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Modal Participation Factor from Nastran

Creator
Creator

Hi all!

I would like to perform a durability simulation with the modal superposition tecnique. The problem is that I have no idea how to retrive MPFs from Nastran to perform the simulation.

Any suggestions?

7 REPLIES

Re: Modal Participation Factor from Nastran

Legend
Legend

Look at the MEFFMASS output, that is where you will be able to get what you want ...

Re: Modal Participation Factor from Nastran

Siemens Genius Siemens Genius
Siemens Genius

Dear Hen,

 

by the tag I assume you want to do this with LMS Virtual.Lab:

 

In the Load Function Set, select Data Soure > Add a data File

Choose here the NASTRAN file format you have saved the MPF (Virtual Lab can read op2 or PUNCH)

 

BR

 

Michael

 

Dr.Michael Hack
Business Product Line Manager Durability
Simulation and Testing Solutions

Re: Modal Participation Factor from Nastran

Creator
Creator
I see. The problem is that I cannot figure out which nastran statement is required in the .dat file to get MPFs in the .op2 file.

Re: Modal Participation Factor from Nastran

Legend
Legend

Hen wrote:
I see. The problem is that I cannot figure out which nastran statement is required in the .dat file to get MPFs in the .op2 file.

As I said 3 months ago: MEFFMASS is what you're looking for.

 

MEFFMASS(FRACSUM,SUMMARY) = YES would do the trick.  There are more output options for MEFFMASS that can be found in the QRG.

Re: Modal Participation Factor from Nastran

Creator
Creator

In my understanding, the modal transient fatigue analysis requires the time history of the generalized displacements also known as MPFs. The NASTRAN statement you suggested will not give these generalized displacements but  a totally different conceptually output  that has the same name.

Re: Modal Participation Factor from Nastran

Legend
Legend

Hen wrote:

In my understanding, the modal transient fatigue analysis requires the time history of the generalized displacements also known as MPFs. The NASTRAN statement you suggested will not give these generalized displacements but  a totally different conceptually output  that has the same name.


Modal transient response, usefull piece of information!  MPF in MEFFMASS are modal mass participation factors, not "conceptually different", dynamics is stiffness, mass and damping Smiley Happy

 

If you're asking for generalized displacements as you are now, is SDISPLACEMENT(PLOT) = ALL  not what you're looking for? That's what the modal transient fatigue in MSC Nastran uses.  Isn't there anything in the documentation?  Have you asked GTAC? 

Re: Modal Participation Factor from Nastran

Legend
Legend

If you're asking for generalized displacements as you are now, is SDISPLACEMENT(PLOT) = ALL  not what you're looking for? That's what the modal transient fatigue in MSC Nastran uses.  Isn't there anything in the documentation?  Have you asked GTAC? 

Looks like I was right, according to this user who asked GTAC: Can-Modal-Response-Functions-be-obtained-when-running-a-SOL112

 

Next time, make sure to use the proper terminilogy and give us complete information to guaranty better help Smiley Happy