Dynamic Analysis Considering Molecular Force Of Electromechanical Integrated Electrostatic Harmonic Drive

Electromechanical integrated electrostatic harmonic drive is a novel generalized composite drive, which integrates control, drive and transmission. By the harmonic deformation of flexible ring, the transfer and transform of motion is realized. With the decrease in the size of the system, the effects such as the van der Waals and Casimir forces is more and more obvious. Dynamic performance of the micro system will change accordingly.In this dissertation, a static model of the electromechanical coupled continuous body considering molecular force is presented. The equations of the radial displacements of the flexible ring and its output torque for the drive are given. The effects of van der Waals or the Casimir force on the radial displacements of the flexible ring and the output torque are analyzed. The results show that the effects of van der Waals and the Casimir force on the radial displacements of the flexible ring and the output torque can not be ignored in certain conditions.Using the electromechanical coupled dynamic equations of the flexible ring, effects of the van der Waals force and the Casimir force on the natural frequencies and the vibrating modes of the flexible ring are investigated. Based on the mode superposition method, the forced response equations of the flexible ring for the drive to the electric excitation are deduced under considering electrostatic and the molecular forces. Using the equations, the effects of the van der Waals force and the Casimir force on the forced responses of the systerm are investigated. Results show that in some cases, effects of the molecular force on the vibrating modes and the forced responses of the systerm are important.When nonlinearity of electric field force and van der Waals force is considered, by perturbation method, the effects of the van der Waals force on nonlinear free vibration, forced response far from natural frequency and near to them are discussed. The resules show that the effects of the van der Waals force on nonlinear vibration of the system should be consider in some cases.The solid model of flexible ring is given with Pro/ENGINEER software. Static displacement and vibration frequency of the electromechanical coupled flexible ring under considering the molecular forces are simulated with Pro/MECHANICA and ANSYS, and compared with the theoretical analysis, which demonstrates the correctness of theory analysis.