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

本研究包括以下分析项目和实验项目。分析项目开发了以下的断裂微观分析新方法。(1)提出了分子动力学与连续力学的混合方法。(2)利用该方法对小尺度屈服条件下裂纹尖端前的断裂过程区进行了分析。由此得出结论，该方法可以在原子行为水平上分析断裂过程，并可以分析有限尺寸的结构。用这种方法解决了分子动力学的缺点。(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疲劳过程。(4)通过原子力显微镜观察和蚀刻坑法晶体分析对疲劳过程进行了澄清。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.