ANALISI DEL COMPORTAMENTO POST-NECKING IN METALLI REFRATTARI

The identification of strength models starting from the results of a simple tensile test is characterized by some problems related to the development of triaxial state of stress inside the specimen consequent to necking. Moreover, if the material, such the case of refractory metals, is strongly dependent on both strain-rate and temperature, it is not possible to neglect the non-homogeneous distribution of these variables both in space inside the specimen and in time, during the deformation process. Standard methods even if based on numerical inverse approach are not able to guarantee that the results is consistent in terms of deformed shape of the necking zone. To this end, in this work, a methodology for the strength model calibration from instability up to fracture is presented: the idea is to also take into account the deformed shape of the specimen and the variation of the important quantities.