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Using Image Processing Technique for Measuring Strain and Stress in Complex Sheet Metals

Koohpayeh, Ali | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50020 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Asempour, Ahmad
  7. Abstract:
  8. In this project, by using the image processing method, the strain rate in the deformed sheets is measured, and then compared with experimental results. Scratches are first drawn on the surface of the sheet. After the deformation, photographs of the surface are taken, by using image processing method as well as the use of special techniques, the strain is obtained fast with accurately. By determining the strain, tension will also be achieved through Levy Mises relations. In this project, by using this method, the strain is calculated on surfaces with simple geometry, such as sphere (spherical surface of the sheet in the FLD test), as well as surfaces whose surface geometry is unknown and complicated. In this regard, a device for three-dimensional scanning of the sheet is first created by using equipment, including a camera, a laser, a stepper motor and some other tools. By using this scanner, the surface equation of sheets is obtained for desired geometry, and by obtaining the surface equation and also by applying photographs that are taken from the surface of the sheet after deformation and by using certain techniques,The dimensions of the grains are determined. By determining the dimensions of the grains, the strain is also measured. In addition, the strain has been calculated with other empirical methods such as mylar tape, caliper and micrometer, and comparison has been made between the results of these different methods. The results show that the image processing method has an acceptable accuracy and can be converted into a conventional method for calculating the strain in metal forming
  9. Keywords:
  10. Image Processing ; Stress ; Strain ; Strain Measurement ; Sheet Metal Forming

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