Abstract：Abstract: Many micro experiments have shown that the mechanical properties of materials at micro scale are size dependent. The dynamics of a rigid-flexible coupling system consisting of a rotating hub and a flexible micro beam is investigated in this paper. The dynamic characteristic of a micro beam is analyzed theoretically using couple stress theory (Cosserat theory). The governing equations of motion with the dynamic stiffening terms(referred as the first-order approximation coupling model) and the size effect term for this system are derived from Lagrange’s equations. Compared with proposed mode1，the traditional zero—order approximation model can not describe the dynamics of micro beam correctly when the hub is in high rotation speed. The size effect results in the descending of vibration amplitude and the increasing of vibration frequency of the micro beam..
2010, Vol. 31 
