20cm口径离子推力器力学特性模拟分析

Mechanical properties analysis of a 20cm diameter ion thruster

为了提升20 cm离子推力器的抗冲击性能,对现有结构开展了力学分析和试验验证。对栅极组件进行结构等效处理后,采用有限元方法分析了整机的模态和冲击响应谱。分析结果显示,栅极组件结构等效前后的分析结果对比差距8.3%~11.9%;推力器的3个轴向基频分别为246,248,336 Hz,栅极组件和中间极靴是离子推力器的力学薄弱环节并对整体结构稳定性具有重要影响;在冲击载荷1600 g下,栅极组件表面应力主要集中在小孔区边缘处,且形变也主要发生在小孔区;在采取刚度为1000 kN/m的减振措施后,栅极组件的整体形变位移降低了60%~82%。试验结果显示,在10~1200 Hz的低频扫描过程中,推力器3个轴向的基频分别为256,258,348 Hz,与仿真结果基本一致,采用减振措施后的20 cm口径离子推力器通过了1600 g的冲击试验。

To improve the anti-mechanical performance of the 20 cm diameter ion thruster, the mechanical analysis and experimental verification of its existing structure were carried out. After the grids were handled equivalently, the modal analysis and impact response spectrum analysis of ion thruster were carried out based on finite element analysis. The modal analysis results were validated by the fundamental frequency sweep test. Finally, the impact response of the thruster after adopting the damping structure was simulated and verified by experiments. The obtained results indicate that after the grids assembly being handled equivalently, the analysis results’ difference are about 8.3%-11.9%. The modal analysis result shows that the base frequencies of the thruster in the x, y and z directions are 246, 248 and 336 Hz respectively. The grids and middle magnet pole are the weak links in the mechanics of the ion thruster and affect the overall structural stability. The 1600g response spectrum analysis results indicate that 1600g, the surface stress of the grids concentrates on the rim of the aperture region, furthermore the deformation largely occurs in this region. When the vibration damping effect with the stiffness of 1000 kN/m is taken,the overall deformation of the grids is reduced by 60%-82%. Mechanical test results show that, during the lowfrequency scanning process of 10-1200 Hz, the base frequencies of the thruster x, y and z directions are 256, 258 and348 Hz respectively, basically consistent with the simulation results. Secondly, the 20 cm diameter ion thruster with damping measures passed the 1600 g impact test.