Clarication of fracture mechanism in front of crack tip with in-situ STM observation and molcular dynamics analysis

本研究由以下分析方案和实验方案组成：分析方案为断裂的微观分析开发了以下新方法。(1)提出了分子动力学与连续力学的混合方法。(2)用这种方法分析了小尺度屈服条件下裂纹尖端前的断裂过程区。结果表明，该方法能从原子行为水平上分析断裂过程，并能分析细尺寸结构，克服了分子动力学方法的不足。(3)将该方法应用于一个摩擦学问题，得到了新的结果。实验项目用原子力显微镜观察了疲劳过程。(4)通过原子力显微镜观察和蚀坑法晶体分析，阐明了疲劳过程。提出了一种新的疲劳机理模型。

This research consists of the following analytical project and exprimental project.ANALYTICAL PROJECTThe following new method was developed for microscopic analysis of fracture.(1) The hybrid method between molcular dynamics and continuous mechanics was proposed.(2) Using this method, we analized a fracture process zone in front of a crcak tip under small scale yieldinbg condition. It is concluded from this method that the fracture process can be analized in level of atom behavior and a finete size structure can be analized.The demerit of molcular dynamics was solved by using the present method.(3) This method was applied to a trobology problem, and new results were obtained.EXPERIMENTAL PROJECTFatigue process was observed with atomic force microscope.(4) Fatigue process was clarified by obcervation of atomic force microscope and crystal analysis of etch pit method. A new model of fatigue mechanism was proposed.