Numerical and experimental investigations on the fatigue life evaluation of butt-welded joints

In many applications, welded components are subjected to complicated states of stress and strain due to complex loading and welding residual stresses. Fatigue under these conditions, termed multiaxial fatigue, is an important design consideration for reliable operation of welded components. This investigation develops an effective procedure to predict fatigue life in the weldments by combining the thermo-elasto-plastic theory, multiaxial fatigue theory, and finite element methods. The proposed procedure, which followed the conventional strain-based method (maximum principal strain and von Mises effective strain) to predict the fatigue life of the butt-welded joints, was fairly sensitive to welding residual stress. Furthermore, fatigue tests of steel butt welds having tensile residual stresses were conducted to verify the proposed procedure. Comparative results demonstrate that fatigue life estimates made using the novel procedure closely approximate experimental results.