Modeling Viscoelastic model in Ansys

[venkateshraja]

Dear All

I have the value of comples shear modulus in the form of G=a+bi, how to model in ansys(How material properties has to be defined for input?)

[Jorgen]

Typically, you need to know one of the following:
-stress relaxation behavior
-creep behavior
-storage and loss modulus as a function of freq

I am not sure what you mean by G=a+bi

-Jorgen

[JoseTellez1987]

Hi

I've conducted a series of uniaxial tensile tests on live tissue from which I obtained stress relaxation and creep curves.I've also obtained a prony series for the stress relaxation tests. Now I intend to use this data to build a viscoelastic model in ANSYS but i'm not sure how to apply my experimental results to it.

I did explore the GUI prony series viscoelastic model on ansys 11 but I'm not sure if I should use shear response model or volumetric response ?? what is the real difference between the two anyway???. Can I use tensile tests results even if the program simulates a shear response???

thank you for your time

[Jorgen]

The easiest way to handle that situation is to assume that your material has a constant bulk modulus, and therefore the shear viscoelasticity is the same as the uniaxial viscoelastic prony series. For many materials that is an appropriate simplification. Using this approach you can determine the linear viscoelastic material which you can then use to predict the response in any loading mode.

-Jorgen

[JoseTellez1987]

Thank you , your answer has been most helpful , however do you have any reference that I could quote on the issue ??? sorry for your inconvinience

[Jorgen]

I don't have any reference with me at the moment, but it is a common strategy that is probably not too hard to find a reference to. I recommend that you check out some of the standard linear viscoelasticity books...

-Jorgen

[JoseTellez1987]

I'll do that thank you anyway