DOI QR코드

DOI QR Code

Research for Fatigue Life Extension Techniques in Weldments via Pneumatic Hammer Peening

공압식 헤머피닝을 이용한 용접부 피로수명 연장기술 연구

  • 한정우 (한국기계연구원 시스템엔지니어링연구본부) ;
  • 한승호 (동아대학교 기계공학과)
  • Published : 2009.08.01

Abstract

Fatigue failures are often occurred at welded joints where stress concentrations are relatively high due to the joint geometry. Although employing good detail design practices by upgrading the welded detail class enables to improve the fatigue performance, in many cases, the modification of the detail may not be practicable. As an alternative, the fatigue life extension techniques that reduce the severity of the stress concentration at the weld toe region, remove imperfections and introduce local compressive welding residual stress, have been applied. These techniques are also used as definite measures to extend the fatigue life of critical welds that have failed prematurely and have been repaired. In this study, a hammer peening procedure for using commercial pneumatic chipping hammer was developed, and the effectiveness is quantitatively evaluated. The pneumatic hammer peening makes it possible to give the weld not only a favorable shape reducing the local stress concentration, but also a beneficial compressive residual stress into material surface. In the fatigue life calculation of non-load carrying cruciform specimen treated by the pneumatic hammer peening, the life was lengthened about ten times at a stress range of 240MPa, and fatigue limit increased over 65% for the as-welded specimen.

Keywords

Fatigue Life Extension;Mechanical Surface Post Treatment;Pneumatic Hammer Peening

References

  1. Haagensen, P. J., 2003, 'Fatigue Improvement Techniques - Advantages and Limitations,' Welding in the World, Vol. 47, pp. 43~63
  2. Haagensen, P. J. and Maddox, S. J., 2001, 'IIW Recommendations on Post Weld Improvement of Steel and Aluminium Structures,' IIW Commission XIII, XIII-1815-00
  3. Kang, S. W., Kim, M. H, Choi, J. Y., Kim W. S. and Paik Y. M., 2006, 'A Study on the Fatigue Strength Improvement using Weld Toe Burr Grinding,' Journal of KWS, Vol. 24, No. 2, pp. 150~155
  4. Lee, S. H., 1980, 'Shot Peening Process,' Journal of KSME, Vol. 20, pp. 194~200
  5. Lee, J. K. and Kim, J. K., 1997, 'Influence of Residual Stress due to Shot Peening on Fatigue Strength and Life,' Trans. of the KSME, Vol. 21, No. 9, pp. 1498~1506
  6. Roy, S., Fisher, J. W. and Ben, T. Y., 2003, 'Fatigue Resistance of Weld Details enhanced by Ultrasonic Impact Treatment(UIT),' International Journal of Fatigue, Vol. 25, pp. 1239~1247 https://doi.org/10.1016/S0142-1123(03)00151-8
  7. Han, S. H. and Han, J. W., 2005, 'Fatigue Life Estimation of Fillet Welded Joints Considering Statistical Characteristics of Weld Toe's Shape and Multiple Collinear Surface Cracks,' Journal of KWS, Vol. 23, No. 3, pp. 158~167
  8. American Society for Testing Materials, 'Determining Residual Stresses by the Hole-Drilling Strain Gage Method' ASTM E 837
  9. Reemsnyder, H., 1981, 'Evaluating the Effect of Residual Stresses on Notched Fatigue Resistance,' Materials, Experimentation and Design in Fatigue, pp. 273~295
  10. Smith, K., Watson, P. and Topper T., 1970, 'A Stress-Strain Function for the Fatigue Damage,' J. Mater., Vol. 5-4, pp.767~778
  11. Kirkhope, K. J. et al., 1999, 'Weld Detail Fatigue Life Improvement Techniques,' Marine Structures, Vol. 12, pp. 447~474 https://doi.org/10.1016/S0951-8339(99)00013-1
  12. Han, J. W. and Han, S. H., 2005, 'Fatigue Life Estimation of Welded Joints Considering Statistical Characteristics of Multiple Surface Cracks,"\' Trans. of the KSME, Vol. 29, No. 11, pp. 1472~1479 https://doi.org/10.3795/KSME-A.2005.29.11.1472