Structural damping coefficient.(rad/sec)

- October 20, 2018 at 10:02 am
  
  Abdelmoniem
  Subscriber
  
  Hallo all, i wanted to ask about the structural damping coefficient in the full harmonic analysis. why its unit is rad/sec and which value of omega should i input then? is it the value where the structural damping becomes equivalent to the viscous damping ?.
  
  and why i can't input the loss factor ? i know it is equal to damping ratio multiplied by 2 but i don't find where to input it.
  
  i would be very thankfull if anyone can help.
  thanks alot
- October 22, 2018 at 4:16 pm
  
  Sandeep Medikonda
  Ansys Employee
  
  Hi,
  
  Structural damping enables you to incorporate hysteretic behavior due to internal material friction by specifying a coefficient on the stiffness matrix. In this type of damping, the damping force is proportional to the displacement rather than the velocity as in the other damping options. Refer to this section from the manual.
  
  Regards,
  Sandeep
- October 25, 2018 at 10:17 am
  
  Abdelmoniem
  Subscriber
  
  thank you Sandeep. I can understand that the equation becomes mx''+K*x=f und that K*=k(1+i*eta). So if the coefficient of stiffness is(1+i*eta) then its value is unitless. in Ansys in the input port it is required to enter the value of structural damping coefficient in rad/sec. attached pls find the pic. of that. so i don't know why should it be in rad/sec..
  
  best regards ,
  Moniem