压力浸渗法金属z-pin增强碳纤维/铝复合材料层合板的层间断裂行为及界面调控机理

Carbon fiber reinforced aluminum matrix composites (Cf/Al) of high specific strength and specific stiffness are of great importance in miniaturization and lightweight design of aeronautics and astronautics structures, however, delamination fractures in Cf/Al composites laminates are common during their proceeding by pressure infiltration casting and subsequent machining. In order to solve this problem,the present project for the first time introduces the novel concept of z-pin technology to metal matrix composites area, focusing on designing and fabrication of z-pinned Cf/Al composites laminates. The current work is set to investigate some thermodynamics and kinetics factors which impact the interface mesostructure between z-pins and laminates and clarify the relevant regulating and controlling mechanism with the z-pin/laminate interface mesostructure. In the present project the shear-delamination behavior of z-pinned Cf/Al composites laminates will be observed in situ and their deformation and fracture will also be investigated through the computer simulation to obtain the relevant principle and bridging mechanism of metallic z-pin in Cf/Al composites laminates. The effect of the z-pin/laminate interface mesostructure on the delamination fracture behavior of z-pinned Cf/Al composites laminates will be analyzed. A meso mechanical model will be developed to describe the constitutive relation between z-pin bridging force and delamination displacement of the laminates. An optimized design method for interlaminar and in-plane mechanical properties of z-pinned Cf/Al composites is to be built up on the basis of regulating and controlling the z-pin/laminate interface mesostructure. A theoretical fundamental and basic data can be found through the current work, which can be helpful for structure design of Cf/Al composites with z-pin technology. Additionally, the conduct of the project will have an important significance and great value to promote the material-structure integration forming of the Cf/Al composites.

高比强度和高比刚度的碳纤维/铝复合材料(Cf/Al)对航空航天结构小型化、轻量化设计具有重要意义，但在其压力浸渗铸造成型及机械加工过程中层合板结构易发生分层。为解决该问题，本项目首次将z-pin技术概念应用于金属基复合材料领域，设计制备金属z-pin增强Cf/Al复合材料层合板，拟通过分析影响z-pin/层合板界面结构形成的热力学和动力学因素，阐明界面结构调控机理，分析层合板的原位层间剪切变形行为，并对层合板的层间断裂过程进行数值模拟，获得z-pin/基体界面结构和复合材料层间断裂行为相关性规律，探明金属z-pin对复合材料层合板的桥联机制，建立z-pin的细观力学模型，确立Cf/Al复合材料层间及面内力学性能的界面调控设计方法。本项目的实施将为z-pin技术应用于Cf/Al复合材料结构设计提供理论依据和基础数据，对促进Cf/Al复合材料的材料-结构一体化成型具有理论意义和实际价值。

高比强度和高比刚度的碳纤维/铝复合材料(Cf/Al)对航空航天结构小型化、轻量化设计具有重要意义，但在其压力浸渗铸造成型及机械加工过程中层合板结构易发生分层。为解决该问题，本项目首次将z-pin技术概念应用于金属基复合材料领域，设计制备金属z-pin增强Cf/Al复合材料层合板。本项目采用压力浸渗法成功制备了高质量高致密z-pin增强Cf/Al复合材料，揭示了z-pin/层合板界面反应特征，并探讨了z-pin/层合板界面状态和性质的控制性因素及其影响机理。系统研究了z-pin直径、面密度等多因素对多种条件下层间力学性能及面内力学性能的影响规律。明确了z-pin在层间剪切破坏过程中变形行为，建立了z-pin层间强化模型，揭示了Cf/Al复合材料层间剪切的z-pin强化机理。运用有限元分析软件Workbench（ANSYS）建立了双切口z-pin增强碳纤维/铝复合材料层间剪切模型。结果如下：.Z-pin金属针(不锈钢)与铝基体发生界面化学反应，形成连续界面反应层FeAl3，金属针/铝界面形成强界面结合。随加入金属针直径的增加，FeAl3界面反应层厚度降低。.双切口法层间剪切测试表明，加入0.3~2.7vol.%，直径0.3~0.9mm的金属针后，z-pin增强Cf/Al复合材料的层间剪切强度提高了0.7~2.3倍，剪切断裂功提高了8~20倍，并随金属针体积分数和直径的增加而增大。.短梁法层间剪切测试表明，加入0.25~1vol.%，直径0.3~0.9mm的金属针后，z-pin增强Cf/Al复合材料的层间剪切强度下降1%~14%，剪切断裂功提高了31~89%，并随金属针体积分数和直径增加而增大。.Z-pin增强Cf/Al复合材料弯曲强度在加入0.25~1vol.%，直径0.3~0.9mm的金属针后，下降2%~25%；弯曲强度随金属针体积分数的增加而降低，随金属针直径增加而增大。.SEM电镜原位观察表明，z-pin增强Cf/Al复合材料的层间剪切破坏机理是z-pin/层合板的界面裂纹萌生并发展，z-pin的层间强化机理是z-pin自身在弹性变形时承担剪切应力和在塑性变形分散剪切应力两个方面作用的结果。这与有限元模拟分析结果一致。.本项目的实施将为z-pin技术应用于Cf/Al复合材料结构设计提供理论依据和基础数据，对促进该材料的材料—结构一体化成型具有理论意义和实用价值。