Inventor 2018: Simulating a Self Aligning Bearing in Stress Analysis

[Anonymous]

Hi, I have a large drum supported by a trunnion at either end that uses self aligning bearings to handle the drum flexing up and down while it rotates. Is there a way to simulate the self aligning bearings in stress analysis? Previously when this was done in Autodesk Simulation Mechanical, a central node was created and connected via elements to the surface nodes of the trunnions, but I do not have access to that program anymore. I don't see a way to create nodes or any of that in stress analysis, and none of the components are frame members so it won't allow me to run a frame analysis. TIA

[JDMather]

Can you attach the assembly - or a simplified dummy assembly that illustrates the same desired behavior?

[Anonymous]

Not an assembly, but it gives you the idea and works the same. Basically when a load is applied to the drum, the drum would flex and the trunnions would normally tilt in the direction of the load, but the only way to constrain them that I see is as pins, which doesn't allow that angle change a self aligning bearing would give.

[Anonymous]

Anybody? I'm essentially trying to constrain around a central node like a ball joint.

[johnsonshiue]

Hi! I am sorry I have hard time visualizing the case. Is this about part or assembly? If it is about assembly, please attach all components (iam and ipt files).

Many thanks!

[Anonymous]

Part or assembly is not relevant. I need to constrain around a singular point. If there are normally six degrees of freedom (translation in x,y,z and rotation around x, y, z axis), I want to constrain a single point so there is no translation in x, y, or z, only rotation around the axes.

[kelly.young]

@Anonymous you can create a standard constraint from center point of the part to the center point of the assembly or another part feature/location/point.

Am I missing something?

Please select the Accept as Solution button if a post solves your issue or answers your question.

[andrewdroth]

You'll have to fudge it. Inventor's simulation is no where near as capable as Sim Mech.

I'd just add some geometry to act like the bearing pivot. Note that this limit's the slide in and out of the bearing which isn't accurate.

See Screencast. 

[Anonymous]

Do you understand that I'm trying to set one of the boundary conditions to perform an FEA analysis? Not assemble two components in an assembly file.

Or does anybody know if the NASTRAN In-CAD add on would give me this capability?

[andrewdroth]

Are you responding to my post?

[Anonymous]

@andrewdrothNo, sorry just saw yours, it was the guy above you. What you did is essentially what I've tried that works best, not as great as I would've liked though. I made a couple simple bearings with a pivot like that for each end. Stresses were just slightly higher than expected for the most part, except right next to the bearing surface. If there was a way to exclude Inventor from showing the stresses in certain parts, that would also be useful, but I don't know of a way to do that either (not exclude from the study, just not show me specifically those results).

[kelly.young]

@Anonymous yup I was missing the whole idea. 

[Anonymous · Accepted solution]

JUST FYI for anyone else who has this problem, NASTRAN In-CAD does solve this problem by giving you the ability to constrain each of the six degrees of freedom independently and allowing you to constrain around a single point.