大口径胶粘主镜装调的有限元分析

Alignment of Large Aperture Gluing Primary Mirror with Finite Element Method

文章针对采用胶粘工艺的轻量化大口径主镜装调过程中涉及的几种典型受力状态进行了研究。首先,建立了包含胶层的主镜组件精确的有限元模型,并考虑了胶斑的径厚比较大时对其弹性模量参数的修正;其次,利用有限元法结合Zernike拟合程序分析了强迫位移、1gn自重、均匀温升、胶层收缩、主镜两点支撑检测状态下主镜面形的变化,其中采用温度载荷等效的方法对胶层收缩在Patran/Nastran环境下进行了模拟。结果表明主镜组件自重变形和热变形对面形影响较小,而强迫位移0.01mm、胶收缩1%产生的应力、以及主镜两点支撑检测时对主镜面形影响显著。此外,对主镜两点支撑状态进行了试验检测,其面形变化与分析结果吻合。

In the alignment process of lightweighted large-diameter primary mirror（PM） with adhesive technology, several typical stress states involved in the process are studied. First, an accurate finite element model of a primary mirror assembly （PMA） is built, with considering of the detail of adhesive layer, and the correction to the layers＇ elastic modulus parameters when diameter-thickness ratio （DTR） is large; secondly, the finite element method and Zernike fitting procedure （ZFP） are used to determine the influences of 1） forced displacement, 2） lgn inertial load, 3） uniform temperature rise, 4）shrink of adhesive layer, and 5） two supporting points when check the surface quality of the primary mirror. Moreover, an equivalent temperature load method is introduced to process the adhesive shrinkage effect in the Patran/Nastran environment. The results show that in the conditions of 2） （forced displacement of 0.01mm） and 3） （uniform temperature rise 1K）, the surface deformation of PM is ignorable, however in the other conditions the PM surface shape changes significantly. In addition, test of the condition 5） is carried out, and the test result is in line with the analysis result. Methods provided herein have significance for improving the large-diameter lightweight PM design and alignment.