Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

PSD Analysis Question

Status
Not open for further replies.

Stringmaker

Mechanical
Joined
Mar 18, 2005
Messages
513
Location
US
I'm performing a number of PSD runs on a structure with approximately 1 million DOF and between 0-2000 Hz it has 700 modes. To cut back run time and .rst file size during the mode combination step I am specifying different values of for significance value (command is PSDCOM,SIGNIF,,) and I've noticed that a value of 0.001 and 0.01 for SIGNIF produces nearly identical one sigma displacements and stresses. I think the SIGNIF command is based on covariance values normalized to 1 for the maximum mode if memory serves. All modes with values equal or less than SIGNIF are not considered. What I want to know is there a way to tell how many modes are actually being considered for each different SIGNIF value? I didn't see anything mentioned about this in the output file. Any help would be greatly appreciated.

Thanks in advance,
-Brian
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor

Back
Top