Responses of Angle-Beam Ultrasonic Shear Waves to Closed Cracks and Highly Sensitive Quantitative Nondestructive Evaluation of Crack Sizes Together With Closure Stresses

角束超声波剪切波对闭合裂纹的响应以及裂纹尺寸和闭合应力的高灵敏度定量无损评估

基本信息

批准号：
12450041
负责人：
SAKA Masumi
金额：
$ 10.11万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
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

项目摘要

1. Clarification of angle-beam shear wave responses to closed cracks and its mechanismSpecimens containing two-dimensional (2D) fatigue cracks with different crack depths and closing stresses were prepared, and the cracks situated vertically on the specimen back-wall were inspected. The beam angle for achieving considerable sensitivity in shear wave response for a wide range of cracks was estimated as 50°.2. Construction of theoretical model of angle-beam shear wave response to closed crackBy taking care of the shape of the response curve that contains the simultaneous information of crack depth and closing stress, the model of angle-beam shear wave response has been proposed.3. Evaluation of crack size and closing stress by inverse analysis(1) Verification for small two-dimensional closed cracksA relation between the amplitude of the crack echo and the crack depth for open cracks was determined. Then, another relation between the reflection coefficient, which is defined by the ratio of echo-height of closed, crack to that of open crack, and crack closure stress was obtained. Finally, by using the model of closed crack response constructed in the previous section 2, which contains these relations, the values of crack closure stress and crack depth of an unknown 2D crack have been determined by solving an inverse problem.(2) Extension to shallow three-dimensional closed cracksThe methodology of evaluating 2D closed crack was extended to shallow 3D closed crack. Since a small segment of length of a 3D shallow crack can be approximated as a segment of 2D crack, the inverse analysis for the response measured at the center of each segment was individually performed.(3) Verification for shallow three-dimensional closed cracksCrack closure stress and the crack tip contour of a 3D closed crack were determined by the technique developed in the above section (2).

1。对闭合裂纹的角色剪切波响应的澄清及其机制，含有二维（2D）疲劳裂纹具有不同的裂纹深度和闭合应力，并检查了样品背壁的裂纹。据估计，用于在剪切波响应中实现考虑较大裂纹的敏感性的光束角估计为50°.2。构造对封闭裂纹的角束剪切波反应的理论模型，以照顾包含裂纹深度和闭合应力的简单信息的响应曲线的形状，已经提出了角束剪切波响应的模型3。通过反分析评估裂纹大小和闭合应力（1）确定裂纹回波放大器与开放裂纹的裂纹深度之间的小二维闭合裂纹关系的验证。然后，反射系数之间的另一种关系是由封闭的回声高度，裂纹与开放裂纹的裂纹和裂纹闭合应力所定义的。最后，通过使用上一个第2节中构建的封闭裂纹响应的模型，其中包含这些关系，通过解决一个反问题来确定裂纹闭合应力和未知2D裂纹的裂纹深度的值。（2）扩展到浅的三维闭合裂纹，将评估2D裂纹的方法扩展到浅3D闭合裂纹。由于可以单独执行3D浅裂纹长度的一小段作为2D裂纹的片段，因此分别执行在每个段中心测量的响应的反向分析。（3）验证验证三维闭合裂纹闭合应力的浅裂纹闭合应力，并通过上述技术在上述技术中确定了3D闭合裂纹的裂纹轮廓。

项目成果

期刊论文数量（47）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

M.A.Salam Akanda (M.Saka): "Influence of Crack Length on the Ultrasonic Evaluation of Depth of Small Surface Cracks"Proc.Asian Pacific Conf.on Fracture and Strength '01 and Int.Conf.Advanced Technology in Experimental Mechanics '01. 1. 253-257 (2001)

M.A.Salam Akanda (M.Saka)：“裂纹长度对小表面裂纹深度超声评估的影响”Proc.Asian Pacific Conf.on Fracture and Strength 01 和 Int.Conf.Advanced Technology in Experimental Mechanics 01。