I had performed an ansys simulation for simulating the effects of pdms on SAW attenuation. I thought that the effect of viscoelastic properties on wave changes with frequency and hence, for my frequency of interest (i.e 100MHz), I found the youngs modulus (550MPa) and poissons ration(0.4).
Now, I gave the above value of youngs modulus and poissons ratio instead of the prony series for the simulating the effects of pdms on acoustic wave, and I did get attenuation of 30% (normal component of wave) corresponding to various lengths (250 micro.metre) and heights (250 micrometre) of the pdms. So I thought that this approximation is fairly accurate instead of running the time consuming prony series nonlinear simulation.
But I read through a document (Dynamics and response of polymer-coated surface acoustic wave devices by Martin et.al) and came to understand that the effects of attenuation does arise due to the loss modullii of shear and bulk components. And I think the static value of youngs modulus which I had entered in the simulation will only have the real component(storage modullii). So now I am confused.
Could some one please tell me :
1)Whether my understanding about the loss modullii on the attenuation is correct.
2) If the attenuation is only due to loss modulii, then why did the ansys simulation gave the amplitude attenuation?