Strain and Stress Measurement by Image Processing Technique<br/>

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Strain and Stress Measurement by Image Processing Technique

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 46129 (08)
University: Sharif University of Technology
Department: Mechanical Engineering
Advisor(s): Assempour, Ahmad
Abstract:
This study presents an image processing technique for automatic strain and stress measurement in sheet metals. In order to measure the strain automatically, the sheet blank is electrochemically etched to create circular and rectangular grids. After press forming of the sheet, circular grids are deformed into elliptical grids and rectangular grids are deformed into quadrilateral grids. Different photos are captured for using in image processing technique. These photos are taken in different positions. Finally strain can be measured by processing these photos and the stress is obtained by using Levy-Mises flow rule. In this study, three methods of image processing technique are simultaneously applied. Various errors in image processing technique are detected in single and multi grid measurements. The strain measurement error is reduced by using this technique (three different methods). A digital camera, a simple computer are used for automatic strain measurement in tensile test. Other results are manually obtained by reading the circle and ellipse major and minor axis length through a microscope, myler tape and caliper. There is a good agreement with the results of automatic measurement
Keywords:
Strain ; Stress ; Image Processing ; Plate Forming

No TOC