20cm口径离子推力器栅极组件结构性能分析

Structural Analysis of Grids Assembly for LIPS-200 Ion Thruster

为了对20cm口径离子推力器栅极组件开展结构性能模拟分析,通过材料力学分析方法对栅极组件进行结构等效处理并进行验证,利用ANSYS有限元软件得到推力器的模态分析结果和栅极组件的模态振型,并开展基频扫描试验验证模态分析结果的正确性,最后模拟了推力器在1600g冲击载荷作用时,栅极组件的应力分布和形变结果。结果显示：将栅极组件等效为拱高不变且无孔的结构后,屏栅等效弹性模量为20.79GPa,加速栅等效弹性模量为89.43GPa;栅极组件表面的螺栓预应力大约在20~33MPa范围之间;模态分析结果显示,大于320Hz的振动频率时,栅极组件会出现较大的结构变化;通过10~1000Hz的基频扫描试验得到推力器基频在168Hz,分析结果 （185.23Hz）相比误差约10%;1600g的冲击载荷作用下,栅极组件边缘处最大形变达到约0.27mm,且表面边缘处的应力相对中心处较大,更容易发生破裂。

In order to perform simulation on the structural analysis of 20 cm diameter ion thruster grids assembly,the grids assembly was equivalently handled in structure by material mechanics and validated. Finite element software ANSYS was used to analyze the thruster mode,the mode vibration type,and base-frequency scanning experiment was performed to validate the mode analysis results. Also the stress and deformation of grids assembly were simulated under 1600 g shocking payload. The obtained results indicate that,after the grids assembly being handled equivalently,the screen grid equivalent Young＇s modulus is 20.79 GPa and the same parameter of the accelerator grid is 89.43 GPa. The prestressing force sensed by the bolt on the grids assembly is approximately in the range of 20~33MPa. With the vibration frequency greater than 320 Hz,larger structural deformation will occur in the grids assembly,by 10~1000Hz base frequency scanning experiments the thruster base frequency is found to be 168 Hz,which differs from analysis results（185.23Hz） by approximately 10%. Under1600 g of shocking,the maximum deformation on the grids assembly brim reaches 0.27 mm. The surface brim will sense larger force compared with the center region,and the fracture is easier to occur at the brim.