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viscous step

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great2008
Posts: 5
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(@great2008)
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Hi everyone.

I have a question about viscous steps.

How can I simulate a viscous step at a strain rate of 1e-13 without having to run the model for toooooo much time (a weak or more)?

Thanks

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stusapien
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Why don&#8217,t you specify a very large time period for the step, and also a comparable large initial step size?

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great2008
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(@great2008)
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If I specify a very large time period (1e14) would take forever to run the analysis and achieve the amount of deformation that I want. I am thinking that there must be a way to run a model at really low strain rates without having to wait for it a week. If anyoane knows how to do that please let me know.

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stusapien
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If the time period is large (1e14) and the suggested initial time increment is also large (say 1e13) then the solution time should be very short.

For example,

*VISCO
10.e13,1.0e14,1.0e12,2.0e13,

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great2008
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Thanks man,
Your suggestion seems to work so far. Do you have any ideea how to implement a strain rate dependend viscosity or creep in Abaqus?
Cheers

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stusapien
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It depends on the material you are trying to model. Its constitutive behavior may closely match one of the material models in ABAQUS that support viscous and creep effects. If not, then you can implement it as a user material model, or use a third party user material library such as that developed by Jorgen.

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great2008
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I am trying to model geological materials subject tu 400-700 degree Celsius and very low strain rates. There are not really well developed models for such materials therfore I am looking for some materials that may behave in a similar manner and their constitutive laws are better understood. It looks for me that polymers are close enough. Can you please give a refernce towards Jorgen material library or any material that experiences strain rate softening.

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