A conservative approach for mode I-II fatigue analysis under residual stresses: The RSIF proportionality conjecture

Residual stresses are a crucial aspect of fatigue life predictions of welded struc-tures. However, their implementation in fatigue crack growth simulations canbe tedious. In this paper, a novel approach is proposed that considers the effectsof residual stresses in a worst-case scenario by applying the maximum tangen-tial stress criterion and maximising the crack growth rate. Results demonstratethat computationally demanding analysis of residual stresses can be avoidedby assuming the residual stress intensity factors are proportional to the stressintensity factors induced by the externally applied cyclic load. This approach isreferred to as the residual stress intensity factors proportionality conjecture,whichis particularly useful for inspection planning of complex structures subject tomixed-mode crack propagation situations, where the computational recovery ofcurrent residual stress states by consideration of their temporal evolvement iscumbersome.