线振动MEMS陀螺结构振动非线性特性研究

针对一种线振动微机电系统(MEMS)陀螺结构的振动非线性开展研究,利用理论方法推导、有限元仿真和扫频数据拟合得到了陀螺结构的非线性系数,根据达芬方程推导计算出非线性迟滞效应消失的临界激励以及对应的振幅阈值,为陀螺结构设计提供了理论指导.实验结果表明:非线性迟滞效应消失点和理论值相吻合.     

基于硅微梳齿型谐振器的MEMS动态测试研究

在利用激光多普勒对硅微梳齿型谐振器多阶振动频率进行提取的基础上,结合频闪显微干涉测试技术对其谐振频率及其振幅进行了动态测试,并根据测试结果推导了谐振器的动态应力值.实验测试结果及应力推导结果与ANSYS的仿真结果相符合.     

基于最优S型曲线轨迹的硅片传输机器人末端振动抑制方法

针对硅片传输机器人末端低频振动问题,提出了一种基于最优S曲线轨迹的硅片传输机器人低频振动的抑制方法.该方法通过推导在参数化S型曲线输入条件下非线性时变系统的动态响应近似方程得到系统低频振动的振幅方程,并通过优化振幅方程中的S型曲线参数使得低阶振动振幅达到最小值,从而实现低频振动的抑制.首先对硅片传输机器人进行运动学、末端位置误差以及刚柔耦合动力学建模并进行动态特性分析.随后推导了在参数化S曲线输入条件下系统末端的时域动态响应方程近似解析解与振幅方程近似解析解,并根据硅片传输机器人自身的动态特性给出了最优S曲线参数计算方法.最后分别通过数值仿真分析与实验对该方法进行验证.实验结果表明,应用该方法后硅片传输机器人末端x方向的低频振动的振幅降低了53.9%,y方向的低频振动的振幅降低了45%.     

一种圆环结构MEMS谐振器设计

本文设计了一种圆环结构的高Q值MEMS压电谐振器,这种结构的谐振器可在单片RF系统上生产,减少能量损耗,提高Q值,而且不同频率的压电微谐振器的阵列的批量制造在单个芯片上,对其原理进行了分析,仿真,并做出实物进行测试,谐振频率在97.4MHz,Q值达到6499.15。     

K波段单片硅MEMS谐振器

介绍了基片集成波导技术和ICP深刻蚀微机械通孔阵列的硅基MEMS谐振器,通孔阵列和地平面形成不辐射介质波导,采用CPW电流探针与谐振腔进行信号耦合,在单层硅片上实现了平面电路与三维硅填充谐振腔的信号传输,得到低成本高性能可与平面电路集成的MEMS谐振器.谐振器工作于主模TE101模式,在片测试的Q值大于180,谐振频率21 GHz,与仿真结果吻合,芯片尺寸为4.7 mm×4.6 mm×0.5 mm.     

MEMS微电容式传感器的传感特性研究

针对传统的传感器无法进行长期健康监测的不足,研发出一套新型的基于MEMS的硅微电容式传感器.对所研制的MEMS传感器的静态传感特性和动态特性进行了理论分析和对比实验研究.结果表明:MEMS硅微电容式传感器在反复加卸载实验中,线性拟和度均在0.999%F.S以上,灵敏度系数为6.9840με/kN,其重复性误差为1.43%F.S;其动态传感特性与传统的加速度计吻合的很好.     

MEMS 器件IP 库及系统应

针对目前MEMS设计方法中系统分析不完善的现状,提出了将IP库单元应用于系统分析的方法.本文描述了已建立的MEMS微传感器件IP库单元的原型及库单元的结构和关键参数.以梳状微机械谐振器为例,使用SPICE语言调用已建立的IP库单元进行模拟分析,实现了MEMS器件和电路的系统模拟.     

Ka波段硅基MEMS滤波器

滤波器是微波毫米波电路中的一个重要部件,本文介绍了采用基片集成波导技术和ICP深刻蚀微机械通孔阵列的硅基MEMS滤波器.设计制作了MEMS滤波器的核心部件谐振器,测试结果显示该谐振器无载Q值大于180,频率误差控制在2%以内.以此为基础采用理论计算与实验设计相结合的方法设计了一个Ka波段硅基MEMS滤波器.滤波器中心频率为30.3 GHz,插入损耗1.5 dB,相对带宽5%.芯片尺寸为10.0 mm×2.8 mm×0.4 mm.     

静电梳齿微谐振器结构参数化设计

从理论上分析静电梳齿微谐振器的机械力学特性,给出了活动梳齿的横向谐振频率解析解。鉴于目前静电微谐振器模拟仿真中存在的问题,提出利用基于MAST语言实现的MEMS宏模块建立微谐振器系统级通用仿真模型,为验证外围电路提供了基础。仿真结果与理论模态分析相一致,验证了模型的有效性。通过谐振频率对结构参数的敏感性分析为优化谐振器性能提供基础,使工作模态远离其他高阶模态;合理安排激励电极,抑制一阶模态扰动。敏感性仿真表明:在横向振动微谐振器中,工作模态谐振频率随梁长的增加而减小;随梁宽的增加而增大;结构层厚度对横向振动频率没有影响;梳齿部分所有参数的变化造成频率的反向变化。     

弹塑性梁系统的动力学特性研究

研究了弹塑性梁系统的动力学特性.从弹塑性梁的非线性本构关系出发,同时考虑几何非线性,用虚功原理建立单个梁的动力学变分方程,利用假设模态法离散.在此基础上引入运动学约束关系,建立了弹塑性梁系统的刚-柔耦合动力学方程.对重力作用下的柔性单摆和双摆数值仿真结果表明,塑性应变引起横向变形绝对值增大和横向振动振幅衰减,在角加速度突变时塑性效应最为显著.     

分段阻尼隔振系统的动力学特性分析

针对传统线性隔振器在降低共振峰值的同时会牺牲隔振性能的矛盾,设计了一种含分段阻尼的隔振器.首先,采用移动凸轮变阻尼装置,通过凸轮廓线的设计使系统的垂向阻尼系数的受振动位移大小控制并呈现分段线性特征,分析了该装置的阻尼特性.然后将分段阻尼装置应用于隔振器中,建立了含分段阻尼的积极隔振系统模型及其动力学方程,通过能量等效原理求出了分段阻尼系统的等效线性阻尼系数,求解了简谐力激励下系统响应的理论解,并用四阶龙格-库塔法数值仿真验证了理论解的正确性.最后研究了分段阻尼隔振系统的动态特性,分析了主要参数对幅频响应特性与力传递率特性的影响.结果表明,通过合理的参数选择,分段阻尼隔振器可兼顾无阻尼隔振器与线性阻尼隔振器的优点,既能有效降低系统的共振峰值,又能保证高频区域的优秀隔振性能,为新型非线性隔振器的设计提供了理论依据.     

含间隙同步锥齿轮锁定后的非光滑动力学分析

针对周边环形桁架天线展开锁死后,分析齿轮副间隙由于空间冷—热环境交替对天线所产生的影响.因为整个桁架结构复杂,间隙种类众多,所以文中只研究一对同步直齿锥齿轮锁定后间隙的非光滑动力学行为.文中首先介绍了三种碰撞力模型,即恢复系数模型、Hertz接触力模型和非线性弹簧—阻尼模型,然后对物理模型进行简化得到动力学模型,最后建立了动力学方程.由于动力学方程中存在分段,直接求得解析解难度过大,文中直接采用数值仿真的方法进行分析,从仿真结果中得知含间隙的同步锥齿轮在外力的作用下整个系统会出现单倍周期、倍周期分岔和混沌等复杂的非线性响应.     

车辆系统的非线性行驶动力学响应

深入研究车辆在粗糙路面行驶而激励引起的非线性振动响应,对揭示复杂动态响应机理和提升动力学性能具有重要的理论意义与工程价值.首先,本文利用运动非线性机制,建立质心垂向平移和绕质心俯仰的两自由度车辆系统的力学模型,利用拉格朗日方程导出系统的非线性运动微分方程,分析自由振动系统的非线性回复力、势能曲线特性及平衡点稳定性.其次,针对自由振动系统,分析线性近似系统的频率比随参数的变化规律,又利用谐波平衡法分析非线性近似系统的幅频曲线特性.最后,针对强迫振动系统,利用数值方法得到系统的阻尼、路面波长及波幅对幅频响应曲线的影响规律.结果表明,新型车辆模型具有复杂非线性动力学特性,为行驶车辆系统提供参数设计和揭示振动机理提供理论参考.     

Compact damping models for laterally moving microstructures withgas-rarefaction effects

Compact models for the viscous damping coefficient in narrow air gaps between laterally moving structures are reported. In the first part of the paper, a simple frequency-independent first-order slip-flow approximation for the damping coefficient is derived and compared with a more accurate expression obtained from the linearized Boltzmann equation. The simple approximation is slightly modified and fitted to match the accurate model. The resulting simple approximation has a maximum relative error of less than ±6% at arbitrary Knudsen numbers in viscous, transitional and free molecular regions. In the second part of the paper, dynamic models for the damping force are derived, considering again gas rarefaction, by applying various boundary conditions. The damping admittance of the first-order slip-flow model is implemented also as an electrical equivalent admittance, constructed of RC sections, to allow both frequency and time domain simulations with a circuit simulator. The dependence of the damping admittance on pressure and gap displacement is demonstrated with model simulations. The accuracy and validity range of the model are verified with comparative numerical simulations of the Navier-Stokes equation. Finally, the damping coefficient in a lateral resonator is calculated using the compact model and compared with measured data with good agreement     

Nonlinear static and dynamic damped response of isotropic, elastic circular plates

Nonlinear static and dynamic response analysis of clamped-in and simply supported boundary conditions, and immovably constrained and stress-free edge conditions for circular plates of isotropic elastic material with damping, subjected to step pressure pulse excitation are presented. The Von Karman relations are used which are reduced to coupled nonlinear partial differential equations and solved by a one-term solution, applying the Ritz-Galerkin technique to the deflection equation. This yields an ordinary nonlinear differential equation in time. The nonlinear dynamic damped response is obtained by applying the ultraspherical polynomial approximation technique. Plots of static deflection to thickness ratio versus non-dimensional load for different boundary and edge conditions, and the effect of damping on the nonlinear dynamic response for different values of non-dimensional damping factor are presented.     

基于6DOF模型及动网格的动静压轴承刚度阻尼数值计算

针对传统雷诺方程求解三维油膜流场特性的局限性,提出基于6DOF模型及动网格的动静压轴承刚度阻尼计算方法.以具有典型结构形式的液体动静压轴承为例,通过加载6DOF自定义程序,采用非线性迭代方法计算外载荷作用下轴心轨迹的瞬态变化过程,得到轴颈在外载荷作用下的静平衡位置;通过嵌入UDF宏程序以动网格更新方法实现对轴颈在静平衡位置的扰动,求解Navier-Stokes方程得到轴颈扰动前后位置变化后的瞬态油膜力,利用差分法求得动静压轴承油膜刚度和阻尼,并分析了不同转速下轴承刚度和阻尼的变化规律.     

Modal analysis of nonlinear systems with classical and non-classical damping

In the dynamic analysis and design of structures and equipment, the behavior of various components beyond the linear range is often of interest. A nonlinear vibration analysis is time consuming, particularly if many configurations or loading conditions have to be considered in order to arrive at representative values for design. The selection of an efficient and yet accurate analysis procedure is therefore extremely important.

Two mode-superposition procedures are presented for the dynamic analysis of nonlinear structures with classical (proportional) and non-classical (non-proportional) damping. The nonlinearity at each time step is treated as a pseudo force. Undamped eigensolution and complex modes are used to uncouple the equations of motion for classical and non-classical damping cases. A recursive procedure based on the exact solution of the differential equation is used to obtain the modal responses. The advantages of the proposed method of computing the response over the existing integration techniques are: (a) the simplicity of the procedure, (b) a substantial reduction in computational time, (c) the possibility of using fewer modes to achieve the desired accuracy, and (d) the adaptability of the procedure to parallel processing machines which will further reduce the computational time.     

Simulation of Thin-Film Damping and Thermal Mechanical Noise Spectra for Advanced Micromachined Microphone Structures

In many micromachined sensors the thin (2-10 thick) air film between a compliant diaphragm and backplate electrode plays a dominant role in shaping both the dynamic and thermal noise characteristics of the device. Silicon microphone structures used in grating-based optical-interference microphones have recently been introduced that employ backplates with minimal area to achieve low damping and low thermal noise levels. Finite-element based modeling procedures based on 2-D discretization of the governing Reynolds equation are ideally suited for studying thin-film dynamics in such structures which utilize relatively complex backplate geometries. In this paper, the dynamic properties of both the diaphragm and thin air film are studied using a modal projection procedure in a commonly used finite element software and the results are used to simulate the dynamic frequency response of the coupled structure to internally generated electrostatic actuation pressure. The model is also extended to simulate thermal mechanical noise spectra of these advanced sensing structures. In all cases simulations are compared with measured data and show excellent agreement - demonstrating 0.8 and 1.8 thermal force and thermal pressure noise levels, respectively, for the 1.5 mm diameter structures under study which have a fundamental diaphragm resonance-limited bandwidth near 20 kHz.     

基于非线性消振器的空间结构被动振动抑制

研究了空间结构振动抑制的被动非线性消振方法.提出了适用于空间环境的非线性消振器结构及动力学模型,该结构通过引入磁力实现空间环境下航天器结构的振动抑制.然后,从理论上建立了含有非线性消振器的空间悬臂梁结构动力学模型,并通过Galerkin截断及数值分析方法分析了瞬态激励下非线性消振器对空间悬臂梁结构的被动振动抑制效果.仿真结果表明,该被动非线性消振器对系统的能量耗散率可以达到92%,可以实现非常好的振动抑制效果,能够适应空间环境,并提高航天系统的可靠性.     

路面激扰与电磁激扰下电动轮车辆系统非线性全局动态特性研究

为研究电动轮车辆系统在路面 电磁联合激励下的非线性振动特性,并挖掘参数与初始条件协同作用下系统全局动力学信息,建立了计及悬架系统和轮胎的非线性弹簧力和阻尼力的电动轮车辆系统两自由度1/4垂向振动非光滑非线性时变动力学模型,考虑外部激励的谐波性和随机性以及电磁激励的分段周期性,得到了含谐波性、随机性和周期性的复杂外激励模型,分析了驱动电机转速与多初值的关联性对系统动力学共存行为及其分岔的影响规律,研究了共存运动的多样性及其吸引域的拓扑构型,揭示了转速对系统全局动力学稳定性的影响机理.结果表明：电机转速与多初值协同作用诱发系统出现多样性的共存运动,共存运动吸引域的拓扑结构复杂多样,部分共存运动的振动幅值可能较大亦可能很小,其全局动力学稳定性差异较大.电机转速与初值的协同作用对电动轮车辆系统非线性振动和全局动态特性的影响不予忽视.本文研究对电动轮车辆系统的动态性能改善和结构优化具有重要的理论意义和工程价值.