*RATE DEPENDENT

Define a rate-dependent viscoplastic model.

This option can be used only as a suboption of the PLASTIC, HARDENING=ISOTROPIC option; the PLASTIC, HARDENING=COMBINED option; the PLASTIC, HARDENING=JOHNSON COOK option; the DRUCKER PRAGER HARDENING option; or the CRUSHABLE FOAM HARDENING option to introduce strain rate dependence in the material models.

This page discusses:

See Also
In Other Guides
Rate-Dependent Yield
Classical Metal Plasticity
Johnson-Cook Plasticity
Extended Drucker-Prager Models
Crushable Foam Plasticity Models

ProductsAbaqus/StandardAbaqus/Explicit

TypeModel data

LevelModel

Optional parameters

DEPENDENCIES

In an Abaqus/Explicit analysis this parameter is relevant only for TYPE=POWER LAW or TYPE=YIELD RATIO.

Set this parameter equal to the number of field variable dependencies in the definition of material parameters, in addition to temperature. If this parameter is omitted, it is assumed that the rate-dependent material behavior depends only on temperature. See Material Data Definition for more information.

TYPE

Set TYPE=POWER LAW (default) to specify the Cowper-Symonds overstress power law.

Set TYPE=CHABOCHE to specify Chaboche rate dependence.

Set TYPE=JOHNSON COOK to specify Johnson-Cook rate dependence (this option cannot be used with the crushable foam plasticity model).

Set TYPE=YIELD RATIO to enter yield stress ratios.

If this option is used in conjunction with the CRUSHABLE FOAM option, the static hardening relation must be defined on the CRUSHABLE FOAM HARDENING option.

Data lines to define the overstress power law parameters (TYPE=POWER LAW)

First line

  1. D. (Units of T–1.)

  2. n.

  3. Temperature.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the dependence of the material parameters on temperature and other field variables.

Data lines to define the overstress power law parameters (TYPE=CHABOCHE)

First line

  1. ε˙0. The default is 1.0. (Units of T−1.)

  2. K. (Units of FL−2.)

  3. n.

  4. Temperature.

  5. First field variable.

  6. Second field variable.

  7. Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four)

  1. Fifth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the dependence of the material parameters on temperature and other field variables.

Data line to define the Johnson-Cook rate parameters (TYPE=JOHNSON COOK)

First (and only) line

  1. C.

  2. ε˙0. (Units of T–1.)

Data lines to define yield stress ratios (TYPE=YIELD RATIO)

First line

  1. Yield stress ratio, R=σ¯/σ0.

  2. Equivalent plastic strain rate, ε¯˙p⁢l (or |ε˙a⁢x⁢i⁢a⁢lp⁢l|, the absolute value of the axial plastic strain rate in uniaxial compression, for the crushable foam model).

  3. Temperature.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the dependence of the yield stress ratio on equivalent plastic strain and, if needed, on temperature and other predefined field variables.