# Modeling linear viscoelastic solid in abaqus

Hello Experts!

I am a beginner in Abaqus as well as Viscoelastic materials. So my question may sound like a very basic or rookie question.

I am trying to model a viscoelastic material which has one linear elastic soring with G1 and a spring in parallel with a dashpot, G2 and Viscosity, eta .

A value of Tau(s) = eta /(G1+G2) = 0.99 s

Other available parameters-

Time independent bulk modulus K

Time dependent Youngs modulus E(0) and E(inf)

And Poisson ratio nu(0) and nu(inf) are available.

I am trying to develop this model in an attempt to simulate nanoindentation process.

First attempt made was with abaqus Prony series parameters,

g_i , k_i and Tau_i by using single set of values as follow-up

g_i = G1/(G1+G2) = 0.099, since g_i are normalized values

k_i = 0.99, K is time independent, but abaqus wont take values >= 1

Tau_i = 0.99 s, used as available

Used E(0) and nu(0) for initial deformations.

I got a set of results which dont seem reliable.

I think I have gone wrong with those parameters.

How should I go about it? Any other method than Prony series?

Hi Dear Experts.

My name is Saeid. Im working on modeling some kind of Polymer materials named Polyurea. I have Hyperelastic 9 Parameters moony rivilin and Viscoelastic prony series properties of material elicited from an article. the problem is that, ABAQUS doesnt support 9 parameters moony rivilin and only takes 3 parameters of them (or maybe Im wrong and we can introduce all 9 parameters to ABAQUS, then how?) and it doesnt give enough acceptable accuracy to us. now my question is if there is any external program that can make this problem fixed? my secound question is that if there is any way to convert moony rivilin parameters to polynominal 3 order parameters so that ABAQUS would be able to use them? or any other way that can Help us to fix our problem?

Thanks in advance.

If you have problems with the accuracy, then I recommend that you try the [URL= https://polyumod.com/ ]PolyUMod[/URL] library. It contains material models that are more accurate for Polyurea.

-Jorgen

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