Elasto-viscoplastic finite element analysis models irreversible deformation as a rate-dependent process. Plastic flow develops over time rather than being represented only as a rate-independent constraint at a yield surface.
How It Works
The source treats viscoplasticity first in one dimension and then in two-dimensional finite element problems. The implementation view is time-step based: strain increments, stress updates, viscoplastic strain rates, and material state variables are advanced over a finite time interval.
Viscoplastic formulations can also be used as a numerical regularization of plastic flow. The finite element program still assembles internal forces from stress states at integration points, but the constitutive update depends directly on the step size and rate parameters.
Why It Matters
Rate dependence is important when deformation speed, creep-like effects, or numerical regularization of sharp plastic transitions matter. It also forms a bridge to Transient Dynamic Elasto-Plastic Analysis, where inertia and time integration interact with material inelasticity.
Solver Checklist
Define the viscoplastic strain-rate law and rate parameters.
Store accumulated viscoplastic strain and other hardening variables at integration points.
Select an explicit or implicit update for the material state.
Make the global time increment consistent with both stability and constitutive accuracy.
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