Modeling linear viscoelastic solid in abaqus
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 calculate these parameters? Any other method than Prony series?
It sounds like you are doing it about right. If you have problems making it behave as expected, then I would do it the other way around. Select the linear viscoelastic parameters and see how the model will respond.
You should consider trying the [URL= https://polymerfem.com/articles/material-model-calibration ]MCalibration [/URL]software. It is excellent that working with viscoelastic material models.