Abstract
This paper presents a new phenomenological model for describing the main features of the viscoplastic behavior of superplastic sheet metals, namely, strain hardening, softening, and damage. The proposed model is based on a variable strain rate sensitivity index (m-value) measured from uniaxial tensile tests at different strain rates under constant temperature. In this study, the uniaxial tensile tests were carried out at three strain rates (i.e., 10−3, 10−2, and 10−1 s−1) on a superplastic grade AA5083 aluminum sheet alloy. In addition, the volume fractions of cavities at different plastic strain levels were assessed using X-ray microtomography. The performance of the model was investigated by comparing its predictions with the experimental data. In addition, the model was validated with two sets of reference data for AA5083 aluminum alloy and AZ31 magnesium alloy. In particular, it was observed that the new model could predict the flow behavior of these metals more successfully compared with two reference models; nevertheless, it requires minimal experimentation and calculation efforts.
Published Version
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