Development of Genetic Algorithms based System for High-Precision Reconstructions of Three-Dimensional Topographies using Stereo Fractographs

基于遗传算法的立体断口高精度三维地形重建系统的开发

基本信息

批准号：
10555029
负责人：
MINOSHIMA Kohji
金额：
$ 8.45万
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：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

A software is developed which enables reconstruction of the three-dimensional (3-D) shape of fracture surfaces without human assistance. It is based upon computer image processing and pattern recognition techniques by using a stereo-pair of scanning electron micrographs. The processing consists of two subprocesses : searching the matching points between two images and computation of heights using the relative shift of the matching points. By using the previously developed system, some mismatches were inevitable in the search process, in particular, for low-contrast SEM images such as striations, intergranular facets, and so on. In order to improve the accuracy of the search, a Genetic Algorithm (GA) was implemented into the developed system. By using the GA method, the 3-D shapes of a wide variety of fracture surfaces including cleavage failures, intergranular cracking, dimples and fatigue striations, were successfully reconstructed with sufficient accuracy. The searching processes by the GA method and the previously developed two-step algorithm of coarse and close searching were compared. These proved that the GA method has the advantage of accuracy in the searching process and of short-run-time. A detailed 3-D shape, or more than a 120×120 reconstructed point-sized shape, was thus obtained with sufficient accuracy and with a relatively short-run-time. The developed system was also applied to the fatigued fracture surfaces of a stainless steel (SUS316NG) and a low-alloy steel (SGV420), and the relationship between quantitative topographic measures and stress intensity factors and/or crack growth rates was discussed.

开发了一个软件，该软件可以重建裂缝表面的三维（3-D）形状，而无需人为援助。它基于计算机图像处理和模式识别技术，通过使用扫描电子显微照片的立体评级。该处理由两个子过程组成：使用匹配点的相对偏移搜索两个图像之间的匹配点和高度计算。通过使用先前开发的系统，搜索过程中不可避免的一些不匹配，尤其是对于诸如条纹，晶间刻面等的低对比度SEM图像等。为了提高搜索的准确性，将遗传算法（GA）实施到开发的系统中。通过使用GA方法，以足够的精度成功地重建了多种断裂表面的3-D形状。比较了GA方法的搜索过程以及先前开发的粗糙和近距离搜索的两步算法。这些证明，GA方法在搜索过程和短期时间内具有准确性的优势。因此，以足够的精度并且相对较短的时间获得了详细的3-D形状，或超过120×120重建点大小的形状。开发的系统还应用于不锈钢（SUS316NG）和低合金钢（SGV420）的疲劳裂缝表面，并讨论了定量地形测量和/或裂纹生长速率之间的关系之间的关系。