基于同步高速红外/高速光学的金属绝热剪切原位实验及失稳机理研究

The dynamic failure of engineering materials like adiabatic shear localization under impact loading not only are issues of great concern in mechanics, but also are the significant engineering problems of defense and industrial equipment. Many key factors, such as adiabatic temperature rises and stress state, have an effect on the producing, evolution and propagating of adiabatic shear localization, which make the tradition problem to be solved difficulty. In this project, (1)The eight-element linear high speed infrared temperature measurement system will be utilized for establishing the first synchronous high speed infrared and optical experimental platform, which need to solve some the key technologies, such as time synchronization and flashlight shaded. (2)Combined synchronous experimental results (temperature and deformation) with microstructure evolution, new experimental phenomenon will be observed and the adiabatic shear localization behavior will be analyzed and its generating mechanism will be clarified, including the temperature effect; (3)A stress-state dependent adiabatic shear localization model will be developed and the stress state impacting on adiabatic shear localization will be clarified. The results of this project will be instructive for understanding the deformation and failure mechanisms of engineering materials under impact loading and promote the development of materials of dynamic mechanics behavior model, which has important scientific significance.

冲击载荷下工程材料的绝热剪切等动态失效不仅是固体力学的前沿科学问题，也是国防与工业高端装备中重大工程问题。由于绝热温升和加载条件(应力状态)等关键因素对绝热剪切的萌生、演化、扩展机理还不完全清楚，使得这一传统问题依然是学界研究的重难点。本项目：（1）基于申请人作为骨干成功研制的国内首台1×8线阵高速红外测温系统，通过攻克同步采集、遮光影响等关键技术难题，建立首个同步高速红外与变形观测实验平台；(2)结合微观结构演化与原位温度、变形实验，发现新实验现象，分析绝热剪切失稳行为，揭示温度对绝热剪切失稳机理的影响；(3)发展多向应力状态下绝热剪切失稳判据模型，阐明应力状态对绝热剪切失稳的影响机制。本课题的研究成果对于深入理解材料在冲击环境下的动态失效行为，进一步丰富和发展材料动态力学行为理论模型，具有重要的科学意义。

爆炸与冲击现象广泛存在于工业与国防军事领域，研究材料动态失效行为具有重要的科学与工程意义。绝热剪切失效作为冲击载荷下典型的动态失效行为，具有力热耦合的特点。而绝热温升和加载条件(应力状态)等关键因素对绝热剪切的萌生、演化、扩展机理还不完全清楚，使得这一传统问题依然是学界研究的重难点。..本项目围绕金属材料的绝热剪切失效问题，自主搭建同步红外测温和高速变形观实验平台，解决了新平台搭建过程中的时间同步性与光场串扰问题。利用同步实验平台，系统地开展了金属材料(TC4)不同斜槽角度的剪切压缩(SCS)和剪切拉伸(STS)试样的动态压缩和动态拉伸实验。通过高速红外测温系统和高速拍照获得了变形区域的温度变化和变形过程，探讨了温度对局部化变形的影响，分析了变形过程和失效机制，发现热软化可能并不是引起绝热剪切失效的主要机制。建立了临界剪切应变与失效机制的相图，认为损伤软化是导致绝热剪切失效发生的机制。利用图像处理技术获得临界剪切应变，结合有限元模拟得到失效位置的应力状态，建立了基于复杂应力状态的绝热剪切失稳判据(0.33<η<0.34)。本工作一方面丰富了材料动态力学性能的测试手段，另一方面对传统的热塑性失稳理论提出质疑，引发了该领域的广泛争论。本项目在 Mechanics of Materials、Journal of the Mechanics and Physics of Solids等高水平期刊发表学术论文4篇。