Fatigue Modelling of a Notched Geometry Under Variable Amplitude Loading Supported on Elastoplastic FEM Analyses

Abstract

Despite intensive research has been carried out to understand the fatigue behavior of steel notched geometries, under variable amplitude loading, no definite and general robust models have been derived so far. Therefore, any effort to increment the knowledge in the topic is welcome. Within this premise, it is proposed an assessment of existing variable amplitude data, which has been derived by authors for a notched geometry, made from a low carbon pressure vessel steel (P355NL1), within the local approaches and linear damage summation framework, and supported by elastoplastic finite element analyses. Several variable amplitude loading are selected and analyzed using alternative configurations of kinematic hardening plasticity models (e.g. Chaboche’s model with distinct constants superposition). The predictions are assessed using available experimental data as well as with predictions made with simplified empiric elastoplastic tools. This paper highlights the difficulties on performing such elastoplastic analysis and compares the obtained results with those obtained using more classical tools for elastoplastic analysis. Fatigue predictions based on elastoplastic analysis made using the Chaboche’s model, with a finite element model, were significantly more accurate than predictions based on simplified elastoplastic analysis. The proposed information has important practical relevance.