Fatigue crack initiation point in load carrying fillet-welded cruciform joints

摘要

Load carrying fillet-welded cruciform joints havetwo fatigue crack initiation points. They are located in the weldtoes and weld roots where high stress concentrations occur. Whichof the two serves as the initiation point depends on the weld leglength, plate thickness, and weld penetration, and the mechanismconcerned is easily understood. Some experimental results indicatethat the fatigue crack initiation point is also affected by themagnitude of the stress range. The reason for this phenomenonremains rather obscure. To establish this reason, the presentresearch study is intended to clarify the relationship between thestress range level and fatigue crack initiation point changes and toquantify the effects of the weld leg length and penetration depth onthe fatigue crack initiation point. Fatigue tests of welded jointspecimens, thermal elastic-plastic finite element method (FEM)analyses of welding residual stresses and fatigue crack propagationanalyses considering the residual stress are performed.