A Monitoring System of Inner Surface Cracks in Plant Pipes by Electric Potential CT Method

电厂管道内表面裂纹电位CT法监测系统

基本信息

批准号：
63850024
负责人：
OHJI Kiyotsugu
金额：
$ 6.66万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-63850024/
关键词：
Non-Destructive Inspection Electric Potential Method Surface Crack Computed Tomography Method Inverse Analysis Fracture Mechanics Boundary Element Method Pipe 裏面き裂

项目摘要

The present investigators proposed the electric potential CT method for estimating locations, shapes and sizes of two- and three-dimensional cracks in conductive bodies from electric potential distributions based on boundary element inversion analysis schemes. In the present study the method was applied for monitoring inner surface cracks in plant pipes. The main results obtained are summarized as follows.1. A simplified inverse analysis scheme was proposed to identify surface cracks on back-faces by computer processing of the electric potential distribution using a workstation. In this scheme hierarchical method was introduced, in which two-dimensional scanning analyses were combined with three-dimensional inverse analyses. To achieve a high speed computation on the workstation, analytical expressions of electric potential distribution reported by Johnson was used in the two-dimensional scanning analyses, and data base of electric potential distribution on three-dimensional cracked bodies was utilized in the three-dimensional inverse analyses. 2. To automatically determine the crack locations and shapes from electric potential distributions, optimization schemes were incorporated in the crack determination based on the three-dimensional least residual method. 3. Numerical simulations were conducted for determining crack locations and shapes from electric potential distributions. It was shown that the proposed schemes worked well for the determination of cracks. 4. The data base of electric potential for cracked plates can be used for identifying cracks in plates with curvature or pipes, if cracked area was taken as a major variable of the electric potential distribution. 5. The electric potential distributions were measured on surfaces of cracked plates and pipes. The location and shape of cracks were successfully identified from the electric potential distributions by the proposed schemes. 6. These results showed the usefulness of the proposed schemes.

本研究人员提出了电势CT方法，用于估算基于边界元素反转分析方案的电势分布的导电体中二维和三维裂纹的位置，形状和大小。在本研究中，该方法用于监测植物管道中的内表面裂纹。获得的主要结果总结如下1。提出了一种简化的逆分析方案，以通过使用工作站对电势分布进行计算机处理来识别后面的表面裂纹。在此方案中，引入了层次结构方法，其中将二维扫描分析与三维逆分析相结合。为了实现工作站上的高速计算，约翰逊报告的电势分布的分析表达式用于二维扫描分析，并在三维逆分析中使用了三维破解物体的电势分布的数据库。 2。为了自动确定电势分布的裂纹位置和形状，根据三维最小残留方法，将优化方案纳入了裂纹测定中。 3进行了数值模拟，以确定电势分布的裂纹位置和形状。结果表明，所提出的方案在确定裂纹方面效果很好。 4。如果将破裂的面积作为电势分布的主要变量，则可以使用破裂板的电势数据库来识别板块或管道的裂纹。 5。在破裂的板和管道的表面上测量电势分布。裂纹的位置和形状由拟议方案成功地从电势分布中鉴定出来。 6。这些结果表明了所提出的方案的有用性。