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Investigate the Formation of Metal Sheets by Damage Mechanics

Amirshekari, Yaser | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50685 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Asempoor, Ahmad
  7. Abstract:
  8. One of the oldest and most used methods in shaping metals is the formation of metal sheets. In designing the process of printing, it's important to know how much the strain on the sheet prior to slipping is. In order to predict the permissible strains in the two-axis stretch of the sheet, they introduced an empirical diagram called the shape-forming diagram. There are various methods for analyzing the formation of metallic sheets, which can be referred to by M-K method, GTN method, continuous damage mechanics method (CDM). In this research, we have tried to obtain the shape of a metal sheet in various strain paths by studying the method of CDM and modeling the mechanical behavior of the material along with damage with the help of the limited element software ABAQUS. For this, it is necessary to obtain the mechanical properties of the sheet (AL 2024 TO) by means of a stretch test, and then, on the tested specimens, a microhardness test is performed to obtain the amount of damage with the help of variations in the hardness at different points of the sample. Then, by modeling the mechanical behavior of the material and determining the properties of matter in the form of the Abacus program, the process of shaping the sheet in Abakus is simulated and the shaping limit is determined. Also, for comparing and validating the results of the CDM method, the GTN method and the experimental method of Nakakism are used. In the GTN method, it is necessary to determine the coefficients for the sheet type. To do this, an attempt has been made to obtain the optimal coefficients by modeling the tensile test performed in the Abacus software and comparing the results of the software and the experiment. Then, the modeling model it is processed in the CDM, and the extraction limit is extracted. Finally, the Nazi experimental experiment was conducted to extract the formation limit to prove the accuracy of the results
  9. Keywords:
  10. Forming Limit Diagram (FLD) ; Gurson-Tvergaarol-Needleman (GTN)Model ; Continuum Damage Mechanics ; Sheet Metal Forming ; Metal Sheets

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