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Change normal orientation of brick solids elements

Hello,

 

In need help to change the normal orientation of solid elements, does anybody knows a way how?

This in order to have all equal face pointing in the same direction.

 

Thanks in advance!

 

Casper

6 REPLIES

Re: Change normal orientation of brick solids elements

Hi, Why you need to orient normal of brick solids elements? what kind of loads will you apply? Actually normal orientation is useful when dealing with plate element and especially when you apply pressure on them. For solid elements you can just use the pick / by faces / adjacent faces to apply the loads (if that's what are you doing) You can define a material orientation for the solid elements using a csys system or element csys.
Seif Eddine Naffoussi, Stress Engineer

Re: Change normal orientation of brick solids elements

Hi @SN, thanks for the swift reply!

 

I'm using them indeed to apply pressure loads on them. They are part of a bigger plate element model, for which I use a script to apply pressure on the elements indeed, rather then on the surfaces.

Therefor I would like to incorporate the loading of the solids with pressures in the same script, or run an seperate script afterwards.

I'm using a script to load the elements because it's a rather big model, with location dependant pressures, and 22 loadcases for now.

 

I tried to modify the material orientation of the solid elements, but getting the error that this is only possible for quad or tri elements...

So how would you change it?

 

Could you advice on what's best to use or may be to use an other procedure to apply pressure on the solid elements?

 

Casper

Re: Change normal orientation of brick solids elements

Hi,

 

Here's a macro that may help: it aligns the internal CSys of brick elements to a user specified coordinate system. I coded this a while back because in MSC NASTRAN solid laminates require specific orientation of the bricks, i.e. reordering of its nodes (this is simpler in NX NASTRAN).

 

A few things to know:

- you can view the internal csys of bricks in FEMAP through View Options > Element - Coordinate System > select "Axes"

- the macro will ask you for a CSys and align the bricks "the best it can". I haven't tested it in many strange cases...

- the macro wont work for sphecrical CSys, i can't remember whether it supports cylindrical either, and it is intended for linear hexas, not parabolic.

 

Hope it works!

A. Pavageau

Re: Change normal orientation of brick solids elements

@astrium_tls, That's a nice macro tnx.

 

However, I'm having only parabolic bricks. Luckily the ones I'm interrested in are in a planar shape, so I could manually change them to linear, orientate the csys and convert them back to parabolic.

 

However, what's the catch in converting the macro into a new one that would work with parabolic bricks?

 

Is there actually a way to change the csys manually within femap?

 

Thanks in advance,

Casper

Re: Change normal orientation of brick solids elements

Hi,

 

"Is there actually a way to change the csys manually within femap?"

Not that I know of. The "Orient first edge" commnd could have worked, but it refuses elements other than 2D...

 

"However, what's the catch in converting the macro into a new one that would work with parabolic bricks?"

So because there is no FEMAP command that 'reorients' solid elements, you have to manually reorder the element's node indexes, that's what the macro does. For exemple 01234567 => 15620473 means tilting a brick on its right side. This can be seen in the code at lines 61 to 79.

Writing these for 8node bricks was quite annoying, writing them for 20node bricks sounds even worse!!

 

It's annoying yes, but it isn't hard, just a bit mind-torturing. You would need to do the following modifications:

- add the 12 missing node indexes in the 'matRot' array (lines 61 to 79)

- modify line 239 and indicate to go up to 20 nodes, not 8

- add a line at line43 to also take into account BRICK20 elements

 

AP

Re: Change normal orientation of brick solids elements

@astrium_tls,

 

Ok, thanks. I'll try to convert the macro, if I'll be able before my holiday.