Large # of Subcases - Way to output case w/ Max Stress in a Element?

[score33]

Hi,

I'm working with a model that I want to apply a large number of loads cases to. The intent is to find the load case that gives the worst case for the structure then design to that load case.

Currently I export the *.f06 to excel, then run some macros to determine the worst load case.

Just wondering if there is a better way to do this. For example, can Nastran monitor the von Mises stress in a certain element and tell me what load case gives me the worst results?

 

[Onda]

I don't think there is another possibility inside Nastran.
You could ask for a punch file with only the stress of a group of element of interest for all sub cases and then post process the punch file with a macro, a vba application, a fortran code or whatever.
The punch file is much easier than the f06 file to post process.
To make a punch file you have to insert in each sub case or on top of all subcases:
STRESS(punch,vonmises,center)=n
where "n" is the set of element of interest.
If you want post process all elements:
STRESS(punch,vonmises,center)=all.

Onda

 

[jodin38]

It depends on which preprocessor you are using.

There is an option, for example, that I have used in FEMAP v9.3 where you can run multiple load sets, and then ask for an 'envelope plot' showing both the maximum stress from the critical load case and also which load case is producing the maximum stress.

 

[AbhiMorey]

Probably the simplest way to achieve what you want to do would be to use MSC.Explore if you are using Patran as the post-proc. It is in Patran's Tool's menu.

It will let you select the elements and result type for which you want to do an envelope and find out the critical cases from a number of subcases even across multiple result files. It has also options to set thresholds or to not include certain loadcases and a plethora of other very handy and useful options.

I only just recently stumbled across it and it has made enveloping and/or finding min/max across results extremely easy!