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Study on a non-destructive evaluation technique based on laser measurements and fast multipole method

基于激光测量和快速多极法的无损评价技术研究

基本信息

批准号：
15360238
负责人：
NISHIMURA N.
金额：
$ 6.14万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

Our group has done fundamental studies on a ultrasonic NDT which utilizes the laser velocimetry for measuring the scattered wave from unknown defects in structural members produced by a transducer induced ultrasound. Among the remaining obstacles for using this technique in real problems are the lack of practical numerical tools for solving large scale elastodynamic problems in time domain and the need to increase the frequencies used in the experiments. Since the practical NDT problems require the solution of large scale problems with Ο(10^4 spatial number of the degrees of freedom or larger, one has to use fast BIEMs rather than conventional ones in approaches which use methods of the boundary type. In view of this we have investigated the use of fast multipole method, which is considered to be practical in 3 dimensional elastodynamics in time domain. We have established a fast solver for this problem after parallelizing the code. In experiments, we have developed a laser-ultrasonic NDT system which uses higher frequencies than in our earlier studies. We have combined these techniques to investigate an NDT system which has potentials in real world problems. We have also considered the use of the YAG laser induced ultrasound in illuminating the unknown defects. As the findings of this research, we can mention the following : We have established an easy way of identifying the ultrasound produced by YAG laser. We have seen that the use of the incident wave thus identified allows the determination of surface cracks accurately. Also, in the fast method using FMM we could solve problems with millions of spatial DOFs using the parallelized FMM code with improved algorithms for the downward path.

我们的小组对超声波无损检测进行了基础研究，该技术利用激光测速仪来测量由换能器感应超声波产生的结构构件中未知缺陷的散射波。在实际问题中使用该技术的剩余障碍包括缺乏用于解决时域大规模弹性动力学问题的实用数值工具以及需要增加实验中使用的频率。由于实际的无损检测问题需要求解具有 Ο(10^4 空间自由度或更大的空间数或更大的大规模问题，因此在使用边界类型方法的方法中必须使用快速 BIEM 而不是传统的方法。鉴于此，我们研究了快速多极子方法的使用，该方法被认为在时域中的 3 维弹性动力学中实用。我们在并行化代码后为此问题建立了一种快速求解器。通过实验，我们开发了一种激光超声波无损检测系统，该系统使用比我们早期研究更高的频率。我们结合这些技术来研究具有解决现实世界问题潜力的无损检测系统。我们还考虑使用 YAG 激光诱导超声波来照亮未知缺陷。作为这项研究的结果，我们可以提及以下内容：我们已经建立了一种简单的方法来识别由 YAG 激光。我们已经看到，使用如此识别的入射波可以准确地确定表面裂纹。此外，在使用 FMM 的快速方法中，我们可以使用并行化 FMM 代码以及改进的下行路径算法来解决数百万个空间自由度的问题。