C/C复合材料界面率相关本构关系研究

Carbon/Carbon (C/C) composites have been widely used in aerospace applications due to their excellent mechanical properties. The interface between fiber and matrix plays a major role in determining the failure behavior and on the overall mechanical properties of C/C composites. The objective of the present work is to investigate the geometry, rate-dependent deformation behavior as well as damage initiation and propagation at interfaces in C/C composites with the development of analytical, experimental and computational methodology. The goal is to characterize the effect of the loading rate on the main deformation mechanisms such as the interface debonding and the interaction between each micro-phases at interface. In this study, the microstructure, bonding modes and failure/fracture mechanism at interfaces of C/C composites will be first studied by experimental observations. Further, the new interfacial rate-dependent model based on continuum mechanics approach will be developed to describe the kinematics of the cohesive surface in the interfacial micro-structures, the interface traction-separation relation as well as the rate-dependent damage evolution. Finally, the interface model is to be used in a numerical simulation of the nonlinear deformation and debonding behavior for the interfaces of C/C composites at various loading rates and that will be validated and improved from the corresponding rate-dependent experiments.

C/C复合材料是一种新型的结构材料，在航天航空领域得到了长足的发展。界面作为C/C复合材料力学及热物理特性传递的桥梁，它一定程度决定了C/C复合材料性能的发挥和材料破坏的类型并直接影响复合材料最终的整体宏观性能。本项目将结合理论分析、实验研究和数值模拟方法对C/C复合材料界面的细观结构、率相关变形和损伤机理进行深入研究，力求揭示不同加载率条件下C/C复合材料界面的脱粘行为及作用机制。通过本研究，首先利用实验手段弄清楚C/C复合材料界面的几何结构、界面的结合情况以及不同加载率条件下的断裂机理；在此基础上发展新的界面率相关本构模型，特别是从连续介质力学的角度认识界面的变形、服役过程中的界面几何结构特征的演变规律和效应，以及界面非线性率相关损伤演化规律和失效机理。最后借助数值模拟的方法预测不同载荷率工况下C/C复合材料界面的非线性变形和脱粘行为，进而和实验进行对比，进一步修正、完善该界面本构模型

本项目完成了复合材料增强相与基体间界面非线性率相关本构行为研究，发展并完善了复合材料界面微区的不可逆变形、脱粘以及摩擦等非线性力学行为。.1.在理论上提出了新的界面内聚力模型，成功用于预测纤维顶出过程中界面脱粘到滑移的非线性变形和失效特征，获得了不同温度条件下界面脱粘、摩擦滑移以及损伤失效特点和规律。.2.开展了加卸载条件下复合材料界面微区几何非线性、塑性以及损伤引起的不可逆脱粘变形行为研究，进一步发展了率相关弹塑性界面内聚力模型，成功地揭示了加载及卸载条件下复合材料界面脱粘的不可逆非线性行为。.3.开展了缎纹机织复合材料宏细观多尺度损伤失效行为研究，揭示了五枚缎纹机织复合材料不同尺度下的典型结构特征。在细观尺度下，主要考虑了纱线的波动，纱线之间搭接等特征；微观尺度下，主要考虑了纤维丝随机分布于基体内以及界面的几何特征。不同尺度下的数值模拟结果表明，细观尺度下，材料的主要失效模式为纱线截面开裂；微观尺度下，材料的主要失效模式为基体开裂和界面脱粘。.本项目研究成果对复合材料界面设计、改善组织结构，进一步提高力学性能与物理性能具有重要的指导意义