Figure 8.12: Viscoplastic Behavior in a Rolling Operation
Rate-Dependent Plasticity (Viscoplasticity)
The TB,RATE command option allows you to introduce the strain rat e effect in material models to sim-
ulate the time-dependent response of materials. Typical applications include metal forming and micro-
electromechanical systems (MEMS).
The Perzyna, Peirce, Anand and Chaboche material options (described in Rate-Dependent Plasticity in
the Mechanical APDL Theory Reference) are available, as follows:
- Perzyna and Peirce options
Unlike other rate-dependent material options (such as creep or the Anand option), the Perzyna and
Peirce options include a yield surface. The plasticity, and thus the strain rat e hardening effect, is active
only after plastic yielding. For more information, see Perzyna and Peirce Options in the Material Ref-
erence.To simulate viscoplasticity, use the Perzyna and Peirce models in combination with the TB command's
BISO, MISO, or NLISO material options. Further, you can simulate anisotropic viscoplasticity by com-
bining the HILL option. (See Material Model Combinations for combination possibilities. For example
input listings of material combinations, see Material Model Combination Examples (p. 216) in this
guide.)For isotropic hardening, the intent is to simulate the strain rat e hardening of materials rather than
softening. Large-strain analysis is supported.- Exponential Visco-Hardening (EVH) option
The exponential visco-hardening (EVH) rate-dependent material option uses explicit functions to
define the static yield stresses of materials and therefore does not need to combine with other plastic
options (such as BIO, MISO, NLISO, and PLASTIC) to define it. For more information, see Exponential
Visco-Hardening (EVH) Option in the Material Reference.- Anand option
The Anand rate-dependent material option offers a unified plasticity model requiring no combination
with other material models. For more information, see Anand Option in the Material Reference.Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationNonlinear Structural Analysis