Investigation of Strain Measurement by Image Processing

• Main Authors: Ming-Kung Yeh, 葉銘焜
• Other Authors: Chwan-Huei Tsai
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/28043978781294816574

碩士 === 華梵大學 === 機電工程研究所 === 87 === Integrating the image processing technique and grid spot method to establish a strain measurement method is studied in this paper. The required grid spot size of the conventional spot-centroid method is very small and the marking procedure is very complicated. In this paper, an alternate image processing method is proposed to measure the geometric variation of the grid spot. The circular grid spot will change to a elliptical spot after the deformation , then the strain can be obtained from the variation of the long axis of the elliptical spot. The tensile tests are operated for the specimen which contains a hole and edge crack. The minimum strain error of the proposed strain measurement method is about 100μ in the optimal experimental environment. The measurement precision is same as the conventional spot-centroid displacement method. The experimental results of the proposed method are also compared with the numerical results of the finite element software ANSYS and the experimental results of strain gage.