缓冲结构对静电驱动微桥动力学特性的影响

Dynamic Characteristics of Electrostatically Actuated Micro-Bridges Affected by Buffered Structure

可动部件是微机电系统(MEMS)工作的关键,微桥作为主要的可动部件,其动力学特性引起了研究人员的广泛关注.即使是设计精准的微桥结构,也会因为残余应力而不可避免地改变初始形态,设计缓冲结构是减少残余应力影响的重要方法.基于欧拉-伯努利梁理论建立的微桥动力学模型,采用多尺度方法进行摄动分析,探讨初始形态、基板与极板间隙、直流偏置电压和交流激励电压幅值对系统共振频率和幅频响应的影响规律.结果表明:初始挠形、直流偏置电压和交流激励电压都具有软化效应,使共振频率漂移到较小的数值范围,且随着拱高增加或基板与极板间隙减小,软化效应增强,随着微拱曲率增大,软化效应减弱;缓冲结构可以削弱软化效应,缓冲结构的褶皱数量在2个以上时削弱效果变化不大,双侧翘曲缓冲结构削弱软化效应的能力强于单侧翘曲缓冲结构.

Dynamic behavior of movable components plays an important role in service behavior of micro-electro-mechanical systems（MEMS）. As a primary movable component,the dynamic characteristics of micro-bridges haveattracted the attention of scholars who are in the research field of MEMS. Inevitably,initial shapes of the finished bridges which have been perfectly designed change because of the residual stress. Designing buffered structure is an important method to reduce the influence of residual stress. A dynamics model of micro-bridge system based on Euler-Bernoulli beam theory was presented. The multi-scale method was used to carry out the perturbation analysis on dy-namic equations of micro-bridges. The effects of initial shape,the gap between based plate and electro-plate,the amplitudes of DC bias voltage and AC voltage on system’s resonance frequency and frequency-amplitude response were discussed in detail. Research shows that the initial deflection,and the amplitudes of DC bias voltage and ACvoltage show softening effect and shift the resonant frequency to a smaller range. The softening effect enhances with the arch height increasing or the gap decreasing,and weakens with the curvature of micro-arches increasing. Buffered structure weakens the softening effect caused by initial deflection,and the weakening effect barely changes when the number of buffered folds is more than two,and the ability of bilateral warping in weakening the softening effect is better than that of single one.