Using Correct Damping in Model Answered

Hi everyone.

I am simulating ultrasound through Titanium grain structure and to get an accurate representation of how the wave attenuates through the material, I need to consider the damping of the model. However, I am not sure how to select the appropriate values.

c    Crystal Stiffness properties
symb c11 = 160e9
symb c12 = 90e9
symb c13 = 66e9
symb c33 = 191.7e9
symb c44 = 46.5e9
symb rho = 4430
c ***********************************************************************************************************
c Titanium Material
c ***********************************************************************************************************
     type lean
     wvsp off
     prop titm $rho
     $c11     $c12     $c13     0.0     0.0     0.0   $c11
     $c13     0.0      0.0      0.0     $c33    0.0   0.0
     0.0      $c44     0.0      0.0     $c44    0.0   $c44
do loopI I 1 $nmat 1
    copy titm matr$I
    axis matr$I matAx$I  
    rdmp matr$I  $freqdamp db .3  1.2  700000. 1. 0.01
end$ loopI

Where I have included my rdmp line of code. I have no idea how I can implement the proper longitudinal and Shear  Q Factor. These values of .0.3 and 1.2 I have just chosen at whim. 

And from the command help I need to satisfy a range of options
rdmp    matname centfreq option dilatation shear frequency expv distance exps

Any help would be greatly appreciated. 

Thanks

Dave :)