On design cycles counting in regulatory fatigue strength estimation

A problem of design-based cycles counting for fatigue assessments of structures without initial cracks is considered in terms of requirements of strength analysis regulations for nuclear engineering components according to crack nucleation criterion. It is shown that a higher conservatism of these requirements for design stage analysis does not permit to apply the widely distributed rain-flow method. An alternative algorithm of cycles counting is presented. It satisfies the regulations requirements and is easy to realize in design practice.