WANG Lili, DONG Xinlong. Talk about dynamic plasticity and viscoplasticity[J]. Explosion And Shock Waves, 2020, 40(3): 031101. doi: 10.11883/bzycj-2020-0024
Citation:
WANG Lili, DONG Xinlong. Talk about dynamic plasticity and viscoplasticity[J]. Explosion And Shock Waves, 2020, 40(3): 031101. doi: 10.11883/bzycj-2020-0024
WANG Lili, DONG Xinlong. Talk about dynamic plasticity and viscoplasticity[J]. Explosion And Shock Waves, 2020, 40(3): 031101. doi: 10.11883/bzycj-2020-0024
Citation:
WANG Lili, DONG Xinlong. Talk about dynamic plasticity and viscoplasticity[J]. Explosion And Shock Waves, 2020, 40(3): 031101. doi: 10.11883/bzycj-2020-0024
The researchers in solid mechanics are interested in studying the mechanical response of deformed solids with stress-strain constitutive relationships (referred to as deformation-type constitutive relations), while the researchers in fluid mechanics are interested in studying the mechanical responses of fluids with stress-strain rate constitutive relationships (referred to as flow-type constitutive relations). When the dynamic plasticity of structures and materials is concerned, should it be in terms of plastic deformation or plastic flow? This paper discusses this problem from the macroscopic plastic constitutive theory and the microscopic dislocation dynamic mechanism, respectively, and points out that the plastic constitutive relation belongs to the flow-type viscoplastic rate-dependent constitutive relation, which is suitable for both loading and unloading processes. Therefore, the stress-strain diagram should not be used to describe the plastic loading and unloading processes. The elastic-plastic constitutive relation is the coupling of the deformation-type and flow-type constitutive relations.
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Figure 1. (a) The Hooke’s elastic law (τ=Gγ) described in τ-γ coordinates; (b) The Newton’s viscous law (τ=η$\dot \gamma $) described in τ-$\dot \gamma $coordinates; (c) The Newton’s viscous law (τ=η$\dot \gamma $) described in τ-γ coordinates
Figure 2. Shear slip in a perfect crystal
Figure 3. Slip formations due to dislocation movement.
Figure 4. The macroscopic plastic shear strain ${\gamma ^{\rm{p}}}\left( {{\rm{ = }}\tan \theta } \right)$ caused by the motion of a row of parallel dislocations
Figure 5. Schematics of dislocation barrier
Figure 6. Mises yielding cylinder and Liu’s bell-like fracture surface in principal stress space[14]
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