A rate-independent crystal plasticity model with a smooth elastic–plastic transition and no slip indeterminacy
Résumé
A new crystal plasticity constitutive model is proposed that combines, for the first time, the following features: (i) multi-criterion formulation, (ii) exact strain rate-independence, (iii) absence of a consistency condition and (iv) smooth elastic–plastic transition. It is characterised by the existence of a rate-independent overstress that removes the usual possible indeterminacy of simultaneously activated slip systems. The performance of the new model compared to a reference crystal plasticity model by Méric and Cailletaud (1991) in its quasi-rate-independent limit was evaluated in the case of two significantly different materials, namely single crystalline copper and a nickel-based superalloy at room temperature. The provided material point simulations of complex loading paths and large scale finite element simulations do not show any spurious effect of the model, provided that the overstress remains small enough. The improved computational efficiency of the model is discussed.