双光栅光谱仪光栅转轴的多目标优化

Multipurpose optimization for grating shaft of double grating spectrometer

双光栅光谱仪光栅转轴是用于固定和驱动两块共轴凹面光栅的重要零件,其工作过程中出现的变形与振动现象均可能对双光栅光谱仪最终的波长测量结果带来影响。依据双光栅光谱仪的工作原理和实际工况,确定其光栅转轴结构优化的主要目标为质心调整,轻量化,避免共振和减小凹面光栅的随机响应变形。为实现光栅转轴的多目标优化,首先在UG中建立凹面光栅、光栅转轴及其固定结构的三维模型,然后导入ANSYS Workbench进行模态分析与随机响应分析,并针对其计算结果展开多目标优化。优化后,光栅转轴回转部分的质心调整到回转轴上,总质量由0.606 30 kg减轻到0.539 43 kg,二阶固有频率从184.83 Hz增大到187.77 Hz,凹面光栅Z轴方向最大随机响应变形从33.394μm减小到27.147μm。目前市面上常见的有限元分析软件均无法直接实现结构的质心调整,作者将该目标的实现提前到三维建模过程当中,并保证在后续优化过程中,回转部分的质心只在其回转轴上移动,从而使质心调整和轻量化等其他优化目标同时实现,该处理方法具有广泛的借鉴意义。

Grating shaft of a double grating spectrometer is an important part which is used to fix and drive gratings, deformation and vibration of which both have effects on final measurement result. According to operating principle and working condition of the double grating spectrometer, centroid adjustment, light weight, avoid resonance and the decrease of the random vibration were chosen to be main goals in the optimization. First, three-dimension model of concave gratings, grating shaft and its fixture were built in UG. Then, they were imported into ANSYS Workbench, modal analysis and random vibration analysis were done. Finally, multipurpose optimization was done according to the result in last step. After the multipurpose optimization, centroid of the rotating parts was adjusted to the rotating axis. Its mass reduced from 0.606 30 kg to 0.539 43 kg. Its second natural frequency increased from 184.83 Hz to 187.77 Hz, and the maximal random vibration deformation on Z axis of concave gratings reduced from 33.394 μm to 27.147 μm. Centroid adjustment of structure could be realized directly by common finite element analysis software, the author achieved this goal when building three-dimensional models, and guaranteed that centroid of the rotating parts moved only on their rotating axis in optimization, so that centroid adjustment and light weight can be realized at the same time, which can be widely used in many other projects.