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*CREEP

Keyword type: model definition, material

This option is used to define the creep properties of a viscoplastic material. There is one optional parameter LAW. Default is LAW=NORTON, the only other value is LAW=USER for a user defined creep law. The Norton law satisfies:

| (10)

where is the equivalent creep strain and is the true Von Mises stress. For LAW=USER the creep law must be defined in user subroutine ucreep.f.

All constants may be temperature dependent. The card should be preceded by a *ELASTIC card within the same material definition, defining the isotropic elastic properties of the material. For LAW=NORTON the temperature data points under the *CREEP card must be the same as those under the *ELASTIC CARD. If a *PLASTIC card is defined within the same material definition, it should be placed after the *ELASTIC and before the *CREEP card. If no *PLASTIC card is found, a zero yield surface without any hardening is assumed.

First line:

- *CREEP
- Enter the USER parameter and its value, if needed

Following lines are only needed for USER=NORTON (default): First line:

- A.
- n.
- Temperature.

Use as many lines as needed to define the complete temperature dependence.

    Example:

    *CREEP
    1.E-10,5.,100.
    2.E-10,5.,200.

defines a creep law with A= and n=5 for T(temperature)=100. and A= and n=5 for T(temperature)=200. The card must be preceded by an *ELASTIC card defining the elastic properties for exactly the same temperatures.

Example files: beamcr.

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