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Role of strain-rate sensitivity in the crystal plasticity of hexagonal structures. (English) Zbl 1105.74007

Summary: In the first part the stress and strain-rate responses of hexagonal crystal structures are examined when slip is viscoplastic according to a power law. The stress and strain-rate equi-potential surfaces are constructed and discussed as a function of the strain-rate sensitivity index \(m\). The second part of this paper deals with the case of linear viscous slip; i.e., with the case when \(m\) is equal to one. A simple analytic solution is presented to obtain the deviatoric stress state for a given strain-rate. It is shown that the plastic spin is not zero for \(m=1\) in hexagonal crystal structures, contrary to the cubic case where the plastic spin vanishes. In addition, the rate of texture evolution in simple shear of a magnesium polycrystal is examined as a function of \(m\).

MSC:

74E15 Crystalline structure
74C10 Small-strain, rate-dependent theories of plasticity (including theories of viscoplasticity)
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