Some Multiaxial Viscoplastic Experiments: Relation to Tensor Functions
The aim of the chapter on experiments is to find as simple a relationship as possible between fundamental invariants of stress, plastic strain and plastic strain rate (usually called equivalent plastic strain, equivalent plastic strain rate and equivalent von Mises stress). It would be desirable that the results lead perpetually to the so-called unique flow curve connecting equivalent stress and equivalent strain for a fixed strain rate and diverse stress trajectories. Such curves have been used extensively for numerical purposes like in FEM codes. In order to be objective as much as possible, no constitutive assumption concerning flow rule is introduced throughout the first part of this chapter.
Then the two constitutive models are calibrated comparing plastic stretching tensors, calculated from their evolution equations, with their experimentally found values. This would clarify admissibility of evolution equations in FEM codes. Experiments were performed in the dynamic testing laboratory of JRC-Ispra, Italy, with specimens made of austenitic stainless steel AISI 316.
KeywordsPlastic Strain High Strain Rate Equivalent Stress Plastic Strain Rate Tensor Function
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