Development of plasticity model for steel ratcheting simulation

The problem of ratcheting, defined as the progressive plastic strain accumulation in cyclic loading, is considered to be one of the unsolved difficulties of plasticity and furthermore fatigue modeling. Towards this direction many models within the frame of constitutive plasticity, based on the well known Armstrong and Frederick (AF) kinematic hardening rule have been introduced. In this paper further implementation of the multiplicative AF kinematic hardening model proposed in ASIP Conference 2007 and by Dafalias et el, is performed more extensively in the area of ratcheting simulation. Uniaxial experimental results, extracted from published results, were used for the validation, as well as for the assessment in terms of its capability to predict ratcheting response in steel alloys. In addition, the results of the commonly used Chaboche model with Threshold term have been compared with the relevant results of the multiplicative AF model, indicating an improved response. This model has been formulated for use in multiaxial loading cases, yet ratcheting simulation in specific published bi-axial results is an ongoing project and is expected to be presented in future works.