卫星桁架结构跨尺度热—力耦合优化设计与分析

Thermal-mechanical Optimizing Analysis on Multi-scale Numerical Model for Composite Structure of Satellite

卫星飞行过程中,高精度测量设备的复合材料支撑结构经历多种温度环境,影响结构的热稳定性。为对其热学性能进行研究,综合考虑热—力耦合优化设计,首先,发展了复合材料热膨胀系数跨尺度数值模型。在微观模型中,通过建立代表性体积单元(Representative Volume Element,RVE)模型,由纤维热膨胀系数计算得到单向复合材料热膨胀系数;建立复合材料构件宏观模型,采用微观模型计算得到的热膨胀系数对宏观模型进行分析与计算。为验证复合材料热膨胀系数跨尺度数值模型的正确性,对复合材料管件的热膨胀性能进行了试验测试,测试结果与数值计算结果具有很好的一致性。其次,对卫星桁架杆件进行热稳定性优化设计与分析,综合考虑管件的热膨胀系数与刚度的约束条件,采用具有二阶收敛特性的共轭梯度法对复合材料构件的铺层进行优化设计,发展了复合材料桁架结构热—力耦合优化设计流程。最后,针对某卫星天线桁架支撑结构进行了定热膨胀系数设计与分析,结果表明采用跨尺度热—力耦合优化设计方法得到的热变形量远小于天线支撑结构给定的指标。该方法可用于卫星复合材料桁架结构热稳定性设计与分析。

When spacecraft works,it will suffer different temperature environments,while temperature difference will always introduce changes of shape and size of composite structures.However,some spacecraft parts need high dimensional stability to keep its right function.Till now,the mechanical properties of the composite have been widely studied,however,the thermal properties of composite and optimization of composite considering both thermal and mechanical properties are far from well studied.Composite tubes were optimized to a given coefficient of thermal expansion（CTE）,and the stiffness of those tubes was taken into consideration at the same time. Firstly, multi-scale numerical models were developed to calculate the CTE.In micro-scale mode,the CTE of unidirectional fiber reinforced composite was calculated by the fiber CTE through representative volume elements（RVE）. In macro-scale,a composite tube model was generated to predict both axial and transverse CTE of the tube based on the CTE computed by RVE.Composite laminates and tubes with given plies were analyzed and tested.Comparison between the predicted results and the experimental one verified the model, which made the foundation for the optimization mode.Secondly,optimization models for composite truss structure were created.The conjugate gradient method was adopted to optimize the plies of composite parts,and the thermal-mechanical optimizing method was developed.Finally,the satellite support truss structure was analyzed by the thermal-mechanical optimizing method. Analyzed results show that this optimized support structure and the whole antenna have an excellent thermal dimensional stability. The thermal-mechanical optimizing method can be used for thermal stability design and analysis of composite support truss structures.