How to use MDAMP

- October 10, 2023 at 2:21 pm
  
  chonkiat.lee
  Subscriber
  
  Hi, I would like to make the highest peak goes higher... but I have tried the command many times but then still not working...
  
  mdamp,4,,,,0.01
  Is my command not correct? No matter how I change the number, the curve not changing at all...
- October 10, 2023 at 3:03 pm
  
  Erik Kostson
  Ansys Employee
  
  Hi
  First it needs to be used with MSUP (mode super pos.) analysis (say harmonic), so place the command snippet there in the harmonic analysis (not under the modal).
  I would try to look at MDAMP in the help apdl command reference guide.
  Also try MDAMP,1,0.1,0.1,0.1 to see if the first ~ 1-3 peak go down.
  All the best
  Erik
- October 11, 2023 at 5:02 am
  
  chonkiat.lee
  Subscriber
  
  Thanks Erik.
  
  I am using MSUP for random vibration. I can see the peak will go down... however, I want to make the second peak amplitude going up by changing to very small damping ratio. I notice that we can dampen the peak but only able to increase the peak slightly even we use very small value of damping ratio.
  
  Do we need to use global damping ratio when we use mdamp?
- October 11, 2023 at 8:38 am
  
  Erik Kostson
  Ansys Employee
  
  Hi
  See the help manual on all different forms of damping.
  1.2. Damping (ansys.com)
  
  If you are not able to open the links, refer to this forum discussion: How to access the ANSYS Online Help
  Guidelines for Posting on Ansys Learning Forum
  Hope that helps
  Erik