Search:

Please send me a private message if you have not received help yet.

-Jorgen

The website seems to work fine. What info do you need?

-Jorgen

The Three-Network Model from the PolyUMod library would work really well for that type of material.

-Jorgen

You can view the page at http://polymerfem.com/content.php?98-polyumod_dot_com_info

You can view the page at http://polymerfem.com/content.php?97-Advanced-FEA-Polymers-May-2013

Unfortunately I don't have any additional data that I can share at this time.
I can perhaps test your material for you if you are interested...

-Jorgen

I have developed a number of UMATs that can capture that type of response. So it is certainly possible.

-Jorgen

Are you trying to select a material model?
What rubber material are you interested in?
What temperatures and strain levels are you focusing on?
What type of failure mode are you concerned about?
...

The parameter d is basically 1/kappa, where kappa is the bulk modulus.

(Note I don't quite recall if it is 1/kappa or 2/kappa)...

-Jorgen

Material models are usually created based on insight into the micromechanisms creating the macroscopic response.
What material are you studying?

Does your figure show stress relaxation behavior,...

As I mentioned in my message above, MCalibration can solve your problem.

-Jorgen

No need to reinstall the OS. My guess is that you may have some problem with your Virtual Studio software, or the compiler software.

-Jorgen

Oh, yes, of course. You only get the position of the current integration point.

I suspect that there is no easy way to get the nodal coordinates :(
Also, why would you need the nodal coordinates?...

I am not sure how you would create a time varying E in ANSYS (and also, I an still not sure why you trying to do that).

-Jorgen

Can you check if some of the elements get distorted?

-Jorgen

Most FE software has built-in capabilities for finding the coefficients for simple hypelastic models.
The MCalibration software can also do it, and can also handle more advanced material models.
...

Abaqus does that using, if I remember right, a Fourier transform of the frequency domain data.

Another approach is to determine the Prony series using a "direct inverse" approach where you find...

I don't have any data to share :(
But I can test the material for you...

-Jorgen

I don't have experimental data to share, but your list of properties seems reasonable.
Brain tissue has been studied a lot, so you should be able to locate a lot of info in the literature (if you...

Well, the theory of hyperelasticity is based on strain energy density. There are other non-linear elastic models that are not based on a strain energy density, for example hypoelasticity.

Note...

Are you sure that is right?
A negative internal energy would suggest that the fabric is not at equilibrium at the start of the test.

-Jorgen

Your printout includes the statement:


That error indicates that you are using a 64-bit compiler on a 32-bit computer.

-Jorgen

I don't have much experience with vuhard subroutines. Perhaps someone else can provide more feedback.

-Jorgen

You are asking a low of excellent questions that are quite difficult to answer in a sentence or two.
I recommend that you take one of my training classes for detailed answers.

-Jorgen

If you have problems making these linear viscoelastic models work, then you may want to check out the MCalibration software to better calibrate and explore the material model response.

-Jorgen