substrate will harden, which should be helpful for better understanding the size-dependent mechanisms of surface energy density at nanoscale. [ABSTRACT FROM AUTHOR]