Rubber component for vibration elimination

[Carlos]

Hi everyone,
i´m using Ansys to model a black rubber grommet, used to isolate a support from compressor vibrations. There´s an option to automatically fit the experimental shear- and bulk-modulus vs. time to a Prony model, and I think it would be accurate enought to compute them as
G=E/2(1+v)
K=E/3(1-2v)
and consider v (Poisson´s ratio) constant. So my questions are the following:
1. are my supposition right under constant temperature?;
2. to compute E vs. time, is it enough to realize a compression experiment over a cylindrical specimen?;
3. shall the deformation rate in the experiment be 59Hz/2, if this is the frecuency I want to attack?.
Many thanks for your comments.

Carlos.

[Jorgen]

Hello Carlos,

Just to make sure I understand, are you planning on performing uniaxial experiments to obtain the shear and bulk modulus as a function of time (i.e. Prony series)? If so, I would assume a constant value for the bulk modulus (and not assume a constant value for the Poisson's ratio), and then calculate G(t) using the equation that you listed.

2. To calculate E(t) you will need to perform either cyclic loading experiments at different frequencies, or monotonic loading experiments at different strain-rates.

3. You will need to perform the experiments at a range of frequencies. It is a good idea to perform the experiments at similar rates to what the real product is exposed to.

Best of luck,
Jorgen

[Carlos]

Thanks Jorgen.
I only wonder if considering the bulk modulus constant is because I am considering incompressibility.
Best regards.

Carlos.