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Solids interpenetrate at the start of simulation


AntoineSfx

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I have a tower of boxes, tightly on top of each others. At the start of the simulation, boxes start to interpenetrate slightly, then when another object hits it, it releases a a spring. What is happening and how can I fix it ?

 

tower.hipnc

Here you can see the problem to the bottom left. The tower eventually leans to it left and falls.

tower.PNG

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I poked around a bit and in the solver put Sleeping Time down to 0.1...looks OK...whether this is the right/proper way or not....I have no idea....

Another way, leave Sleeping Time as is, now since those blocks are simply boxes, I changed their Geo Rep to Boxes instead of Convex Hull....sorta works too...

Edited by Noobini
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16 hours ago, Noobini said:

I poked around a bit and in the solver put Sleeping Time down to 0.1...looks OK...whether this is the right/proper way or not....I have no idea....

Another way, leave Sleeping Time as is, now since those blocks are simply boxes, I changed their Geo Rep to Boxes instead of Convex Hull....sorta works too...

There are side effects when I decrease the sleeping time; objects freezing in the air for example. Not sure if it's the right solution, but in some cases the structure looks more stable.

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Sorry, not sure I understand the question. Usually interpenetrating geometry breaks sims. What is wrong is what you just showed. 

You don't know how to fix it? The pieces needs to be further from each other. Instead of using a copy node, use duplicate with a bbox expression, that way you'll get a perfect fit instead of eye balling it. 

https://i.imgur.com/wE7yRWM.gifv

Besides that you can go the packet geo inside dops and reduce the collision padding so it's more stable 

 

 

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7 hours ago, vtrvtr said:

Sorry, not sure I understand the question. Usually interpenetrating geometry breaks sims. What is wrong is what you just showed. 

You don't know how to fix it? The pieces needs to be further from each other. Instead of using a copy node, use duplicate with a bbox expression, that way you'll get a perfect fit instead of eye balling it. 

https://i.imgur.com/wE7yRWM.gifv

Besides that you can go the packet geo inside dops and reduce the collision padding so it's more stable 

 

 

Can you make a file with a simple stack of 50x1x50 boxes stacked on top of each others, that won't fall by itself ?

Even with boxes which are much more wide and deep than high, they fall like ice cubes in the wind.

When I do that, this fails like that:tower flat pieces.PNG

Also some pieces go right through the ground plane.

 

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