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# viscoelasticity in Abaqus using creep data

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Posts: 6
(@koerma)
Active Member
Joined: 16 years ago

Such as

Waht type of standard or free models are exist in abaqus that are nonlinear for elastic and viscoelastic response.

Posts: 3998
(@jorgen)
Member
Joined: 5 years ago

Here are a few that I remember on top of my head:
- Two layer viscoplasticity
- Drucker-Prager
- Johnson-Cook
- Standard metal plasticity with rate-dependence.

Note that none of these models were developed for polymers.

- Jorgen

Posts: 6
(@koerma)
Active Member
Joined: 16 years ago

Quasi Linear

Jorgen

I think some of the models you have mentione in previous post are for the plasticity. I have little confused, can someone make clear explanaiton on viscoelasticity, As far as I know Abaqus uses linear viscoelastic formulation as:

stress(t)=integral( time dependent relaxation x time dependent shear strain)

Nonlinear effects can be added using different formulations, for example modifed superposition or QLV (Quasi Linear Viscoelasticity) In QLV instantenaous elastic response added into stress representation as:

stress(E,t)=integral ( relaxation mod X instantenous elastic response funct X time dependent shear strain)

Now nonlinearity included in instanteneous elastic response function which may be modelled using energy functions where hyperelasticity (Ogden , Mooney-Rivlin Yeoh, Arruda Boyce etc) enters into formulations.

uppss I have lost myself in that point,

when we use abaqus to model viscoelasticity with hyperelasticity option, are we following Quasi Linear approach ? is Fungs QLV mentioned in somewhere in Abaqus documentation.

Posts: 3998
(@jorgen)
Member
Joined: 5 years ago

You are right that the models that I mentioned are plasticity models that contain time-dependent effects.

I am not sure I understand your description of Fungs QLV method. Can you provide a reference?
The way Abaqus implements viscoelasticity is described in detail in the theory manual. Take a look and see if it is what you are looking for.

- Jorgen

Posts: 2
(@Mautschke)
New Member
Joined: 10 years ago

HELLO, How are you? i am eng. rund, i am using abaqus to model viscoelastic bridge, i input the data for creep volumertric test data like this long term normalized bulk compliance =8.172 and jk= 6.9552,7.2856,7.4928,7.6384,7.7728,7.868 and t=144000000,288000000,432000000,576000000,720000000,864000000 sec. but i have errors please tell me if the input data are correct

Posts: 3998
(@jorgen)
Member
Joined: 5 years ago

What error message do you get? Those are very long time values. It would be useful to have both long and short times.

-Jorgen

Posts: 2
(@Mautschke)
New Member
Joined: 10 years ago

sorry for being late, the error is that the some of relaxtion must be less than 1

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