Mechanisms of the Transition in Static Fatigue of Pristine Silica Optical Fibers

原始石英光纤静态疲劳转变机制

基本信息

批准号：
12650069
负责人：
MURAOKA Mikio
金额：
$ 1.79万
依托单位：
Akita University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650069/
关键词：
Silica optical fibers Transition Aging Self-affined surface Stress concentration Stochastic differential equation Atomic force microscope Fluctuation of dissolution rate 複雑系モデル

项目摘要

The study aims to clarify a mechanism of"transitions" in static fatigue of pristine silica optical fibers under a stress and to present a method of predicting the phenomenon. The transition is a turning point where a trend in strength degradation of fibers changes abruptly. The research results are summarized as follows:1. Preliminarily we investigated an aging behavior of fibers in liquid water at 90 ℃, where the aging is a strength degradation under no stress and is recognized as a phenomena very close to the transitions. Atomic force microscopy (AFM) for aged surfaces of fibers showed that the surface roughness grows in proportion to a power of aging time but the profile keeps a self-affined fractal with a Hurst' index of 0.85. We also simulated aging of fiber based on a stochastic differential equation (SDE) taking account of a fluctuation of dissolution rate of silica. The simulations were able to explain the experimental results qualitatively. This insists that aging is caused by … More a fluctuation of dissolution rate. Stress analysis for aged surface profiles also showed that a stress concentration factor is a key parameter to predict aging of fibers.2. We simulated growth of surfaces roughness for fibers under a constant stress by using SDE It is found form the simulations that a main crack develops quickly and the crack growth controls lifetime of fibers at high stress conditions before transitions, but roughness developments dominates at low stress conditions after transitions.3. Observations of fiber surface profile are useful to predict a remained lifetime of fibers under a service use. To compensate a limited resolutions of AFM, we focused on an apparent contact stiffness between to AFM tip and sample surface. The stiffness must be affected local small roughness inside the contact area. Previously, we developed a special AFM cantilever with its mass concentrated as a way of enhancing the sensitivity in detection of a contact stiffness. In the present study, we produced a method of evaluating an elastic modulus of sample with a lateral resolution of about lOnm quantitatively. This method would be useful to detect a surface roughness of atomic levels. Less

该研究旨在阐明“在压力下原始光纤的静态疲劳中的机制，并提出一种ingonomenon的方法。过渡是一个转折点，其中时尚的纤维降解突然变化。研究结果总结了以下内容。：1。我们研究了在90°C的液体水中纤维在90°C下的衰老行为。衰老时间，但在0.85的HIRST上，我们还基于随机微分方程（SDE）模拟纤维的老化。由于……对年龄表面的应力分析的更多波动也表明，应力概念因子是使用SDE预测的关键参数。在过渡之前控制纤维的寿命，但是在过渡后的低应力条件下的粗糙度发展。3。与AFM尖端和样品表面之间的联系，刚度必须在触觉内部局部。，我们产生的样品弹性模块是大约的横向分辨率。