Dynamic Simulation Overconstrain

[vkulikajevas]

I have been trying to get this Assembly work, desperately re-mating, rejoining, reassembling all the parts. And Inventor seems to be having really difficult time to understand what I want from it. Can someone help me to solve this assembly?

It is a bridge system, when one side of bridge is pressed another is symmetrically affected by the joints. 

In the end, there are too many Overconstraints and DOM's (even if i am able to get 1 DOM, Inventor shows ~10 overconstraints..). Although I only make the moving part mates. Can you please check if I am making the right joints and mates?

[JDMather]

What version of Inventor are you using?

iProperties would seem to indicate very old 2017 without any Service Packs installed.

How much prior experience do you have with eliminating redundancies on prior projects, or is this the first time?

It will be difficult to communicate as you are using older release, but most common remedy is Spherical and Point-Line Joints in place of Revolution or Cylindrical Joints.  Sometimes Point-Plane.

I might be able to communicate the basic issue with a single part as the discussion progresses.

[vkulikajevas]

@JDMather thank you for your reply. I don't believe it has anything to do with version. It worked before, just got too complicated with more complicated joints I introduced to the assembly. I would really appreciate if you could take a look through the mates I used to assemble the moving joint, and give tips on that.

I am sure this thread would be very useful to others, as there is not that many information about Dynamic simulation in Inventor. 

[JDMather]

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@vkulikajevas wrote:

I don't believe it has anything to do with version.

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The problem is that you would not be able to open my files to analyze the solution.

The alternative would be for me to write a book.  Wasim Younis already wrote a book.

But again, the issue would accessing 2017 version example files.

[vkulikajevas]

@JDMather  I don't mind if you could solve this in higher version of Inventor.

I would use similar methods in 2017. If it didn't work, then we would know for sure that it is an issue in Inventor version support.

[JDMather]

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@vkulikajevas wrote:

@JDMather  I don't mind if you could solve this in higher version of Inventor.

I already know what the issue is and how to solve it.

I know how to solve it in 2020.

I knew how to solve it in 2017.

I knew how to solve it in 2010.

The issue is the same in any release and in SolidWorks or any other MCAD software.

The problem is that I do not have 2017 so that you could see the solution and it would take too many words for me to explain the solution.  I could make a video, but that would take me several hours of work to create the video (I do not like to post anything below at least a minimum level of quality that is associated with my name.)

So the solution is the same in 2017 as it is in 2020 and was in 2010, but I don't have time.    Replace strategic Revolution and/or Cylindrical Joints with Spherical and Point-Line Joints to remove over constrained redundancies.

This is covered in the Wasim Younis book.

Do you own the Wasim Younis book on Dynamic Simulation?

[vkulikajevas]

I was able to solve the hinged problem. But the joint mechanism with a prismatic joint at the center is a difficult task.
Prismatic joint takes 5 degrees of freedom, and leaves only 1, and there are 2 joints connecting to it, both of them requiring at least 3 degrees of freedom, which makes this problem a mind blow.
Someone have any suggestions? 

[j.palmeL29YX]

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@vkulikajevas wrote:

I was able to solve the hinged problem. But the joint mechanism with a prismatic joint at the center is a difficult task.
 

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Post what you have now (your current version).
(And, please, don't include all the unnecessary folders as Design Data, Libraries, Old Versions, Templates in the zip-file).

[vkulikajevas · Accepted solution]

@JDMather  thank you for your answer. I have managed to solve the mechanism.

although the model works, when applying Jack force calculations, Inventor always crashes. (Doesn't crash on the simplified model)

Simplified model is always a best decision in Dynamic simulations. Smoother operation of model and much easier recognition of mates for program and user. (I have also noticed that the Inventor is less likely to crash if there are as minimum complicated geometry as possible in Dynamic Simulation)

Always best is to simplify the model as much as possible

@JDMather  using hinges with Sphere and Point-line joint helped too, although, I don't really understand the use of that. It just separates the forces across two hinges (or one), but somehow using one rotational joint makes more sense. And if you need the force distribution, you can count theoretically by dividing Rotational joint force by the number of hinges, probably? In terms of redundancy I understand why you can't use 2 hinges with rotational Joint on one moving bridge, because it create additional redundant over constraints. But what if you want to see all the forces, represented exactly on all the hinges. I am sure there is a bit of difference between them always, especially if the door or the bridge is not  symmetrical to perpendicular plane between two hinges...