압축잔류응력을 고려한 면외거셋 용접이음부의 피로수명 예측

Abstract

Blast treatment is an important process in the manufacturing of steel structures in Korea. It's purpose is to remove the impurities on the surface of steel material and to enhance the adhesiveness of coating. But, the effect of the blast treatment on fatigue behavior of welded joints has not been considered. In this study, fatigue tests were carried out on out-of-plane gusset welded joints, the fatigue strength of specimen has increased by blast treatment and it was mainly because the residual compressive stress was introduced. In the fatigue test results showed that fatigue life of welded joints can be improved by the blast cleaning treatment. Over 167% increase in fatigue limit could be realized by using blast cleaning treatment but in the high stress range, there is no significant different in fatigue limit oof the as-welded specimen. So, it is necessary to evaluate the residual compressive stress quantitatively. The compressive residual stress induced on surface of blast-treated specimen has been supposed to be the major factor improving the beneficial fatigue strength of welded joints. In this paper provides the analysis of fatigue life considering effect of compressive residual stress on fatigue behaviour. The prediction results present that fatigue life of blast-treated specimen is higher than that of as-welded specimen and the ratio of crack depth and crack length has little effect on the fatigue strength of out-of-plane gusset welded joints.