星载天线高精度索网结构的智能保型优化设计

Based on the application of the satellite antenna in the extreme environment for the background, and the study target of the on-orbit shape preserving of high precision cable net structure, the integrated optimization design method of shape memory material and cable net structure is used to the urgent solution to the difficult issues of thermodynamics and maintenance of cable net structure accuracy. Two aspects of scientific problems are launched around "the mechanical relaxation mechanism and modeling of the cable net structure under space environment effect " and " the coupling constitutive modeling of thermo ratcheting and creep for shape memory alloy": 1) to reveal the relaxation mechanism of cable net structure under the effect of bad space environment from the angle of the mechanical effect, and constructing the relaxation model of high precision cable net structure, 2) to research the coupling constitutive modeling method of thermo ratcheting effect and creep behavior of shape memory alloy to help the solution of the difficulty of the accuracy optimization for the shape memory cable net structure by the theoretical modeling and experiments, 3) to model the servo drive process of shape memory alloy under space thermo radiation, combining effectively with the relaxation model of cable net structure, to support the research target of shape accuracy preserving of the shape memory network structure in the whole life cycle. The work of this project is benefit for the solution of the design method, the major difficulty of design and the contradictory problems of the high precision cable net structure. It has clear academic significance and engineering value.

以工作在极端恶劣空间环境下的星载天线为应用背景，以高精度索网结构型面精度的在轨保型为研究对象，针对急需解决的复杂热力学和索网结构型面精度保持等难题，采用形状记忆材料与索网结构集成优化设计的方法，围绕“空间环境效应下索网结构松弛机理揭示与建模”和“形状记忆合金热棘轮效应与蠕变行为耦合作用机制及本构关系建模”两方面的科学问题展开研究：1）从力学效应出发揭示索网结构在恶劣空间环境效应下的松弛机理，构建高精度索网结构松弛模型；2）通过理论建模与试验，对支持形状记忆索网结构型面优化难点问题解决的形状记忆合金热棘轮效应与蠕变行为耦合本构建模方法进行研究；3）对空间热辐射下的形状记忆合金伺服驱动过程进行建模，与索网结构松弛模型进行有效融合，为形状记忆索网结构全生命周期的型面精度保持的研究目标提供支持。促进高精度索网结构型面精度设计方法、重大设计疑难与矛盾问题解决，具有明确的学术意义与工程价值。

在极端恶劣的空间环境下，索网天线的高精度设计要求天线具有良好的型面精度在轨调整能力。本项目将形状记忆合金植入索网结构，构成一种形状记忆索网结构，通过优化计算表明这种结构能够提高索网天线在轨型面精度。为了更加有效地实现温度驱动作用下NiTi记忆合金的有限元建模，本文采用应用较为广泛的Brinson模型，研究了杆单元的NiTi合金相变本构模型及有限元实现。并在此基础上开发实现形状记忆索网结构主动调节的杆单元有限元模型，完成了基于形状记忆拉索主动控制策略的索网结构型面精度优化设计。根据仿真数据，基于地面实验工况，对形状记忆拉索采用主动控制策略，实施了主动控制实验，验证形状记忆索网结构有限元模型的收敛性以及型面精度调节与优化的有效性。NiTi记忆合金材料在相变转换过程中存在相变棘轮效应，因此，基于对已有工作的归纳分析，本项目基于温度控制下的形状记忆效应NiTi合金相变棘轮行为的实验研究，将相变棘轮变形归结于不完全逆相变产生的残余马氏体变形，其演化方程均以累积马氏体体积分数为内变量，发展了一个能够较好描述相变棘轮行为以及相变过程非线性的本构模型。在考虑相变棘轮效应的条件下对形状记忆索网结构进行了优化，为形状记忆索网结构全生命周期优化设计打下了基础。为了索网结构空间环境下的优化，本项目计算了空间环境温度场，结合空间环境工况以及索网结构的长效载荷力学松弛模型，对形状记忆索网结构全生命周期的型面精度进行了优化设计。对形状记忆索网结构进行了高低温循环实验，实验结果表明，采用此方法能有效改进索网结构的型面精度。