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inertia relief

how do you perform inertia relief analysis in nx9? thanks.

8 REPLIES

Re: inertia relief

Siemens Phenom Siemens Phenom
Siemens Phenom

Inertia Releif is activated via PARAM, INREL. Setting this to -2 requests automatic inertia relief (no SUPORT entries needed). A setting of -1 is manual (user specifies SUPORT dof).

 

See the User's Guide and the Quick Reference Guide for more details.

Re: inertia relief

Creator
Creator

If using param inrel -1, how do I specify SUPORT entries within the NX interface though (specifically, NX10)?

 

I can turn on the checkbox for "inertia relief", edit the parameters to include inrel -1, but the software doesn't do a very clear job in telling the user how to add these entries in.     I tried to do it manually by specifying key-in text under solution-->bulk data-->DOF sets --> user defined text, or dropping it into the .dat file at runtime, but neither of these options neemes to work.

Re: inertia relief

Siemens Phenom Siemens Phenom
Siemens Phenom

On the Solution dialog, toggling on the Inertia Relief (INREL) checkbox will cause PARAM, INREL, -2 to be written to the input deck. This requests automatic inertia relief.

 

To define manual inertia relief, leave this toggle off. On the Solution Bulk Data tab:

  1. Create a Solution Parameters modeling object and set INREL to -1.
  2. Expand the DOF Sets group and create a Fictitcous Support (SUPORT) dof set to define SUPORT DOF.

 bukl.png

 

 

Re: inertia relief

Creator
Creator

Thanks!

 

How do the two parameter options (automatic vs manual) differ from each other, in terms of when when I should be using one or the other?   The Nastran manual illustrates how do denote either in the .dat file, but it doesn't talk about which one is more appropriate for what situation.

Re: inertia relief

Creator
Creator

Really appreciate the input.   I'm surprised I didn't get a notification for your reply on this thread.    I just happened to stumble back in regarding a different topic.

Re: inertia relief

Siemens Phenom Siemens Phenom
Siemens Phenom

Automatic inertia relief (INREL = -2) only works for models with 6 rigid body modes.

 

Use automatic for free-free models and manual for anything else.

Re: inertia relief

Creator
Creator

thanks!

Re: inertia relief

Creator
Creator

Hello I know this is a bit too delayed, but with the manual INREL and SUPORT set up, do I need to specify PARAM GRDPNT to be a specific point where I need the inertia relief applied?