topic Re: Dynamic Simulation - Redundant joints and other questions in Inventor Forum

Dynamic Simulation - Redundant joints and other questions

karthur1 — Thu, 17 Feb 2022 17:31:05 GMT

Trying to get a simulation to work with my mechanism. Can't make any progress clearing them. I have the "Automatically Convert Constrains to Standard Joints" checked. I have built most of the assembly using joints rather than constraints. It works great when I move it in the assembly environment, but when I go to Dyn Sim, I get these redundant joints.

Another question is why is this one item in my browser shown in BOLD? Even when I go back to the assembly environment, it is still bold.

I don't do these dyn Sim very often, so any tips are appreciated.

Re: Dynamic Simulation - Redundant joints and other questions

j.palmeL29YX — Thu, 17 Feb 2022 18:34:44 GMT

Without seeing your model it is almost impossible to give helpful answers. Post your files (.iam, .ipt) please. And tell us which Inventor version you use.

BTW: The Help (F1) says: Bold letters identify parts linked to selected objects.

Re: Dynamic Simulation - Redundant joints and other questions

karthur1 — Thu, 17 Feb 2022 19:05:51 GMT

There is nothing selected and its still bold. Let me get the files together.

Re: Dynamic Simulation - Redundant joints and other questions

karthur1 — Thu, 17 Feb 2022 19:37:58 GMT

@j.palmeL29YX

See Attached for the files. See the F3635-D828_V2 Dyn Simulation.iam file. My files were done in Inv 2020.

Re: Dynamic Simulation - Redundant joints and other questions

JDMather — Thu, 17 Feb 2022 20:16:22 GMT

I have only just started looking at the assembly - but you should not have spring parts in the Dynamic Simulation. Instead use Spring Joints.

Minor point - I found an interference here...

Re: Dynamic Simulation - Redundant joints and other questions

karthur1 — Thu, 17 Feb 2022 20:18:06 GMT

There is a "Stress Analysis" LOD that suppresses those springs.

I found another example where you helped someone else that was having redundant issues as well. I am just starting to look at the way you got it to work, but I think the solution to my issue might be similar.

Thanks

Re: Dynamic Simulation - Redundant joints and other questions

karthur1 — Thu, 17 Feb 2022 21:33:17 GMT

@JDMather

I got the joints so there are no more redundancies, but when I try to drag, I get "Impossible to proceed with the simulation. Check the input data."

I attached the iam below. It uses the same parts as my previous iam.

Re: Dynamic Simulation - Redundant joints and other questions

j.palmeL29YX — Fri, 18 Feb 2022 06:41:07 GMT

First I checked your first posted assembly (<<Click<<).

A lot of interferences (see attached image), a lot of redundancies - but the simulation >>works well<<.

Then I found your second upload (>>Click<<). Still some interferences, also o redundant joint - but the simulation >>works well too<<.

I do not yet see how I could help you.

Only some tips (my opinion):

- First remove all modelling errors (interferences)

- Then I'd add each joint (in the DS) manually step by step. Check each joint step by step if it works as you expect.

- At least one joint should be a "driving" joint (or do you really want the gravity as driving force?).

I do not know what you expect how the mechanism should work (at the moment it moves in a not realistic manner). If you can explain what's your goal I can perhaps give you more help.

For a rough test I added a spring and also two vertical forces - see the >>simulation<< result. Obviously it works well.

Re: Dynamic Simulation - Redundant joints and other questions

j.palmeL29YX — Fri, 18 Feb 2022 08:21:27 GMT

Here still another test: I open your (second posted) assembly. I do not change anything on the assembly. Go to Dyn. Simulation and can drag the mechanism >>without of problems<<. I can't reproduce what you're reclaiming about.

Re: Dynamic Simulation - Redundant joints and other questions

JDMather — Fri, 18 Feb 2022 13:04:22 GMT

@karthur1 wrote:

I attached the iam below.

You have wayyyy too many top-level assembly constraints. Demote components into sub-assemblies that move together. This will dramatically reduce the number of DS Joints.

I started to do this to illustrate and then as @j.palmeL29YX pointed out - I got to thinking, "What is your intent?"

If you are going to run Motion Loads Analysis (FEA) on any of the parts - I need to leave those parts at the top level rather than demoting to one of the sub-assemblies.

Please advise before I continue work.

Re: Dynamic Simulation - Redundant joints and other questions

karthur1 — Fri, 18 Feb 2022 14:49:21 GMT

@JDMather

Can I send you a private email?

Thanks

Re: Dynamic Simulation - Redundant joints and other questions

TheCADWhisperer — Fri, 18 Feb 2022 17:13:06 GMT

TheCADWhisperatgmaildotcom