Welding residual stress impact on fatigue life of a welded structure

A welded component has been fatigue tested and then analyzed using both the nominal stress approach and the fracture mechanics approach. The nominal stress approach predicted the wrong failure location as well as a very short fatigue life. A welding simulation was then performed to understand the residual stresses generated in the structure by welding. Results showed a highly compressive stress state at the low life location predicted by the nominal stress approach. A fracture mechanics-based assessment of fatigue was then performed, incorporating welding residual stresses. The results showed excellent agreement with the fatigue test results, emphasizing the important role played by residual stresses in determining the failure location.