薄壁多孔碳-碳复合材料栅极力学性能仿真与试验评价研究

Simulation and Experimental Evaluation of Mechanical Properties of Thin-walled Porous Carbon-carbon Composite Grid Electrode

  • 摘要: 薄壁多孔碳-碳复合材料栅极搭载离子推力器入轨阶段将承受较大的冲击与振动,存在栅极结构断筋、破损风险,严重影响离子推力器工作可靠性和服役寿命。针对10 cm口径离子推力器复合材料栅极研制需求,基于ABAQUS有限元仿真平台开展了10 cm口径碳-碳栅极力学特性分析,研究了总均方根值(Grms)为13.6g随机振动与1000g加速度冲击谱力学响应,与等口径传统钼栅极组件进行仿真对比分析,并开展了Z向冲击试验验证。研究表明:碳-碳栅极组件满足首阶共振频率大于100 Hz技术要求,无破坏性应力现象;碳-碳栅极较钼栅极抗冲击安全系数更高,1000g加速度冲击下安全裕度为钼栅极的2.53倍,冲击试验特征阻值项良好,调整栅极初装栅间距至0.70 mm可提升等口径离子推力器10.52%推力,通过栅极安装耳减震装置设计可进一步提升栅极动态稳定性。

     

    Abstract: Carbon-carbon composite grids possess advantages such as low density, excellent thermal stability, and a reduced ion sputtering rate. These characteristics make them an effective solution for enhancing the long-range performance, longevity, and high specific impulse of future high-power ion electric propulsion systems. The grid is typically a vulnerable component in ion thrusters, the thin-walled porous carbon-carbon composite grid mounted ion thruster will experience significant impact and vibration during the orbital stage, which poses the risk of broken ribs and damage to the grid structure, seriously affecting the reliability and service life of the ion thruster. To rationally design the carbon-carbon composite gate and understand the stiffness variation law of the composite grid, in response to the development requirements for the composite grid of a 10 cm diameter ion thruster, a mechanical characteristic analysis of a 10 cm diameter carbon grid was carried out based on the ABAQUS finite element simulation platform. The 13.6g Grms random vibration and shock response spectrum were investigated, and analyzed with the pole components through simulation. Z-direction impact tests were conducted for verification.Research shows that carbon-carbon grid components meet the technical requirements of a first-order resonance frequency greater than 100 Hz and have no destructive stress phenomena. Carbon-carbon screen grid has a higher impact safety factor than molybdenum screen grid, with a safety margin of 2.53 times that of molybdenum screen grid under 1000g acceleration impact. The characteristic resistance value of the impact test is good. Adjusting the initial grid spacing of the screen grid to 0.70 mm can increase the thrust of the equal caliber distance thruster by 10.52%.The design of the grid installation ear damping device can further improve the dynamic stability of the screen grid.

     

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