The evolutive Masing model and its application to cyclic plasticity and ageing

The cyclic plastic behaviour observed in metals results from the existence and development of plastic heterogeneities inside the material. Starting from this constatation, a general scheme - the evolutive Masing model - is proposed and detailed in some special cases. After briefly describing the structure of the Masing model and its interpretation as an homogenized elastic perfectly plastic constitutive model, some microstructural results are presented, describing the plastic heterogeneities which may develop in a metal under cyclic loading. The evolutive Masing model is then introduced by adding a possible evolution of the local constitutive equations or of the heterogeneous structure. Different types of evolution are then analysed and a special emphasis is laid on the case of yield stress evolution, the effect of which is exemplified in different situations. As a conclusion the introduction of microstructural results in the model is discussed and its role to reconcile microstructure, internal variables and hereditary models is advocated