for long-term modulus of viscoelastic material

[lwn]

Dear All:

I have a question. When we use frequency test data (from DMA) for viscoelastic model in ABAQUS. We have to give the long-term modulus. What modulus should be given as long-term modulus, at very low frequency?

Thank you.

David

[Jorgen]

Hello David,

The long term modulus is given by the modulus at very low frequency. You can also obtain the long-term modulus, of course, from a single stress relaxation test.

- Jorgen

[sq]

One quick additional note- some materials creep or stress relax seemingly forever. IF the timescale of the event of interest (i.e., what you're trying to simulate) is short compared with the longest timescale or lowest frequency of your experimental data, there is some flexibility in setting the long term modulus. That is, the experimental data need not actually plateau so long as the behavior is adequately captured in the frequency range you need to model.

[lwn]

Hi, Thank you. I am doing some numerical simulation of polymer composite.

david

[mohsen]

Hello David,

The long term modulus is given by the modulus at very low frequency. You can also obtain the long-term modulus, of course, from a single stress relaxation test.

- Jorgen

Hi Jorgen
in many papers only storage modulus and loss modulus (E+jE") are given
without any dependence to frequency
can I model this material with ABAQUS?
I cantfind any long term modulus in these papers.
THANKS

[Jorgen]

Even for a simple linear viscoelastic (LVE) model, the storage and loss moduli are frequency dependent, so I don't see how you could calibrate a viscelastic model without additional info.

What you can do, however, is to use the storage modulus (E') to calibrate a hyperelastic model (such as the neo-Hookean model) and then use that model for your simulation.

- Jorgen