基于流动-应力数值模块同步耦合的大厚度复合材料结构固化行为研究

The existing technical approaches hardly give the accurate cure-induced behavior of composite structures with large thickness, leading to the difficulty for proposing effective scheme to control cure-induced stress-distortion during manufacturing. One of key solutions to this limitation is to promote numerical simulation to obtain the better estimation precision in the cure-induced stress and distortion. Accordingly, this project intends to improve the current flow-compaction numerical module by considering compressibility and non-mechanical strain of composites system as well as the change of Biot coefficient before gelation, and integrate flow-compaction and stress/deformation numerical modules in line with continuous evolution of cure-induced stress. Subsequently, multi-field coupled numerical simulation method based on the synchronously coupled flow-stress module will be established for predicting cure-induced behavior of composite structures by means of experimental measurements and multi-scale modeling for predicting properties, in combination with the secondary development platform provided by the Finite Element software. Meanwhile, the comparison between numerical and experimental results will be carried out to calibrate and validate the newly proposed numerical simulation method via the collaboration of point pre-cure FBG sensor positioning technique and numerical prediction. Furthermore, the analytical solutions for the overall cured-induced distortion of L-shaped and U-shaped composite structures will be derived to support the newly developed numerical simulation method. The hybrid analyses using numerical and analytical approaches will be employed to reveal the formation mechanism of cure-induced stress and distortion of composite structures with large thickness and complex geometry. The achievements of this project will be helpful on the manufacturing scheme design of composite and facilitate the application of composites with large thickness in various fields.

现有的技术手段难以准确描述大厚度复合材料结构的固化行为，无法提供有效的工艺应力-变形预防措施。解决这一问题的关键是在于完善数值模拟方法，提高固化应力和变形的预测精度。本项目拟考虑凝胶前复合材料体系的可压缩性、非机械应变和Biot系数的变化，改进现有的流动-压实模块；基于固化应力连续发展的现实，集成流动-压实和应力位移模块；结合实验测试和多尺度模型性能预测技术，借助有限元软件的二次开发平台，建立基于流动-应力模块同步耦合的多场耦合下复合材料固化行为数值模拟方法；同时将FBG传感器局部预固化技术和数值模拟结合，通过数值-实验结果混合对比方式对所提出的数值模拟方法进行校正和验证；此外，发展L型和U型结构整体固化变形解析式，作为数值模拟方法的辅助手段，通过数值-解析混合分析方式揭示复杂构型大厚度复合材料结构应力和变形的形成机理，指导结构工艺制造方案的设计，推动大厚度复合材料结构在各领域的应用。

现有的研究手段难以准确描述复合材料结构的固化行为，无法提供有效的工艺应力-变形预防措施。解决这一问题的关键是在于完善数值模拟、解析和实验方法，明晰固化残余应力和变形的形成机理。本项目借助有限元软件的二次开发平台，建立了多场耦合下复合材料固化行为的数值模拟方法，并引入FBG技术实时监测固化过程中复合材料内部的温度和应变变化。同时，基于剪力滞理论发展了L型和U型复合材料结构整体和局部固化变形解析式，分析了曲型复合材料整体和局部回弹角幅值的影响因素，并提出了一套简单方法预测复合材料结构回弹角的方法，该方法基于组分材料的性能，结合多尺度性能预测方法就可以理论预测曲型复杂铺层复合材料的回弹角。此外，以环氧树脂为研究对象，基于顺序耦合热传导-固化和应力位移模块的模拟方法，选择合适的实验方法测试环氧树脂固化性能，引入相关假设，推导与热传导-固化和应力位移模块相关的树脂固化性能参数值和模型。在项目的资助周期内，在复合材料固化行为的监测、仿真和固化性能表征等方面取得了一定的进展和突破，为复合材料结构的应力-变形控制方案提供计算和监测工具，研究成果预计将在我国航空航天、船舶和风电用复合材料有着非常重要的基础研究意义。