Application of a Force

[ViniciusV]

I know this may sound stupid but I've been working with Ansys for 2 years and I never faced myself with this problem, since the stress were always applied on surfaces.

This time I want to apply a force at the center of a circle, not on it's surface. How can I do that? I thought of using Remote Force since I know the correct coordinates but I think that this remote force carries a moment with it.

I appreciate any suggestion. Thanks.

 

[Calcul8it]

In Ansys Classic I would select that center node (I assume you mean the center of the circle disc?) graphically, by node number, or by location and apply the force using

F, all, x, 1

Force of 1N (or unit) applied in x-dir, to all selected nodes (check the syntax, I'm writing it from my memory).

In Ansys Workbench, I would make a "Construction Point" in DesignModeler or let the circle disc intersect with a line going through the center in order to force that there is feature (a point) in the center that I can select and apply my force to, when setting up loads in Workbench Mechanical. I dont know if you can put a force on a surface in Workbench Mechanical, and then define it to only apply the force at one location of the surface (therefore the above trick to first define that point in DesignModeler).

Good luck!

Christian Hansen
Twitter: @ChrHansen

FEA consulting made easy -

http://www.calcul8.it

 

[ViniciusV]

Thanks for the help.

Im using Ansys Workbench v13. I've tried to do that trick you suggested but it doesnt seem to work.

I can create the construction point in Desing Modeler at the center of the circle, but when I open the Mechanical I can't select it, actually it does not seem to be there.

I even tried to create a Named Selection in Desing Modeler with that point but even doing this the Named Selection does not appear in Mechanical.

Am I doing something wrong?

 

[Calcul8it]

If you also tried to let a line body go through and joint'ed them (I assume you put them in one part first) and still there's no center point, that you can use to apply your force, first, it sounds very surprising to me, and second, let's try it another way:
Cut the circle disc in four slices using the slice tool in DesignModeler (slice for instance by planes that you have defined perpendicular to the disc and centered to the circle) so you have essentially four slices - each its own body. Make sure all bodies are in one Part and then use either the Joint feature or Share topology. Now you have a circle disc with a cemter point you can use for your force.

Christian Hansen
Twitter: @ChrHansen

FEA consulting made easy -

http://www.calcul8.it

 

[ViniciusV]

Thanks for the reply.

I don't know if this change anything, but I didn't mention that the body was designed in another CAD program, actually it was Unigraphics NX, then I just imported it to ansys and oppened Design Modeler and tried to put that Construction Point.

Therefore when oppening the Design modeler I could draw the line but when saving/closing I couldn't see that line in Mechanical. What is suppose to happen?

 

[Calcul8it]

I guess you are then importing it in some standard geometry format (step, parasolid or iges) to DesignModeler. When you do so, make sure to mark it as "frozen" (in the import step) and keep your bodies in frozen (not "material") throughout your modeling - that's what I normally do (I'm working mostly with surface and line bodies).

For any problem in DesignModeler there are normally several ways to solve it. Though you could probably force a point in the center of the disc with a line body going through (or with a construction point), I would probably stick to the last option I mentioned, i.e. slice the disc, so that you get a cross in the center where you can apply the load.

If you can't make it work, maybe attach a screenshot of your model in DesignModeler and/or In Workbench Mechanical, so that I can see what's going on.

Christian Hansen
Twitter: @ChrHansen

FEA consulting made easy -

http://www.calcul8.it

 

[ViniciusV]

Thanks for the suggestion but I still seem not to succeed in selecting the construction point created in DM while using the Mechanical.

I've attached a picture of the model I'm trying to study, I'm modeling it in Unigraphics NX and I want to aplu the force in the center of the smallest circle, which is located left in the pic. Note that it is not any of the two roles in the model.

About the other suggestion of trying to slice the disc, I've tried to but I don't know how to do it.

 

[rcbsimoes]

if you were using apdl...
i would sugest:
1. creating a node at the position you want to aply the the force, 2. create a rigid region, or use coupled degrees
3. aply the force as calcul8t said.

in workbench.. i can't help you.
unless you use apdl macros in wb.
this is possible, right?!

greetings
rui

 

[ViniciusV]

Thanks Rui. Problably you can use APDL in Wb, but I really don't know how to use it. I started to use ansys after Wb and I've not mastered it yet.