基于动力学性能的超高速摄影仪转镜的设计

摘要

A systematic design method has been proposed for studying the dynamic design of rotating mirror for ultra-high speed camera. With the finite element software, the numerical analyses of static, modal, harmonic responses and natural frequen-cy sensitivity for the preliminary-designed rotating mirror were done based on the static and dynamic theories. Some experiments were done to verify the results. The physical dimensions of the rotating mirror were modified repeatedly according to the results for designing a new rotating mirror. Then simulation and experiments of fatigue life for the new rotating mirror under alternating force were done. The results show that the maximum static stress is less than the yield stress of the rotating mirror material, which proves the new rotating mirror will not be subjected to static strength failure. However, the results of modal and harmonic response analyses indicate that the dynamic characteristic of the new rotating mirror can not meet the design requirement for the first critical speed is less than the service speed. In all the physical dimensions of the rotating mirror, the circum radius of mirror body and natural frequency are negatively correlated and the degree of correlation is maximal. The first-order natural frequency in-creases from 459. 4 Hz to 713. 6 Hz, the rate of change is 55. 3%, the first critical speed is up to 42 816 r/min, avoiding reso-nance successfully, and the fatigue strength of the new rotating mirror can meet the design requirement.%为探索超高速摄影仪转镜的设计,提出了系统性的转镜动力学性能设计理论和方法.结合静力学和动力学理论,利用有限元分析软件对初始设计的转镜进行静强度、模态、谐响应、固有频率灵敏度进行数值分析,并对数值分析结果进行试验验证,根据分析结果反复修改相应的转镜的结构尺寸并设计新的转镜,对新设计的转镜进行交变力疲劳分析和试验.结果发现,初始设计转镜的最大应力小于转镜材料的屈服强度,转镜不会出现静强度失效；转镜一阶临界转速落在工作转速以内,其动力学特性不满足要求；镜体外接圆半径与转镜的固有频率负相关且相关程度最高；新转镜的一阶固有频率从459.4Hz增大到713.6Hz,变化率55.3％,转镜的一阶临界转速达到42816r/min,成功地避开了共振点,且疲劳强度满足设计要求.