Erik Kostson
Ansys Employee

See that discussion Peteroznewman explains what Ansys does when you give a frequency of interest (say the freq. of your dominant mode of interest that will be excited – frequency_given) and a damping ratio (damp_ratio_given).

As he says, it calculates 
beta = (2*damp_ratio_given)/(2*PI*frequency_given).

So if you want a damping ratio of 0.01 at your frequency of interest (say 20 Hz) that are the values you put in. So beta will give you then 0.01 damping at 20 Hz that all the equation says.