Residual stress distributions and their influence on fatigue lifetimes

Residual stresses can have a significant influence on the fatigue lives of structural engineering components. For the accurate assessment of fatigue lifetimes a detailed knowledge of the residual stress profile is required. The neutron diffraction non-destructive method of measuring these stresses is described. Examples of the detrimental residual stress distributions introduced by welding and of the beneficial stresses produced by such processes as autofrettage, cold hole expansion and shot peening are presented. It is demonstrated that, provided an accurate knowledge of the residual stress profiles generated is available and allowance is made for stress redistribution and the multiaxial nature of residual stresses, reliable predictions of fatigue performance can be made.