Elasticity theory of ultrathin nanofilms

A self-consistent theoretical scheme in the framework of continuum mechanics for describing the elastic behavior of ultrathin nanofilms (UTNFs) was proposed in this paper. The lower symmetry of an UTNF compared to its bulk counterpart was taken into account, as a result, the additional elastic parameters were introduced to model the elasticity rigorously. The current theory was applied into two elastic systems and allows us to achieve an excellent agreement with experimental results. More importantly, the surface elastic parameters used to fit the experimental results are physically reasonable and in close agreement with those obtained from experiment and simulation. This fact suggests that the additional elastic constants due to symmetry breaking are of great importance in theoretical description of the mechanical properties of UTNFs.