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Implementation of Shear Stress in M-K Model for Determination of the Limit Strains

Ghazanfari, Ahmad | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48333 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Asempour, Ahmad; Hashemi, Ramin
  7. Abstract:
  8. One of the most useful methods in metal forming is Sheet Metal Forming. Use of Forming limit diagrams (FLD) in designing is a conventional method. Therefore many experimental and theoretical efforts have been carried out in order to investigate the FLDs. Many ways to obtain this FLDs and their effective parameters have been studied. But the stress state at these studies is planar which lead to an untrue model for several metal forming process such as incremental sheet forming. With this technique, the forming limit curve (FLC) appears in a different pattern, revealing an enhanced formability, compared to conventional forming techniques. Therefore, in this study, the effect of through thickness shear stress has been examined on the prediction of the forming limit diagrams (FLDs). Determination of the FLD is based on the Marciniak-Kuczynski (M–K) model with some modifications on the stress states for consideration of the through thickness shear stress effects. For solving the equations, the Newton-Rafson method has been used. The Nakazima test has been simulated to investigate the stress state which occurs in sheet blank during the test. Results showed that the formability of sheet metal could be better as the through thickness stress increased. Also, implementation of investigated TTS in the present model, case FLD to has better agreement with the experimental result
  9. Keywords:
  10. Forming Limit Diagram (FLD) ; Marciniak-Kuczynski Model ; Shear Stress ; Implementation ; Through Thickness Shear Stress ; Nakazima Test ; Incremental Sheet Forming

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