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:
where is the equivalent creep strain, is the true Von Mises stress an t is the total time. For LAW=USER the creep law must be defined in user subroutine creep.f (cf. Section 8.1).
All constants may be temperature dependent. The card should be preceded by a *ELASTIC card within the same material definition, defining the elastic properties of the material. If for LAW=NORTON the temperature data points under the *CREEP card are not the same as those under the *ELASTIC card, the creep data are interpolated at the *ELASTIC temperature data points. 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.
If the elastic data is isotropic, the large strain viscoplastic theory treated in  and  is applied. If the elastic data is orthotropic, the infinitesimal strain model discussed in Section 6.8.13 is used. If a *PLASTIC card is used for an orthotropic material, the LAW=USER option is not available.
Following lines are only needed for LAW=NORTON (default): First line:
Example: *CREEP 1.E-10,5.,0.,100. 2.E-10,5.,0.,200.
defines a creep law with A=, n=5 and m=0 for T(temperature)=100. and A= and n=5 for T(temperature)=200.
Example files: beamcr.