6 Replies Latest reply on Mar 6, 2016 9:10 AM by John Munroe

Assembly falling apart

John Munroe Mar 5, 2016 4:52 PM

Hello all

I have a rather simple assembly with just 5 parts. I'm trying to run a motion study in which a motor drives a slot wheel, but the whole assembly falls apart within one second into the simulation. Does anyone know why this might be happening? I've already tried the highest contact resolution, but it still falls apart.

Here's a short clip of it falling apart: Video

Any help appreciated.

Thanks

Motion Study.zip 434.4 KB

Re: Assembly falling apart

Wojciech Paterski Mar 6, 2016 7:37 AM (in response to John Munroe)

Just loaded it, there are not enough mates as far as I can tell. Not entirely sure what kind of move this should have.
But I'm guessing you are missing tangent mates between those pivoting balls and pivot ring and then concentric mates between pivot connector holes and rods from pivoting balls.
And i'm sure there's more mates needed. Doing some changes will post in a moment
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- Re: Assembly falling apart
  
  John Munroe Mar 6, 2016 7:40 AM (in response to Wojciech Paterski)
  
  Hi Wojciech,
  
  What it's supposed to do is, whilst the slot wheel rotates, the pistons also rotates around the brass ring.
  
  The pistons are already being pushed against the ring with springs; tangent mates aren't needed - right?
  
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  - Re: Assembly falling apart
    
    Wojciech Paterski Mar 6, 2016 7:45 AM (in response to John Munroe)
    
    they are needed otherwise your pivoting balls don't know where to stop, etc.. also looking at the cylinders connecting square base with ball and it looks strange:D
    
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    - Re: Assembly falling apart
      
      John Munroe Mar 6, 2016 4:40 PM (in response to Wojciech Paterski)
      
      I've made some changes incl. changing the length of the springs, but now the pistons protrude through the brass ring: Video
      I've already specified contacts and added tangent mates between the spheres and the ring. How come the pistons could protrude through the ring?
      
      Thanks
      
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  - Re: Assembly falling apart
    
    Wojciech Paterski Mar 6, 2016 8:11 AM (in response to John Munroe)
    
    I've done the assembly (corrected cylinder on one part) see zip file.
    But problem with motion is that you would want to use 'free' width and slot mates, and simulation doesn't allow those, but assembly I have if you do 'move component' and choose 'physical dynamics' i think it does what you want to do.
    
    motion.zip 528.7 KB
    
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    - Re: Assembly falling apart
      
      John Munroe Mar 6, 2016 9:10 AM (in response to Wojciech Paterski)
      
      Thanks. However, I keep getting mating errors. Could you please send it again?
      
      Thanks
      
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