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The Crack Detection Using Dynamic X-ray Stress Measurement during Fatigue Test

疲劳试验中动态X射线应力测量的裂纹检测

基本信息

批准号：
11650103
负责人：
OHYA Shin-ichi
金额：
$ 1.6万
依托单位：
Musashi Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650103/
关键词：
X-ray stress measurement Single exposure technique Detection of fatigue crack Actual stress distribution Surface crack Internal crack Residual stress distribution 疲労強度片持ち回転曲げ疲労試験ショットピーニング処理圧縮残留応力

项目摘要

The purpose of this investigation is to detect both a surface and an internal fatigue cracks from actual stress distribution in the surface of specimen by using X-ray diffraction technique during fatigue test.In 1999, an apparatus to measure actual stress distribution along circumference of specimen was fabricated by use of a cantilever type rotary bending fatigue machine and a stress analyzer based on single exposure technique with two position sensitive proportional counters. The method to collect separately the diffraction profile at each position along circumference of specimen was developed. Actual stress distributions at the maximum tensile applied stress were measured using an annealed carbon steel S45C specimen during fatigue test.As a result in 1999, the shape of actual stress distribution was keeping stable with increasing number of stress cycles until surface crack initiation. After surface crack initiation, the actual stress at the position of surface crack initiation was d … More ecreased suddenly near 0 MPa, and the distribution was shaped "V" type. The "V" type distribution was appeared when crack length reached greater in size than a width of irradiation area.In 2000, the actual stress distributions on shot-peened S45C specimen were measured during fatigue tests to clarify the behavior of compressive surface residual stress through fatigue process. As a result in 2000, the actual stress at every position on specimen circumference was roughly the same value as the algebraic sum of the compressive residual stress and the maximum tensile applied stress until surface crack initiation. However, after a macro surface crack was appeared, the actual stress distribution was showed V-shape at crack position. The actual stress at the bottom of V-shaped distribution was the same value as the compressive residual stress.In 2001, the actual stress distributions on shot-peened ductile cast iron FCD600 specimens were measured during fatigue tests to clarify a possibility of the internal fatigue crack detection using change in surface actual stresses distribution. As a result in 2001, it was confirmed that the peak position in the actual stress distribution agreed with the internal crack position.The method proposed in this investigation is useful for detecting a position of both a surface and an internal cracks. On the other hand, the residual stress distributions showed no significant change even where the internal crack and the surface cracks existed, whereby the crack could not be detected by change in the residual stress distribution. Less

本研究的目的是利用x射线衍射技术从疲劳试验中试样表面的实际应力分布中检测出表面和内部的疲劳裂纹。1999年，利用悬臂式旋转弯曲疲劳试验机和基于单曝光技术的应力分析仪，采用两个位置敏感比例计数器，制作了一套沿试件周长实际应力分布测量装置。提出了沿试样圆周分别采集各位置衍射剖面的方法。在疲劳试验中，使用退火碳钢S45C试样测量了最大拉伸施加应力时的实际应力分布。结果表明，在1999年，随着应力循环次数的增加，实际应力分布形状保持稳定，直至表面裂纹萌生。表面裂纹起裂后，表面裂纹起裂位置的实际应力在0 MPa附近突然增大，并呈“V”型分布。当裂纹长度大于辐照区宽度时，裂纹呈“V”型分布。2000年，在疲劳试验中测量了喷丸S45C试样的实际应力分布，以阐明疲劳过程中表面压缩残余应力的行为。因此，在2000年，试样周长各位置的实际应力大致等于表面裂纹萌生前的残余压应力和最大拉应力的代数和。而宏观表面裂纹出现后，裂纹位置的实际应力分布呈v型。v形分布底部的实际应力值与压残余应力值相同。2001年，在疲劳试验中测量了喷丸球墨铸铁FCD600试样的实际应力分布，阐明了利用表面实际应力分布变化检测内部疲劳裂纹的可能性。结果在2001年，确认了实际应力分布中的峰值位置与内部裂纹位置一致。本研究中提出的方法对于检测表面和内部裂纹的位置都是有用的。另一方面，即使存在内部裂纹和表面裂纹，残余应力分布也没有明显变化，通过残余应力分布的变化无法检测到裂纹。少