ANSYS viscoelastic curve fitting

[juan]

Hello,

I'm trying to modelate a viscoelastic plastic in ansys

In another message, Jorgen_Bergstrom said that the easiest way is to perform a stress relaxation experiments, but in a stress relaxation test you obtain a stress relaxation & time curve, what is the method to transform this curve into a shear & time or bulk & time curve in order to introduce in the Ansys viscoelastic curve fitting ,to obtain the Prony series parameters??

Thanks in advance.

Juan

[Jorgen]

Hi Juan,

Once you have the stress relaxation results you basically are done. Simply take the stress response and divide it with the applied strain amplitude, in order to get a stress realaxation modulus.

Then all you have to do is to find the most appropriate parameters for the prony series that fit the experimental data curve. Many FE programs (for example ABAQUS) have automatic tools to find the prony series from the experimental data. I dont' use ANSYS that often so I cannot give specific direction for how to perform this last step using ANSYS. Also, as an option, you can find the material parameters rather easily using a minimization algorithm in Matlab or Mathematica.

Jorgen