【作者】 刘双杰；

【导师】 郝永平；

【作者基本信息】 长春理工大学 ， 机械设计及理论， 2013， 博士

【摘要】 微机电(MEMS)惯性开关是对加速度的变化敏感并提供开关闭合动作的MEMS执行器,也称阈值开关、加速度开关或者g值开关。MEMS惯性开关不但体积小、响应快、能够捕捉微弱的信号而且很容易和外接电路融合,尤其适用于弹药的特殊环境。引信用MEMS惯性开关要求具有较强的抗过载性能、通用性、万向性等特殊要求,普通开关难以满足要求,且开关在工作过程中受多物理场耦合作用,其工作机理复杂,相关的设计理论不能满足需求,严重制约了MEMS惯性开关在引信中的应用。本文深入研究开关系统的静电力场、弹性力场、惯性力场、阻尼力场等多种物理场及耦合的基本问题,设计了两种MEMS惯性开关,分别满足引信的通用性和万向性需求。分析悬臂梁式的MEMS惯性开关在弹性力场与静电场耦合作用下出现的吸合效应,并求解出吸合电压；分析静电力作用下悬臂梁系统的有效弹性系数减小的负弹簧效应。提出计算静电驱动悬臂梁结构变形的三种方法,等效刚度法、模态叠加法和有限元反馈法,分别应用等效刚度法和有限元反馈法求解静电力作用下悬臂梁的变形特性,并比较三种方法的优缺点和适用性；建立了惯性力、静电力和阻尼力耦合作用下悬臂梁开关的动态模型。引入表征流体性能的雷诺方程,建立了悬臂梁的流-固耦合的挤压膜阻模型,推导出了在静电力、惯性力耦合作用时,悬臂梁压膜阻尼系数的计算公式。针对引信用惯性开关的通用性要求,设计了一种具有阈值可调功能的悬臂梁开关,该开关能够通过调节偏置电压以调节加速度阈值。基于静电驱动原理,推导出开关加速度阈值和偏置电压的关系；建立多物理场耦合下开关的系统级模型,对开关的准静态特性和动态特性进行系统级分析,研究可变阈值开关的基本性能。以500g为一档,调节加速度阈值范围为：500g～2500g,开关响应时间小于载荷持续时间的10%,开关接触时间大于300μs。针对引信用惯性开关万向性的要求,提出了一种多弹性支撑的环形分布式万向惯性开关。建立了开关的动力学控制方程；对开关进行静态特性分析,基于能量法中的卡式定律和胡克定律,推导出S型悬臂梁刚度的计算公式并进行有限元仿真验证,结果表明理论推导计算值和有限元仿真值的相对误差小于3%,S型折叠悬臂梁的理论公式推导正确；对开关进行动态特性分析,研究多弹性支撑的环形万向惯性开关的基本性能。开关在700g加速度阈值作用下,响应时间为0.12ms,两电极接触时间为35μs。介绍了多弹性支撑环形分布式MEMS万向惯性开关的加工工艺流程,研究了开关的检测技术；应用相移显微干涉法测量开关尺寸,通过尺寸检测得出悬臂梁的线宽误差分布及开关中可动电极和固定电极的间隙尺寸的加工误差范围,分析了尺寸误差对阈值加速度的影响；设计了一种冲击台试验用以测试开关的加速度阈值,该冲击台能够通过增加缓冲垫达到增加加速度脉冲宽度的目的；对开关进行了马歇特落锤实验,结果表明30000g加速度的高过载条件下,开关没有发生形变和断裂现象,仍然能保持良好的工作性能。更多还原

【Abstract】 The inertial MEMS switch is required to convert the acceleration signal which comes from the impact to the duration of the ON-state. The inertial MEMS switch is also called acceleration switch, threshold switch and G-switch. In particular, there is a need in the munitions fuze area for an ultra-miniature, fast-acting, inexpensive inertial switch that can be integrated with external circuit. The switch used in munitions fuze area need to follow some special conditions, against high overload, general-purpose, multi-directional sensing acceleration and so on, the general switch can not satisfy the conditions. At the time of the switch close, the MEMS switch worked in the multi-physics field, the work principle is complex, and the related design theoretics can not satisfy the devising demands yet, so the step of using MEMS switch in munitions fuze is slowed down badly. In this paper the theories of electrostatic field, elastic force field, inertial force field, damping field and the question of the multi-physics field are studied. Two kinds of switches are designed to satisfy the general-purpose and multi-directions sensing acceleration respectively in fuze.The pull-in effect is analyzed, which results from the coupling between the elastic force of micro-cantilever structure and the electrostatic force. The pull-in voltage is calculated. The negative spring effect is analyzed, that the effective spring constant will be decreased with the electrostatic force increasing. Three methods are presented for calculating the distortion of the micro cantilever under the electrostatic force, equivalent method, mode addition method and the finite element method with feed back. The advantages and disadvantages of the three methods are discussed, and the applicability of each method is analyzed. The distortion of the micro cantilever under the electrostatic force is simulated with equivalent method and the finite element method with feed back respectively.Combing the Renault equation which is used to describe the performance of the liquid with the micro-cantilever, the squeeze-film damping model is presented for the micro cantilever switch under the effect of electrostatic force, elastic force and inertial force coupling together. The squeeze-film damping coefficient formula for the cantilever switch is derived, and the analytical formula is presented to calculate the squeeze-film damping coefficient.To resolve the general-purpose question of the switch in fuze, a novel inertial switch with threshold adjusting is designed, the acceleration threshold can be adjusted by adjusting the bias voltage of the switch. Based on the electrostatic force driving, the liner relationship formula between the acceleration threshold and the bias voltage of the switch is derived. The systemic model of the cantilever MEMS switch is established in the coupled multi-physics fields and the static and the dynamic characteristic are researched based on the systemic model. The acceleration threshold is controlled from500g to2500g, adjusting500g every time, the response time is less than10%of the load duration, the contact time of the switch is greater than300μsTo resolve the multi-directional sensing acceleration question of the switch in fuze, the multi-elastic supported, annular MEMS inertial switch is designed. The dynamic differential equation of the movable electrode in switch is established. The static characteristic is researched, based on Castigliano’s2nd Theorem which is one of the energy methods and Hooke’s law, the spring constants of the folded serpentine micro-cantilever are derived and computed. The spring constant of the folded serpentine micro-cantilever is calculated by Finite element analysis using ANSYS software to validate the theoretic calculation. Compared with the Finite element simulation, the relative errors of the folded serpentine micro-cantilever are all less than3%. The results show that the formula deduction of the folded serpentine micro-cantilever is logical. The dynamic characteristics of the switch are researched by using finite element method. The response time of the switch is0.12ms and the contact time is about35μs.The technics process of the multi-elastic supported, annular MEMS inertial switch is introduced and the measurement techniques of the switch are researched. Based on the phase-stepping microscopic interferometry, the width of the cantilever and the gap between the two electrodes are measured and the error distribution is obtained, and the reason that the error will be effect the acceleration threshold is analyzed. The drop test is designed to test the acceleration threshold of the switch and the duration time of the acceleration can be adjusted by using buffer cushion. To test the capability of the switch that against high overload, Maehete test is used to offer3000g high acceleration, the test results show that the plastic deformation does not occur in the switch under the30000g acceleration and it can keep work commendably.更多还原