Learning Forum

[Emperor]

Hello to all, 

I am working on the structural simulation of hyperelastic models and I have some questions. Concerning the model of Neo, I have that the parameter d is the incompressibility of the material. For compressible material I saw that we could put d=0 or in the energy equation:

[peteroznewman]

You cannot set d=0. You must set d = 2/K where K is the Bulk Modulus of the material.

[Emperor]

How do I get the mass modulus of the material? I have a hyperelastic material for which I only have the shore hardness and the density. Thanks to the shore hardness I could deduce the Young's modulus of the material (Gent's formula) then the initial shear Go. So I chose a Neo-Hookean model with a value of mu. But to find the parameter D1, I wanted to put the value of 0 for the incompressible material. Is it the same "d" or is it different?

T

[peteroznewman]

There is an equation that computes the bulk modulus if you have the shear modulus and the Young's modulus. That equation is coded into the Isotropic Elasticity material model in Engineering Data.

[Emperor]

thanks for your answer.
So in my case I calculate the bulk modulus as follows
then I calculate d=2/k = 2/487.67 = 0.0041
and I enter the value in Neo's model as follows:
it is the same d (there is no difference between the lower case d and the upper case D?)

[peteroznewman]

Yes, I believe that is all the same parameter.

[Emperor]

thank you for your answers best regards.