Computationally-efficient Non-linear kinematic Models to Predict Multiaxial Stress-strain Behavior under Variable Amplitude Loading

The best multiaxial fatigue damage models require the knowledge of both stress and corresponding strain histories to quantify damage. Under variable amplitude (VA) non-proportional (NP) loadings, efficient correlation between multiaxial stresses and strains requires incremental plasticity models including non-linear kinematic (NLK) hardening. In this work, the formulation of the main NLK models is unified in a generalized equation, represented using engineering notation in a reduced-order five-dimensional space that may lower in half the associated computational cost. NP tension-torsion experiments with 316L steel tubular specimens are conducted to validate the proposed approach.