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


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.


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