How to flip shell surface normal direction in Inventor?

[jack_melling9Y6KW]

I am modelling a vessel in shell elements in Inventor for the purpose of doing an FEA on it using Nastran. When applying a hydrostatic load or internal pressure load, the shell wall and hemispherical heads have different shell/face normal directions. This causes the positive pressure direction to be in different directions. Other than applying as two seperate load cases, is there a way to flip the surface normal direction in Inventor? Something that i know is very easy to do in other software I have used. 

Inventor 2024. 

[kacper.suchomski]

Hi

Construction environment or body repair environment.

[jack_melling9Y6KW]

OK,  I have worked out how to activate the construction environment in the applications options and have been able to reverse Reverse Normal of the face using Construction editor. 

However, when I update the Nastran model, the normal properties are not brought in to the load properties. My understanding is that if i change the positive normal direction of a face in the part, the direction of the load should change in Nastran assembly model.  

Is there a better way to do this? 

[kacper.suchomski]

Why don't you just change the sign of the load value (+/-)?

[jack_melling9Y6KW]

I could, but i have a number of faces assigned one pressure. I would have to assign some of them with +ve pressure and some of then with -ve pressure just to get the pressure to be in the same direction. 

This then makes it diffiicult when i have a number of subcases where i have varying load combinations. 

In other software i have used, a simple right click and "flip normal" solves this issue - similar to flipping the normal of workplanes in Inventor. 

[kacper.suchomski]

Attach your files.

[jack_melling9Y6KW]

This is a basic test assembly I made to replicate the issue - If you change the normal direction of the spherical head, it does not change the direction of the load in the Nastran model. I believe these should be related. 

For this specific test model the default normal directions were in the same direction so one pressure load works fine. For my vessel model (which i cant distribute) the Head and the Shell have opposite default normal directions. This therefore causes the issues im having. 

Interested to see what you think.

I may just need to ensure normal directions are in the same direction before bringing the models into Nastran - but this isnt very practical - I havent tried to see if this fixes the issue yet. 

[kacper.suchomski · Accepted solution]

Hmmm 🤔

It works for me.

[jack_melling9Y6KW]

Ok great, this gives me confidence that its possible. I will keep playing with my model to get it to work. Might be doing something wrong. 

Thanks for your help.