Two current approaches to prediction of life to crack initiation are reviewed, the first based on modification of fatigue types of analyses, the second on use of cumulative fatigue and creep damage models. Methods of allowing for stress and strain concentrations are examined, and attention directed to the possibility of environment significantly affecting results. The fracture mechanics approach to estimating rates of crack propagation is discussed.

For computer analyses of highly critical sections of components, formulation of constitutive equations on a continuum-metallurgical basis is considered, some possible directions for future work are indicated. An example of prediction of failure through growth of voids in creep is given.

Finally, present design practice is outlined, and the importance of accurate knowledge of service conditions emphasized.