Defining Viscoelasticity from experimental data

[kevoman]

I have experimental stress (xx,yy,xy) vs strain (%) data in which want to use them to define viscoelasticity.

Any ideas how to define viscoelasticity given my experimental data. Can I use Prony series (g,k,t coefficients)? If yes, how?

Much help is appreciated!

thanks
kevin

[Jorgen]

I am a bit confused: how did you get that experimental data?
If you performed a uniaxial tension experiment (as an example), Syy and Sxy should be 0. How can you have three stress components and only one strain component?

-Jorgen

[kevoman]

I'm sorry, it's a biaxial test

[Jorgen]

I still don't quite understand. You mentioned that you have 3 stress terms as a function of one strain. Exactly how was the strain applied? Was StrainXX and StrainYY equal?

-Jorgen

[kevoman]

Yes, biaxial test with equal strain values for both x and y directions.

[Jorgen]

Did you get the same stress in the xx- and the yy-directions?
Do you have stress-strain data at different strain-rates?
Do you have stress relaxation or creep data too?
What FE software do you use?
Can you run additional experiments?

-Jorgen

[kevoman]

Did you get the same stress in the xx- and the yy-directions? - No, different in the xx and yy directions. I'm testing a biological material (membrane)
Do you have stress-strain data at different strain-rates? - Yes, at different percentage strains (1%,2%... - 19%,20%) with corresponding Sxx, Syy and Sxy values
Do you have stress relaxation or creep data too? - Nope
What FE software do you use? - Abaqus 6.9 EF
Can you run additional experiments? - Not at the moment

Kevin