基于骨缝承载机制的复合材料仿生连接结构失效机理研究

Advanced composite material is one of the most important structural materials in national defense, energy and manufacturing industry. However, the premature failure of composite bolted joint structures limit significantly the maximum strength of composite structures due to the stress concentration effect around the bolts. In this proposal, we present a composite bionic joint structure based on natural suture joint mechanics, in the purpose of enhancing the loading capabilities of composite joint structures. We propose manufacturing short-fiber reinforced composite bionic joint specimens using 3D printing technologies and two-stage co-curing method, developing experimental technologies to study the damage behavior and effect of geometrical parameters of composite suture joints, building numerical constitutive and damage model for the inhomogeneous, multi-stage and polyline joint interface, investigating the transition of damage mechanism of different types of interface geometries and analyzing the impact of geometry parameters on the fracture toughness of the composite bionic joint structure. Through this work, we will achieve understandings of the correlation between mechanical strength, damage mechanism and suture geometries, which is of great important for the design and optimization of novel high performance composite joint structures.

先进复合材料是国防、能源、制造业等尖端技术领域最重要的结构材料，但复合材料结构连接的过早失效则限制了其性能发挥。生物骨缝连接结构具有优异的力学承载特性，如能将其连接、承载机制应用于复材结构，可有效提高结构连接性能。为了研究短纤维增强复合材料仿生骨缝连接结构的承载与破坏机制，本项目将基于3D打印技术与图像相关分析技术，发展复合材料骨缝连接试件的参数化构建与变形破坏测试方法；建立可分析异质、多级、连续折线界面裂纹扩展与接齿破坏的仿生连接结构数值模型；研究骨缝连接结构在载荷作用下的不同破坏机制与机制转换过程；分析几何、层级与材料等参数对结构断裂韧性的影响。通过本项目研究，将揭示该类仿生连接结构的承载、损伤机制与主控参数影响规律，为该类结构的性能设计与强度评价提供理论依据。

本项目针对生物骨质连接的结构特点，采用分形算法建立了层级骨缝连接结构的参数化表征方法；依托该分形算法并借助3D打印技术，完成了不同层级、不同齿形参数条件下的仿生骨缝连接结构的建模工作；采用数字图像相关技术，观察了仿骨缝连接结构在外载荷作用下的变形与破坏过程。通过建立数值模型，进一步分析了不同层级、齿型参数条件下，仿生骨缝复合材料连接结构的断裂行为与断裂韧性；总结建立了一套可描述该类仿生结构变形破坏过程的数值计算方法；并将齿接结构的几何特征与其力学特性进行联系，分析了几何特征的对于结构承载特性的影响规律。相关建模方法与结构设计思路已被进一步用于航空复合材料连接结构的设计，在结构力学特征的设计方法上取得了显著成果。本项目共发表SCI论文3篇（中科院一区一篇、二区两篇），EI期刊论文2篇，会议论文2篇，资助项目参与人出国\境参会5人次。