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Fatigue Life Evaluation of Ultra High Strength Notched Member using New Digital Image Correlation Method

使用新的数字图像相关方法评估超高强度缺口构件的疲劳寿命

基本信息

批准号：
18560092
负责人：
NIHSIKAWA Izuru
金额：
$ 2.27万
依托单位：
Osaka 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：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18560092/
关键词：
Digital Correlation Method Strain Displacement Notch Fatigue Strength Crack Crack Closure Notch Sensitivity

项目摘要

A new digital image correlation (DIC) method for analyzing the fracture problem of notched member was developed. At first, the application of the fast Fourier transform method is primarily employed for reduction of the analysis time. Meanwhile, a misunderstanding on the identical point searching can be avoided by using a new DIC method with the FFT treatment. Furthermore, a successful technique for the strain singular field near the crack tip was newly developed for the application of a DIC method to crack problems.On the other hand, the additional technique on measurement of multi-axial strains was also developed to measure the complex strain fields near the notch root. In this case, 3-dimensional measurement technique was needed to be applicable to monitor the transformation/strain at notch root. Multi-axial strains can be measured by using this developed system.For researching the notch sensitivity of ultra high strength steels, two types of ultra high strength steels were used in this study. Conventional fatigue tests were conducted to obtain the data on the fatigue life (fatigue strength). These data were investigated through the Kikukawa theory on fatigue strength. It was found that these strength data on the ultra high strength steel were fitted on the master curve of the Kikukawa theory.

提出了一种分析缺口构件断裂问题的数字图像相关分析方法。首先，快速傅立叶变换方法的应用主要用于减少分析时间。同时，采用一种新的离散余弦变换（DIC）方法，并结合FFT处理，避免了在搜索同一点时的误解。此外，为了将DIC方法应用于裂纹问题，还发展了一种新的裂纹尖端应变奇异场的测量技术，同时还发展了一种多轴应变测量的附加技术，用于测量缺口根部的复杂应变场。在这种情况下，需要三维测量技术来监测缺口根部的相变/应变。为了研究超高强度钢的缺口敏感性，本研究采用了两种超高强度钢作为研究对象。进行常规疲劳试验以获得疲劳寿命（疲劳强度）的数据。这些数据进行了调查，通过菊川理论的疲劳强度。结果发现，超高强度钢的这些强度数据拟合在菊川理论的主曲线上。