三维编织非周期结构复合材料冲击力学行为及破坏多尺度分析

Three-dimensional (3D) special-shaped braided composites with excellent entirety, high impact damage tolerance and fracture toughness play an irreplaceable role in the anti-impact field of aerospace and others. However, 3D special-shaped braided composites consist of many different features of meso elements, resulting in the characteristics of non-periodic structure. As such, it is difficult to predict the impact mechanical behavior. The present project is aimed at fabricating the non-periodic structural composites by regulating the unit numbers and sizes of four-step 3D braided preform. The meso solid models with different features are restructured by using CT scanning and statistical algorithm. Low velocity impact tests of 3D braided composites with varying braiding parameters, non-periodic type and distribution are conducted using the combination of the drop-weight impact equipment and the digital image correlation measurements. The impact deformation, absorbed energy and failure modes are evaluated, and the internal relationship between the diversity structure and the macro-mechanical properties are also discussed. The multi-scale Voxel-based method are established from the point of view of the element body. Considering the strain rate effect and the failure modes, the damage evolution and failure process of 3D braided non-periodic structural composites are simulated based on the continuum damage model. The objective of this project is to propose a reasonable mechanical analysis method for 3D braided non-periodic structural composite, and then to reveal the progressive damage and failure mechanism. Furthermore, it is expected to provide the theoretical basis for the parameter optimization and defect controls of special-shaped braided composites.

三维异型编织复合材料因其优异整体结构性、高冲击损伤容限和断裂韧性在航天航空等抗冲击领域具有不可替代的地位。然而，“异型”使三维编织复合材料结构呈非周期性，由多个不同性质的细观单元耦合形成，其冲击下的力学行为难以预测。本项目通过调控四步法三维编织预成型体的单元数量和尺寸制备非周期结构复合材料，采用CT扫描及统计算法重构不同性质的细观单元实体模型；利用落锤冲击与非接触全场应变测量相结合方法研究不同的编织参数、非周期结构类型及分布引起的冲击变形、能量吸收和破坏模式，揭示结构变异与宏观力学行为的内在关系；从单元体角度出发，构建基于Voxel单元的多尺度分析方法；基于连续介质损伤理论，考虑组分材料应变率效应及失效模式，模拟编织非周期结构复合材料的冲击瞬态损伤演化。本项目旨在建立适合三维编织非周期结构复合材料的力学分析方法，揭示其冲击积累破坏及失效机理，为异型编织构件的参数优化和缺陷控制提供理论依据。

三维异型编织复合材料因其优异整体结构性、高冲击损伤容限和断裂韧性在航天航空等抗冲击领域具有不可替代的地位。然而，“异型”使三维编织复合材料结构呈非周期性，由多个不同性质的细观单元耦合形成，其冲击下的力学行为难以预测。课题通过减纱工艺和RTM工艺制备了编织非周期结构复合材料。在此基础上，开展了Micro-CT扫描，建立了统计算法，重构了细观单元实体模型；采用落锤冲击装置测试了编织非周期结构复合材料（20°、30°和40°）在不同冲击能量下的力学性能；利用Micro-CT进行了断层扫描，研究了非周期结构类型及分布引起的冲击变形、能量吸收和破坏模式，揭示结构变异与宏观力学行为的内在关系；基于整体-局部损伤方法，构建了均质-细观混杂多尺度分析模型，建立了损伤本构模型，模拟了三维编织非周期结构复合材料冲击瞬态损伤演化。基于以上研究内容，揭示了三维纺织非周期结构复合材料冲击积累破坏及失效机理，为异型编织构件的参数优化和缺陷控制提供理论依据。. 通过项目实施，已发表高水平期刊论文19篇（SCI共12篇）；申请发表专利6项，授权2项。项目产生的结构设计和测试技术成果拓展至航空航天构件，部分已进入考核验证阶段。