Issues driving cycloidal drive reduction assembly

[slaglebot]

Hi all,
I've been attempting to design a cycloidal drive reduction in Inventor 2022. However, I have been running into issues driving the finished assembly. Whenever I constrain the assembly to the surface of the wobble disc in any way, driving it refuses to work. It seems only a limited number of states are possible - the assembly does not want to interpolate between them. Some examples are a) adding relevant parts to the Contact Solver or b) adding surface tangent constraints for the wobble disc and the outer set of bearings.
This also prevents me from using any simulation feature - when creating a dynamic assembly, Inventor tells me that the simulation is impossible.

The assembly (packed) is attached.

[swalton]

I'm using Inventor 2024 but it should work with 2022...

Try a Transitional Constraint between a NeedleRollerBearing.ipt and the CycloidalDiscPart. 

If I use a single Transitional Constraint, I can drag the EccentricCamPart and the CycloidalDiscPart hunts a bit.

If I use two Transitional Constraints with different NeedleRollerBearing parts, I can get smooth motion.

If I use 7 or more, then my computer has trouble keeping up with my drag motion.  Two Transitional constraints seems to give the correct motion. 

What are you trying to learn from Dynamic Sim?  Will simplifying the problem down to two NeedleRollerBearing parts give you useful info?

[slaglebot]

I'm trying to analyse the forces applied to each of the parts over time - chiefly, the CycloidalDiscPart - to assist with material selection. I was unsure if the part would be able to handle operation if made out of acetal. The idea would have been to apply the peak force observed here to the part in an FEA study.

Thank you for being patient with my response.

[kacper.suchomski]

Hi

This is what a dynamic simulation environment is for.

[JDMather]

@slaglebot 

It appears to me that you designed using "perfect" geometry. I do not see logical clearance between Components.

In the real world we cannot manufacture perfect parts.

Once you have added realistic clearances I would use 2D Contact Joints in Dynamic Simulation.

Edit: Oops, just remembered that Contact Joints cannot be used for Motion Loads Analysis.

That makes this all more difficult...

Run the simulation and then Export Motion Loads to FEA at critical Time Steps in the simulation.

If you have some idea of where/when the critical loads occur - you don't have to model the entire assembly of needle roller bearings.  The roller bearings can be simplified (actually all that is needed is a single sketch circle) and can be grounded (I assume you are testing the CycloidalDiscPart.)

Idealize the assembly for ease of calculations.

And I recommend that you install the Updates for your version of Inventor...

There are at least 3 Updates.