Surface buckling of a bending microbeam due to surface elasticity

In the present letter, we studied the surface buckling of a bending beam using the surface elasticity theory, and the corresponding buckling wave number was obtained analytically. It is found that surfaces with positive surface elastic modulus may buckle under compression, while surfaces with negative surface elastic modulus are possible to wrinkle irrespective of the sign of surface strain. By this method, various surface buckling phenomena happened in thin films or carbon nanotubes can be elucidated.