Jump to content
meeranaskarali

Inputs for Frequency response analysis using random PSD data

Recommended Posts

In a random frequency response analysis, the input is in PSD in (m/s2)2/Hz and RMS value in m/s2. I need to perform a random vibration analysis in Hypermesh using Optistruct. How we should input PSD and RMS values. What load collectors/cards should we use?.


Next question is regarding units, if Im using mm,Tonne,Newton units. Then how should i convert the PSD data in (m/s2)2/Hz to compatible units.


Share this post


Link to post
Share on other sites
Guest

Hi,


 


You can input PSD through RANDPS and RANDT1 where RANDPS hold the PSD specifications and RANDT1 holds the PSD loading Vs frequency data.


 


RMS is output from random response analysis and not given as input in optistruct.


 


To convert PSD to mm u have to multiply by gravity


Share this post


Link to post
Share on other sites

Hi Prakash


 


Thanks for the reply. I have given input using RANDPS card only. I couldnt find a load card with RANDT1 in optistruct profile.


 


Regarding units conversion If i have an input ASD of 0.0298 (m/s^2)^2/Hz. To convert it into compatible units of (mm/s^2)^2/Hz. I should multiply with 9810 mm/s2.


Then it will be equal to  0.0298*9810 = 292.3 (mm/s^2)^2/Hz. Is this correct and what you meant.


My unit system is mm, N, Tonnes


 


Regards


Meeran

Share this post


Link to post
Share on other sites
On 11/11/2014 at 11:03 AM, Prakash Pagadala said:

 

You can input PSD through RANDPS and RANDT1 where RANDPS hold the PSD specifications and RANDT1 holds the PSD loading Vs frequency data.

 

 

 

 

 

 

I couldn't find RANDT1 card. I am using HM13.0 & 14.0 

 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
You are posting as a guest. If you have an account, please sign in.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...