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Observation of crack propagation in non-metals and fracture mechanism

非金属中裂纹扩展观察及断裂机制

基本信息

批准号：
04452268
负责人：
SUZUKI Takayosi
金额：
$ 4.99万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04452268/
关键词：
crack fracture optical measurement き裂の伝播破壊機構

项目摘要

The propagation velocity of crack can be measured with high resolution with a optical system because when a light beam incidents obliquely on a very flat crack plane in a transparent solid, it can be totally reflected at the crack plane. The objective of this study is to understand the fracture mechanism in solid. The optical method with high-speed response has already been established, then by using the grant we planed to observe the shape of the crack tip together, too. With this apparatus the crack propagation mainly in NaCl single crystals was measured and the change of the shape of the crack tip was observed with 0.1 musec resolution.In the first year, we divided the parallel laser beam into several long and narrow ones and constructed the optical system by using a multi-channel wave memory to measure the change of the intensity of every light beam at the same time. In the last year, the number of the channels was improved from 4 to 8, although it was very difficult to eliminate the interference among the channels because the photo sensors with high frequency and the amplitudes are set up in narrow space each other. By the observation of crack extension in NaCl single crystals, we made the following clear. Crack extension is not uniformly both spatially and temporally. That is ; the initiation of crack propagation occurs locally and proceeds through its expansion. In some cases, one part of the crack may begin to propagate very late.The crack velocity often reaches the maximum value (about 1000m/sec) immediately after its initiation of propagation and crack can also propagate, on the other hand, at the lower speed at the beginning and at the upper later. For the experiment of the observation of the crack propagation in semi-conductor that is one of the objective of this plan, the measurements could not be run with adequate resolution because of lack of uniformity of the laser beam.

当光束斜入射到透明固体中非常平坦的裂纹面上时，它会在裂纹面处发生全反射，因此可以用光学系统高分辨率地测量裂纹的扩展速度。本研究的目的是了解固体中的断裂机制。高速响应的光学方法已经建立起来，然后我们也计划利用这个赠款一起观察裂纹尖端的形状。用该装置测量了NaCl单晶中的裂纹扩展，观察到了裂纹尖端形状的变化，其分辨率为0.1 μ sec。第一年，我们将平行激光束分成多束狭长光束，用多通道波存储器构成光学系统，同时测量每束光束强度的变化。在过去的一年中，通道的数量从4个增加到8个，尽管由于具有高频率和振幅的光传感器彼此设置在狭窄的空间中，因此很难消除通道之间的干扰。通过对NaCl单晶中裂纹扩展的观察，我们明确了以下几点。裂纹扩展在空间和时间上都不是均匀的。也就是说，裂纹扩展的起始发生在局部，并通过其扩展进行。在某些情况下，裂纹的一部分开始扩展很晚，裂纹速度往往在开始扩展后立即达到最大值（约1000 m/sec），裂纹也可以在开始时以较低速度扩展，以后以较高速度扩展。对于作为本计划目标之一的半导体中裂纹扩展的观察实验，由于激光束缺乏均匀性，测量无法以足够的分辨率进行。