1. Determination of elastoplastic properties

1.1 Definition of elastoplastic behavior

An elastoplastic material is characterized by a flow threshold below which behavior is purely elastic, whereas once this threshold is reached, deformation is no longer reversible. Strictly speaking, the latter is independent of time: it does not change if the load is kept constant, nor does it disappear progressively after discharge. Similarly, the threshold does not depend on the rate of deformation. In practice, however, this is rarely the case, and in reality materials most often exhibit elasto-visco-plastic behavior. In crystallized materials (metals, ceramics, ionic compounds), plastic deformation results from the displacement of crystal defects called dislocations.

At very low temperatures, the stress applied is...