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A Study on Quantitative Estimation Method for Fatigue Crack Propagation Behavior by Image Analysis

图像分析疲劳裂纹扩展行为定量估计方法研究

基本信息

批准号：
12650471
负责人：
TATEISHI Kazuo
金额：
$ 2.3万
依托单位：
Nagoya 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-12650471/
关键词：
fatigue fatigue crack image analysis crack propagation rate stress intensity factor microscope

项目摘要

In this study, a simple method to estimate fatigue crack propagation behavior by image analysis was proposed, and its applicability and limitations were experimentally investigated. Main results of this study is as follows, 1. On cruciform welded joints and web gusset, welded joints, experiments to measure the opening width offatigue crack by using a digital microscope, and estimate Mode I stress intensity factor for the crack were carried out. The test results showed that the stress intensity factor more than 10 Mpa/"m could be estimated with enough accuracy for engineering use.2. In order to extend the applicability of the proposed method to real bridge structural members, crack opening behavior under cyclic loaded condition was recorded by a digital microscope and a digital video camera, and the proposed estimation was carried out. On the recorded digital movie data. When the frequency is less than 5Hz, crack opening width could be measured accurately.3. The proposed method was applied to a real fatigue crack in steel bridge members. The crack showed opening/closing behavior clue to the passage of the vehicle, but. Their frequency was about Ihz, which is within the applicable condition of the proposed method.4.The method to obtain the histograms of stress intensity factor and excessive probability was proposed from the continuously measured crack opening behavior.

本文提出了一种利用图像分析估算疲劳裂纹扩展行为的简单方法，并对该方法的适用性和局限性进行了实验研究。本研究的主要结果如下：1.对十字形焊接节点和腹板节点进行了疲劳裂纹张开宽度的数字显微镜测量试验，并估算了疲劳裂纹的Ⅰ型应力强度因子。试验结果表明，该方法可以估算出大于10 MPa/“m的应力强度因子，具有足够的工程应用精度.为了将该方法推广到真实的桥梁结构构件，利用数码显微镜和数码摄像机记录了循环荷载作用下的裂纹张开行为，并进行了估算。在记录的数字电影数据上。当频率小于5 Hz时，裂纹张开宽度可以准确测量.所提出的方法被应用到一个真实的疲劳裂纹钢桥构件。裂缝显示了车辆通过的打开/闭合行为线索，但是。其频率约为1hz，在所提出方法的适用范围内。4.提出了由连续测量的裂纹张开行为获得应力强度因子和过度概率直方图的方法。