电热驱动微直线位移机构运动特性分析与试验研究

发布时间：2018-05-31 15:07

  本文选题：微机电系统 + 微直线位移机构　； 参考：《上海大学》2015年博士论文

【摘要】：微位移机构是微机电系统(Microelectromechanical System,MEMS)的重要组成部分,承担微系统中运动和力的传递功能。微位移机构以致动器为动力源,经微杠杆、微齿轮或微棘轮等组件实现运动或动力传递。线性微直线位移机构可将致动器产生的微位移累积放大后输出。本课题针对微位移机构,开展了微位移机构的驱动机理、实验测试、理论建模和性能分析等方面的研究工作。完成的主要研究内容和成果如下:建立了电热致动器的瞬态温度分析模型和力学模型,利用有限差分法计算了致动器的瞬态温度,求解并实测了致动器在不同驱动条件下的输出位移,结果表明模型计算结果和实测结果一致。在充分了解MEMS加工方法和Poly MUMPs代工工艺特有设计方法的基础上,结合课题研究内容,设计了几类典型的摩擦式、啮合式微位移机构,并讨论了此类微机构设计时应重点考虑的相关问题和注意事项。建立了一套可行的微位移机构运动测试系统,通过对电热驱动摩擦式微位移机构的多次测试,获得了它们的相关运动参数。∏型约束和T型约束摩擦式微直线位移机构在不同驱动条件下实现了前推运动和后拉运动。频率对微直线位移机构的运动速度有影响,滑杆的速度随致动频率的增大而增大。设计制作的多种啮合式微位移机构经试验测试表明部分实现了预定功能,但性能尚待提高。建立了摩擦式微直线位移机构的运动分析模型,推导出了致动单元和滑杆的运动表达式,全面分析了驱动头和滑杆的相对运动以及滑杆仅在一组致动器驱动下即可产生前推和后拉两个方向运动的机理,同时分析了驱动条件和结构参数对滑杆运动方向的影响。实测了滑杆在不同驱动频率下的前推和后拉位移,实测与理论结果一致。理论分析表明,不同结构参数的摩擦式微直线位移机构,通过调节驱动频率,可改变滑杆的运动方向,致动单元的刚度和质量直接影响滑杆的运动形式。理论分析和实验证明用一组驱动实现滑杆的双向运动是可行的。针对典型微位移机构,从设计和使用两个方面分析了微位移机构的主要失效形式,设计阶段的失效主要来源于版图错误和违反设计规则而引起器件的功能失效,使用阶段的失效形式重点研究了致动器在交变温度载荷作用下的热疲劳失效。对微传动系统的设计提出了建议,并提出了改善微位移机构传动特性、提高其可靠性的措施。针对电热致动器在交流电作用下承受交变温度载荷而发生热疲劳失效的现象,分析了热疲劳失效机理。温度和应力计算表明,结构形式和施加的电压直接影响致动器的温度分布和应力大小,因最大应力小于屈服强度极限而不会发生应力引起的疲劳失效。测试了交流电作用下致动位移和循环次数的关系,实验结果和理论计算表明:温度低于脆性-韧性转换温度,电热致动器不发生热疲劳失效,否则在长期循环后会发生热疲劳失效。300~600℃的温度对电热致动器的工作最有利,在此温度范围内能够精确稳定地提供数千万次的致动循环。最后根据失效现象,分析了热疲劳失效机理,得出高温变形是引发热疲劳失效的直接原因。
[Abstract]:Micro displacement mechanism is an important part of Microelectromechanical System (MEMS). It bears the transmission function of motion and force in the micro system. Micro displacement mechanism so that the actuator is a power source, through micro lever, microgear or micro ratchet and other components to achieve motion or power transfer. Linear micro linear displacement mechanism can produce the actuator. In this paper, the driving mechanism of micro displacement mechanism, experimental test, theoretical modeling and performance analysis are carried out for micro displacement mechanism. The main research contents and results are as follows: the transient temperature analysis model and mechanical model of the electrothermal actuator are established, and the finite difference method is used. The transient temperature of the actuator is calculated and the output displacement of the actuator under different driving conditions is calculated and measured. The results show that the calculated results are in agreement with the measured results. On the basis of fully understanding the MEMS processing method and the special design method of the Poly MUMPs process, several types of typical friction formulas are designed. The meshing micro displacement mechanism is discussed and the related problems and attention should be considered in the design of such micromechanism. A set of feasible motion testing system for micro displacement mechanism is set up. By many tests of the micro displacement mechanism of the electric heat driven friction mechanism, the relative motion parameters of the micro displacement mechanism are obtained. The forward motion and back pull motion of the micro linear displacement mechanism are realized under different driving conditions. The frequency has an influence on the motion speed of the micro linear displacement mechanism, and the speed of the sliding rod increases with the increase of the frequency of the actuation. The experimental test shows that the predetermined function has been realized in some kinds of meshing micro displacement mechanism designed and produced, but the performance is still to be raised. The motion analysis model of the frictional micro linear displacement mechanism is set up, the motion expression of the actuating unit and the sliding rod is derived, the relative motion of the driving head and the sliding rod, and the mechanism of the two directions that the sliding rod is driven by a set of actuators only driven by a set of actuators are analyzed. The driving conditions and the structure are also analyzed. The effect of the parameters on the direction of the sliding rod motion. The forward and back pull displacement of the sliding rod at different driving frequencies is measured. The measured results are in agreement with the theoretical results. The theoretical analysis shows that the frictional micro linear displacement mechanism with different structural parameters can change the direction of the movement of the sliding rod by adjusting the driving frequency and direct influence of the stiffness and mass of the actuating unit. The theoretical analysis and experiment show that it is feasible to use a group of driving forces to realize the two-way motion of the sliding rod. According to the typical micro displacement mechanism, the main failure forms of the micro displacement mechanism are analyzed from two aspects of design and use. The failure of the design stage is mainly due to the error of the layout and the violation of the design rules. The thermal fatigue failure of the actuator under the alternating temperature load is emphatically studied in the failure mode of the use stage. The design of the micro transmission system is proposed, and the measures to improve the transmission characteristics and improve the reliability of the micro displacement mechanism are put forward. The mechanism of thermal fatigue failure was analyzed. The temperature and stress calculation showed that the structure form and the applied voltage directly affected the temperature distribution and stress size of the actuator, because the maximum stress was less than the yield strength limit and the stress induced fatigue inefficiency. The dynamic displacement and cycle under alternating current were tested. The relationship of the times, the experimental results and the theoretical calculation show that the temperature is lower than the brittle ductile transition temperature, and the thermal fatigue failure of the electrothermal actuator does not occur. Otherwise, the thermal fatigue failure at.300~600 C after a long cycle is most favorable to the work of the electrothermal actuator, which can provide a precise and stable supply of tens of millions of times in this temperature range. Finally, according to the failure phenomenon, the failure mechanism of thermal fatigue is analyzed. It is concluded that high temperature deformation is the direct cause of thermal fatigue failure.
【学位授予单位】：上海大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TH-39
，

本文编号：1960215