topic Re: Assembly joints not present in dynamic simulation in Inventor Forum

Assembly joints not present in dynamic simulation

3D4Play — Wed, 15 Dec 2021 03:42:24 GMT

I must be missing something somewhere, but when I create joints in my assembly, then enter the dynamic simulation environment, the joints I created don't seem to be recognized or available. I tried converting constraints to joints, but - of course - the joints are joints; they don't appear as constraints, and they also aren't available to select. Do I need to completely recreate those same joints in the simulation environment?

Re: Assembly joints not present in dynamic simulation

Gabriel_Watson — Wed, 15 Dec 2021 05:25:23 GMT

From the knowledge articles:

By default, when opening an assembly file, assembly constraints converts to standard joints between parts. Standard joints are not created if there are no assembly constraints between the parts or Automatically Convert Constraints to Standard Joints was disabled.
A non-flexible subassembly is treated as a single, rigid body. Parts are always rigid bodies. It is not possible to define mechanical joints between the parts of a subassembly that is not flexible.

https://knowledge.autodesk.com/support/inventor/learn-explore/caas/CloudHelp/cloudhelp/2021/ENU/Inventor-Help/files/GUID-91C22CA7-853E-440D-A752-B532A8E4CF37-htm.html

More on converting or having to enter joints manually here:
https://help.autodesk.com/view/INVNTOR/2019/ENU/?guid=GUID-58A2D813-E13A-417B-9B2E-6612A464B2A2

Re: Assembly joints not present in dynamic simulation

3D4Play — Wed, 15 Dec 2021 05:55:05 GMT

There's no useful information there. I want to be clear: I have a constrained assembly, which also includes specifically created joints at hinge points. I did this thinking that the joints (not constraints) would translate through seamlessly to the simulation environment. I did not select automatic conversion of constraints to joints by default, but - when I did convert them - I ended up with a bunch of grounded parts that defeated the purpose of the joints in the first place, and yielded the same net result: no joints, and no motion in the assembly.

To add clarity: I can effect motion in my assembly (by dragging specific parts in the assembly environment) exactly how I expect it to behave in simulation. It just that when I go into the simulation environment that I can neither drag components the same way, nor see the joints I had created in the assembly environment. I don't know if that adds clarity to my question or not....

Re: Assembly joints not present in dynamic simulation

JDMather — Wed, 15 Dec 2021 10:44:08 GMT

@3D4Play wrote:

… but - of course - the joints are joints;

Unfortunately I don’t think this is the case.

These were developed years apart and I don’t think there was any effort to make them correspond to each other.

I have (mostly) given up on assembly joints and use only assembly constraints for predictable conversion to Dynamic Simulation Joints.

Re: Assembly joints not present in dynamic simulation

3D4Play — Thu, 16 Dec 2021 07:33:53 GMT

That answer was pretty hard to swallow, so I put it up on a support case - just finished with the tech. The problem, to my amazement - is that Inventor does in fact see my joints...it just takes a solid 5-8 seconds before it responds in the simulator environment. Parsing that down further, I was really expecting Inventor to work a lot faster. It does not, and now I have to seriously consider a workstation upgrade to do these simulations, and other things, without waiting for what I believe to be an inordinately long amount of time. It wasn't all quite that simple - adding assembly constraints flakes joint settings that have to be reset., plus a few other anomalies.

Lesson learned!

Re: Assembly joints not present in dynamic simulation

JDMather — Thu, 16 Dec 2021 12:23:38 GMT

I suspect that you don’t understand Joints.

They we’re either there or not.

I doubt upgrade in hardware will have much of an impact on solver speed.

Can you Attach your assembly here?

Re: Assembly joints not present in dynamic simulation

3D4Play — Thu, 27 Jan 2022 21:01:34 GMT

Update: Development has assigned an INVEN to this.

To reiterate something mentioned above: I have a hard time accepting the supposition that there was never any intent for Assembly JOINTS to work in the dynamic simulation environment, where the application of JOINTS is a both a fundamental and an essential process. As it turns out, there is actually an intent for assembly joints to translate over to the simulation environment. Alas, it's another "great new feature" released with half-baked implementation. At least, I'm told this will be resolved in an upcoming release or update...fingers crossed for luck!