Application of a two-surface plasticity model for thermal ratcheting and failure life estimation in structural model tests

In the structural design of elevated temperature components of liquid metal fast breeder reactor plants, detailed inelastic analysis needs to be applied when design code criteria for preventing excessive deformation or creep-fatigue failure cannot be satisfied by elastic design routes. Because the results of inelastic analysis are fully dependent on the material deformation models used, development of a reliable inelastic constitutive model is essential for application of detailed inelastic analysis to design assessment. In this study, one of the recent plastic constitutive models developed by the author, which belongs to a category of two-surface models, was applied to inelastic analysis of two types of type 304 stainless steel structural models subjected to repeated thermal cycles. The conventional life estimation method employed in the present design rules was used for the prediction of failure life due to thermal fatigue or creep-fatigue interaction. Reasonable agreement was obtained between the test results and the predictions in regard to thermal ratcheting behaviour and crack initiation life. ((orig.))