Loading...

Effects of Laser Peening with Different Coverage Areas on Residual Stress and Fatigue Crack Growth

Bikdeloo, Rasool | 2018

1482 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50849 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Farrahi, Gholamhossein; Mehmanparast, Ali
  7. Abstract:
  8. Failure due to fatigue loading is one of the main reasons for the wear out of parts in the industry. Prevention of failure and improving the fatigue life of materials have been studied by many researchers. Desirable compressive residual stress have important effect on improving the lifetime of materials. Laser peenning leads to increase fatigue life of metals by creating compressive residual stress at the surface of the pieces.This study investigates the effect of different laser coverage areas on residual stresses using finite element method and also investigates the fatigue crack growth experimentally.Simulation results show that increasing the laser peening rows impart the residual stress in bigger zone, but new rows reduce the residual stress in the previous row due to heterogeneity of the stress around the laser. Increasing overlap between laser pulses leads to an increase in the amount and depth of the residual stress. Multiple peening also have the same results, but it has more effect on increasing the amount and depth of the residual stress than increasing overlap.The effect of multiple peening on the fatigue crack growth investigated experimentally. It was observed that the multiple peening decreases the fatigue crack growth rate. The fatigue crack growth life in the sample without laser peening was 84380 cycles while in the sample with one laser peening and the one with two laser peening operation increases to 104130 and 170500 cycles respectively indicating a significant increase in fatigue life
  9. Keywords:
  10. Fatigue ; Residual Stress ; Fatigue Crack Growth Rate ; Peening Laser

 Digital Object List

 Bookmark

...see more