高精度太赫兹碳纤维复合材料反射面夹层结构特性研究

Terahertz band is one of the most important bands which is used to observe early distant objects, cold dark matters, interstellar dust and molecular gas clouds in the universe, and so on. And an ideal terahertz observatory site is generally located in the extreme environment with low water vapor content, low temperature, low pressure and large spatial and temporal temperature difference. So it is important to maintain the surface accuracy of the primary reflector to ensure the observation efficiency of terahertz telescope in such sites. So Carbon Fiber Reinforced Composites (CFRP) sandwich structure comes to be a more reasonable choice in reflector panels with features of lightweight, high strength, low expansion and designability. However, some special effects to the performance of CFRP panel will be caused by the extreme environment, such as reflector icing, surface shape error caused by the temperature gradient in the direction of thickness, and internal interface damage caused by thermal cycling loading and so on. So it is necessary to proceed the structural optimization for the sandwich structure. This project takes typical terahertz telescope specifications as input conditions, and a model for panel of performance prediction is accurately established by the method of numerical simulations and experiments. The study of temperature response, thermal deformation and thermal fatigue life of panel models with different core constructions are carried out and the performances of the panel models are comprehensive evaluated finally. This study will accumulate important technical experience for terahertz antenna system design and engineering construction.

太赫兹波段是观测早期遥远天体、宇宙中低温物质、星际尘埃和气体分子云等的重要波段，而理想的太赫兹观测台址一般都选在水汽含量极低的极端环境，具有极低温、低压和季节性温差大的特点。在这样的台址观测，维持天线主面的面形精度是保证太赫兹望远镜观测效率的重要前提，因此碳纤维复合材料夹层结构凭借其轻质高强、低膨胀和可设计性强的特点，成为了天线比较理想的选择。然而太赫兹台址环境会对复合材料面板的工作性能造成一些特殊影响，主要有反射面结霜、厚度方向温度梯度引起的面形误差和内部界面的热疲劳损伤等问题，需要通过针对面板夹层结构的优化设计来解决。本申请项目拟面向太赫兹望远镜的应用需求，利用数值仿真和试验的技术手段，建立精准的夹层结构面板的性能预测模型，开展针对不同夹层结构面板温度响应、热变形和界面热疲劳寿命等方面的研究工作，最后还对其性能进行了综合评估，为太赫兹天线系统的设计和工程建设积累重要技术经验。

维持天线主面的面形精度是保证太赫兹望远镜观测效率的重要前提，因此碳纤维复合材料夹层结构凭借其轻质高强、低膨胀和可设计性强的特点，成为了天线比较理想的选择。然而太赫兹台址极端环境会对复合材料面板的工作性能造成一些特殊影响，主要有反射面结霜、厚度方向温度梯度引起的面形误差和内部界面的热疲劳损伤等问题，需要通过针对面板夹层结构的优化设计来解决。本项目面向太赫兹望远镜的应用需求，开展针对不同夹层结构面板温度响应、热变形和界面热疲劳寿命等方面的研究工作。项目首先通过在阿里地区的环境实验数据拟合了面板热力学模型参数，仿真了面板实时的温度分布及面形精度，优化了面板结构。发现铝蜂窝面板整体温度较为均匀，但热变形特性不佳；而全碳结构面板的温度梯度较大，但热稳定好，所以面形精度仍然优于铝蜂窝面板。其次测试了大温差工况下面板中胶层的热应力分布，测试了三种材料组合界面的应力水平，利用疲劳仿真的方法预测了面板的使用极限。最后试制了原型面板，并对其热变形性能进行了综合评估，测试结果表明：面板在+40℃环境下的面形精度为7.2微米 rms，在-40℃环境下的面形精度为7.3微米 rms，实现了“零”膨胀的热力学特性。