【作者】 陈涛；

【导师】 张琪昌；

【作者基本信息】 天津大学 ， 工程力学， 2016， 硕士

【摘要】 随着科学技术日新月异的发展和人们生活需求的不断提高,微机电系统凭借自身微、精、准的优势,逐步替代宏观系统更好地实现相应的功能,在愈来愈多的领域得到广泛重用。为了微机电系统能够又快又稳的发展,必须要有扎实科学的理论知识储备。当前阶段,针对应用最广泛的静电驱动微机电系统的研究,主要集中在理想设计结构的静态特性分析和动力学特性分析上,忽略了“牺牲层腐蚀”工艺的固有缺陷。然而,为了确保微系统的工作性能,工艺缺陷对微结构的静态特性、动力学特性及非线性行为的影响不容忽略。本文针对静电致动微桥系统的工艺缺陷问题,以真空封装的理想微桥、微拱和微缓冲结构为研究对象,对它们的静态吸合、动力学及其非线性行为进行理论分析,验证本文提出的“两侧加压双侧翘曲”结构改善含工艺缺陷微桥工作性能的可行性。在两端固支微梁横向自由振动方程的基础上,考虑惯性项、阻尼项、偏置电压提供的静电力激励项以及几何变形引起的非线性项,建立两侧加压静电致动微桥耦合系统的横向振动微分方程。工艺缺陷导致的几何变形以及为了改善微桥工作性能所设计的缓冲结构,在数学模型中均表现为微桥的初始形函数发生改变。应用伽辽金法将离散微桥的连续体模型,得到可行的单自由度模型,对其进行多尺度摄动分析得到微桥系统的振动响应方程。然后,分析不同初始形态微桥固有频率与直流偏置电压的关系、微桥的共振频率与初始形态控制参数的关系、微桥的幅频响应与初始形态控制参数的关系。精简出四种有代表性的微桥结构,分析其幅频响应关系,得到结论:微桥结构表现“软非线性”,共振频率漂移至相对更小的数值范围;双边褶皱结构削弱“软非线性”的功能性强于单边褶皱结构。而后,以理想微桥、微拱、双边褶皱缓冲结构为研究对象,分析拱高和板间隙、几何尺寸、直流偏置电压和交流激励电压幅值等主要控制参数对微梁动力学特性的影响,得到结论:对于微拱结构,拱高增大或板间隙减小,其共振频率减小,共振幅值增大,“软化”效应增强;对于几何尺寸不同的微梁,长梁的共振频率较小,共振幅值和非线性行为变化不明显,宽梁的共振幅值较大,共振频率和非线性行为变化不明显,薄梁的共振频率减小,共振幅值增大,“软化”非线性行为增强;直流电压增大,微梁的共振频率减小,共振幅值增大,“软化”非线性行为增强,交流电压幅值增大,微梁的共振幅值增大,共振频率和非线性行为变化不明显;双边褶皱结构的鲁棒性远强于微拱,接近理想微桥。更多还原

【Abstract】 Along with rapid development of science and technology and unceasing demand of life,MEMS has been applied in more and more fields for advantages of tiny,precise and accurate,gradually replacing macro-system to achieve equal function better.It is necessary to equip with massy theory for getting increasing development of MEMS.Researches on MEMS are mainly concentrated on the static analysis and dynamic analysis of ideal structures,ignoring the inherent defects of "sacrificial technology".However,in order to ensure the performance,it should not be ignored that process defects affect static and dynamic characteristics and nonlinearity.To resolve the problems in micro-bridges,this paper takes vacuum encapsulated ideal micro-bridges,micro-arches and micro buffered structure as objects.Some theory analysis has been done,for validate the feasibility of the "bilateral pressurized bridges".We get the governing equation of electrostatically actuated micro-bridges coupling system which is pressurizing on both sides from the transverse free vibration equation of clamped-clamped beams,considering inertia and damping term,electrostatic geometrical nonlinearity.Initial defects caused by process and buffered structure,designed for reducing the influence,is expressed as the initial shape.Analysis of the relationship between natural frequency and dc voltage,resonance frequency or amplitude-frequency response and control parameters of initial shapes of different micro-bridge has been done.Then,lean out four typical kinds of bridge structures,do some amplitude-frequency response analysis,concluded bridge structures performance "soft nonlinearity",resonance frequency drift to a smaller scale;bilateral fold structure weaken more "soft nonlinearity" than single fold structure.Then,take ideal bridge,arches,bilateral buffered structure as objects,analyze the influence on dynamic characteristics of highness of arch,clearance of plates,geometric sizes of bridges and offset voltage,concluded that: For micro-arches,its resonant frequency reduces,resonance amplitude increases,softening effect reinforces when the highness of arches increases or the clearance of plates decreases;for different geometric sizes micro-beams,resonance frequency of longer is smaller,resonance amplitude and nonlinear behavior changes not obviously,resonance amplitude of wider is bigger,resonance frequency and nonlinear behavior changes not obviously,resonant frequency of thinner is smaller,resonance amplitude of thinner one is bigger,"soften nonlinearity" of thinner is more obvious;when dc voltage increases,resonance frequency reduces,resonance amplitude increases,"soften nonlinear" is more obvious,when amplitude of ac voltage increases,resonance frequency and nonlinear behavior changes not obviously.更多还原