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Effect of Grinding and Shot Peening on Fatigue Life of Welded Joints

Hassani Gangaraj, Mostafa | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40514 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Farrahi, Gholamhossein
  7. Abstract:
  8. Metallurgical initial defects, stress concentration due to change in geometry and induced tensile residual stress during welding create an extraordinary high possibility of fatigue cracks nucleation and propagation in the weld toe region. Despite this, the ever increasing use of welding in offshore, aerospace and automotive industries, as the most applied mechanical joint, has occasioned a very extensive attempt to achieve an in-depth understanding of failure mechanisms and fatigue life improvement techniques of welded joints. Generally, these techniques could be classified into two broad categories. The first consists of methods that modify the geometry and the other is related to the modification of the residual stress distribution. Because of their simplicity and low cost, grinding amongst the first class and shot peening from the second class are almost always taken into consideration by different industries. Finite element simulation of welding, grinding and shot peening were presented in this work. Using linear elastic fracture mechanics, the effects of grinding, shot peening and combination of them on fatigue crack growth life of welded joints were examined. The result demonstrated that the toe grinding generally improve the fatigue life to an average value of 60%, depending on amount of loading and crack size. However, the minimum improvement achieved by combination of grinding and shot peening is 650% in terms of cycles to fracture. Combination of grinding and shot peening also introduces a threshold level of loading below that crack does not propagate
  9. Keywords:
  10. Welded Joint ; Shot Peening ; Grinding ; Fatigue Life ; Crack Growth ; Fatigue Crack Growth Rate

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