411-418In this investigation, low cycle fatigue tests were carried
out and mechanical characteristics of three materials (steel of grades 15X2MFA
and 45 and aluminium alloy D16T1), representing all possible variations of
cyclic properties (fatigue, quasi-static and intermediate mode of fracture)
were determined experimentally. Based on the data obtained, design curves of
equal fracture probability for steels 15X2MFA and 45 and aluminium alloy D16T1
at low cycle strain-controlled loading were generated and the design curves
were compared with experimental data. Analysis of calculated and experimental
low cycle fatigue curves constructed according to the fracture probability
parameter, revealed that the use of analytical relationships for lifetime
assessment of structures may lead to an error and decreasing safety margin. It
is recommended to use experimental 50% fracture probabilistic curves in
lifetime assessment of power equipment structures