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1、国防科学技术大学硕士学位论文微倾斜悬臂梁在振动冲击载荷下的可靠性分析姓名：李孝涛申请学位级别：硕士专业：机械工程指导教师：陶俊勇2010-11国防科学技术大学研究生院硕士学位论文 第 I 页 摘 要 近年来，随着微机电系统（Micro-Electro-Mechanical Systems, MEMS）的迅猛发展和应用，MEMS可靠性问题已成为其实用化和产业化亟待解决的重要课题之一。在军事装备、航天等应用领域中，振动冲击载荷可能导致MEMS结构的断裂、粘附以及疲劳破坏，因此要求MEMS能够承受较强的振动冲击载荷。微悬臂梁作为MEMS的基本构件之一，广泛应用于各种微器件与微系统中，其可靠性问题直接
2、关系到MEMS的性能指标和功能。因此开展微悬臂梁在振动冲击载荷下的失效规律与特性研究，是MEMS可靠性研究领域的重要内容。 本文以某新型微陀螺的重要构件硅微倾斜悬臂梁为对象，从理论分析、有限元仿真、实验验证三个方面较系统地研究了其受振动冲击载荷下的可靠性问题。 （1）论文首先分析了微倾斜悬臂梁非对称横截面的力学特性，并进行了静力分析。理论分析和有限元仿真的结果验证了基于ANSYS软件仿真的微倾斜悬臂梁分析在工程中的可行性和有效性。 （2）运用梁结构弯曲振动理论，将悬臂梁-质量块结构简化为悬臂梁末端附加集中质量，得出了在简谐振动下的位移响应。利用有限元仿真对微倾斜悬臂梁进行了频响应分析，结果显示
3、：当振动频率低于微倾斜悬臂梁的固有频率时，微倾斜悬臂梁的应力水平和振幅都很小，满足可靠性要求；然而当振动频率接近其固有频率时，微倾斜悬臂梁末端位移急剧上升，可能导致质量块与基底发生粘附失效或同侧壁发生接触而破碎。 （3）基于准静态原理运用振动理论分析了微倾斜悬臂梁在冲击载荷下的动态响应，结果表明当冲击脉冲频率和微倾斜悬臂梁的固有频率相当时，微倾斜悬臂梁末端产生最大位移和根部产生最大应力发生是在强迫振动阶段。进一步利用有限元仿真验证了上述结论，研究表明微倾斜悬臂梁在冲击载荷下满足一定的强度可靠性要求，并可能产生另一个失效模式粘附失效。 （4）为验证理论分析和有限元仿真的有效性和正确性，设计了典型
4、的微倾斜悬臂梁微结构进行冲击实验，实验结果符合论文的理论研究和仿真分析结论，对微倾斜悬臂梁在不同加工工艺下的可靠性设计具有一定的指导意义。 综上所述，基于以上研究解决了微倾斜悬臂梁在振动冲击载荷下的动态响应问题，为提高某新型微陀螺的可靠性提供了理论依据，并对 MEMS 可靠性设计和质量控制有一定的借鉴意义。 关键词：微倾斜悬臂梁 振动与冲击 可靠性 MEMS 动态特性 有限元仿真 国防科学技术大学研究生院硕士学位论文 第 II 页 ABSTRACT Now with the rapid development of MEMS, the reliability has already becom
5、e to one of the key issue for its application and industrialization. We know vibration and shock is a typical service environment, Such as various vibration, impact and shock during transport and service, especially in the military and aerospace industry, taking more requirements to withstand strong
6、 loads. MEMS under vibrating and shock load may fail in several different modes including fracture, stiction, delamination, wear and so on. Of a cantilever which is the fundamental element of MEMS and is widely used in microstructures such as micro machined gyroscope, micro accelerometer, micro sens
7、or, and so on. In the paper the MEMS reliability in vibration and shock environment is studied by theory analysis, ANSYS simulation, and experiment by taking the example of the slanted micro cantilever, which is used in a novel micro-machined gyroscope. The main research content in the following asp
8、ects: 1. As the first step we analysis the bending spindle azimuth, spindle of inertia and bending stiffness of the unsymmetrical cross-section, then analyzed in the work process of the micro force and damping. Static analysis of the slanted micro cantilever by both of theoretical and ANSYS simulati
9、on validate the feasibility and accuracy of the application of ANSYS simulation of MEMS. 2. Assuming the micro cantilever-mass system is simplified to a cantilever attached centralized quality in the end. We calculate the intermittent vibration displacement response. By the ANSYS simulation result o
10、f using the modal and harmonic analysis function show that when the shock frequency is under the cantilever nature frequency, the stress level and vibration amplitude can achieve reliability requirement, however nearly inherent frequency range, both rising sharply, its displacement excessive may lea
11、d to occurrence of black and substrate adhesion failure or broken by a collision with the wall. 3. Based on quasi-static theory this paper studies on the dynamic response characteristic of the slanted micro cantilever under the shock by vibration theory. The result shows that when the shock load and
12、 the beam is equal to the natural frequency , the maximal displacement and stresses of slanted cantilever occurred in the force vibration stage, the impact of the value of about static load on the end of the beam of 1.707 times. Finite element simulation results validate the conclusion. We can get a
13、 conclusion that the main failure mode of slanted micro cantilever in the shock is adhesives failure, and it is strong in the strength reliability. 4. In order to validate the theoretical analysis and ANSYS simulation, based on exiting condition, we design a samples shock test. Furthermore the corre
14、ction of theory 国防科学技术大学研究生院硕士学位论文 第 III 页 analysis and ANSYS simulation is been validated by the experimental results. To sum up, this dissertation got a clear understanding of the dynamic response characteristic of the slanted micro cantilever under the shock .The results can be used for guiding t
15、he failure modes analysis of MEMS, and provided the rules for MEMS reliability design. Key Words: Slanted Micro cantilever，Vibration and Shock，Reliability，MEMS， Dynamic Characteristic，Finite Element Simulation 国防科学技术大学研究生院硕士学位论文 第 iv 页 表 目 录 表 1.1 MEMS同IC电路的差别分析 . 2 表 2.1 单晶硅材料特性 . 10 表 2.2 微倾斜悬臂梁静力分析理论和仿真结果 . 15 表 3.1 硅微倾斜悬臂梁的前四阶固有频率 . 27 表 4.1 冲击载荷下响应理论分析与仿真结果 . 38 表 5.1 微倾斜悬臂梁断裂失效个数 .
