中文摘要：

不少微观实验已经证实，微尺度领域材料的力学性能存在尺度效应．文章以转动刚体、柔性微梁组成的刚柔耦合系统为研究对象，采用偶应力理论（又称Cosserat理论）研究微梁动力学特性的尺度效应，运用拉格朗日方程推导出系统考虑尺度效应的一次近似刚柔耦合动力学方程．仿真结果表明，较该文提出的一次近似耦合模型，传统的零次近似耦合模型在刚体作高速旋转时不能正确地描述微梁的动力学行为；尺度效应使微梁振动的振幅减小，频率增大．

英文摘要：

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 the model proposed in this paper, 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.