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A Numerical Comparison between Ring Indentation, Punching and Shot Peening on Fatigue Crack Retardation of Al-A356.0

Forouzanmehr, Mohsen | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 48182 (58)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Farrahi, Gholam Hossein
  7. Abstract:
  8. Most engineering components must be manufactured so they are safe to use and are ‘‘fit for purpose’’. However despite all the efforts, cracking of the engineering components is inevitable. Residual stresses play an important role in either increasing or decreasing the possibility of failure. For instance, enhancement in apparent toughness following pre-loading arises principally because of the creation of local crack tip compressive residual stresses. Introducing compressive residual stresses can also slow the fatigue crack growth. Yet, the dilemma is choosing an efficient method growth to introduce such stresses for retardation of fatigue crack growth. There are many methods available in the literature to induce compressive residual stresses. In the current research, three well known methods are compared in terms of the compressive residual stresses they can induce and how successfully they can retard the fatigue crack growth. The three methods are: ring indentation, punching and shot peening. In the punching method, the cracked specimen is punched using a solid cylinder creating compressive residual stress fields. In the ring indentation technique, residual stresses were created around the crack tip by indenting a cracked panel with rigid ring punches. Finally, in shot peening the component is bombarded with solid balls. Finite element analyses of all three techniques are carried out using commercial code ABAQUS. The created stress fields are then compared. The fatigue crack growth following application of each technique is also simulated
  9. Keywords:
  10. Finite Element Method ; Fracture Mechanics ; Plasticity ; Fatigue Crack Growth Rate ; Residual Stress ; Shot Peening

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