由于裂纹尖端的局部超弹性而导致的动态骨折不稳定性
Markus J Buehler1, Huajian Gao
1Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-272, Cambridge, Massachusetts 02139, USA. mbuehler@MIT.EDU
Nature
|January 20, 2006
概括
易碎材料的动态不稳定性导致裂纹表面随着裂纹速度的增加而变粗. 超弹性,或非线性应力-应变行为,控制了这种不稳定性,解释了裂传播现象.
科学领域:
- 固体力学 固体力学是什么
- 材料科学 材料科学 材料科学
- 计算物理 计算物理
背景情况:
- 脆性材料的裂传播表现出动态不稳定性,导致表面粗.
- 观察到的现象包括镜子,雾,和破裂表面在越来越大的裂纹速度.
- 现有的断裂理论往往忽略了裂纹尖端附近的非线性应力-应变关系 (超弹性).
研究的目的:
- 调查超弹性在裂传播过程中动态不稳定性的出现中的作用.
- 开发一种概括模型,解释裂不稳定性控制机制的竞争.
- 为破裂力学中有争议的实验和计算发现提供见解.
主要方法:
- 使用了大量并行,大规模的原子模拟.
- 采用一种材料模型,使从线性弹性向非线性行为的过渡成为可能.
- 开发了一个关于裂不稳定性开始的通用模型.
主要成果:
- 证明过弹性是动态不稳定性发生的决定性因素.
- 确定不稳定的开始是应力场和能量流机制之间的竞争.
- 模拟显示不稳定性是动态断裂固有的.
结论:
- 超弹性对于理解裂传播不稳定性至关重要.
- 概括模型为分析断裂表面形态提供了一个框架.
- 结果使不同的实验和计算观测在脆性骨折中协调一致.
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