Development of a model for Hydro-Mechanical Deep Drawing Process to Analyze the Effects of Assumptions and Parameters

Taghipour, Ehsan | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40381 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Assempour, Ahmad
  7. Abstract:
  8. It is the goal of this thesis to develop an analytical model for the hydro-mechanical deep drawing (HDD) process of an axisymmetric sheet metal with the fixed gap method to evaluate the effects of some assumptions such as: proportional loading, plane stress, and constant thickness conditions. The effect of parameters on the HDD process is also studied. The main model is developed with considering the normal stress and part thickness change, non-proportional loading, bending and unbending effects at the top of the cup wall. The interrelationships between geometrical and mechanical variables are obtained in the finite difference form based on the incremental strain theory, thereby being solved by Broyden algorithm. Moreover, Published FEM results and experimental data are to be used for evaluation of the results obtained in the present work. The results obtained from the models under proportional loading condition, plane stress, or constant thickness condition show more differences with the experimental findings in thickness variation, and strain distribution than the results of the main model. Besides, at the bottom of the cup wall of the St12-made part, non-proportional loading condition leads to 6% increase in thickness, 23% decrease in radial strain, and 24% decrease in circumferential strain. Moreover, thickness increases by 3% and radial strain decreases by 17% under plane stress assumption in comparison with the 3-D stress state. Constant thickness assumption results in considerable miscalculation of the radial and circumferential strains, especially at the bottom of the cup wall. Also, there is an 11% increase in thickness at the bottom of the cup wall when assuming thickness to be constant rather than variable. Thus, the non-proportional loading, normal stress, and thickness change should be considered in the design of HDD process for higher accuracy.
  9. Keywords:
  10. Finite Difference Method ; Normal Stress ; Variable Thickness ; Hydroforming ; Hydromechanical Deep Drawing ; Nonproportional Loading

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