hello, first post here. I seen all the great responses, coupled with the slow responses I usually get from ANSYS support made me register.

Anyways, heres what Im trying to do. I am trying to model a very soft Silicone, which will be used as a vibration damper. I was doing a simple analysis using just the shear modulus, damping ratio, and a completely guessed youngs modulus. It got me a little ways, but not far enough. I would like to model this as a viscoelastic material.

I have read: Prony_Series_Conversion.pdf and am just a little confused. I can get the Transmissibility, T, of the material, which is the ratio of dynamic to loss modulus (G/G) as a function of frequency. Based on that, I took the two relations and divided them. I then created a function F, which is a function of variables g, tau, and constant T.

This eliminates G0 from the equations, giving me 1 equation, 2 unknowns. Initially, I just assumed N = 1, and tried using a Conjugate Graident Method, which tries to minimize the function, I wrote years ago to get the values for tau_1 and g_1. Since I moved everything from one side, the function should have a minimum at 0. From this, I figured I could go back to the G equation, and back substitute for G0.

However, this does not work at all for some reason. I am wondering, how does one choose N? Can we go into a little more detail in the optimization of these constants? I can get G, and G as a function of freq, but like a few other posts Ive read, I cant figure out how to get the Prony constants.

Thanks a lot,