folded plastic bags modeling

Dear All…

I am trying to model a 3000 x 2000 mm plastic bag using physics. What I am looking for is actually a plastic bag that falls down of a conveyor where it simulate the behavior of a bag folding over itself once it falls down to the ground.

Your quick feedback is highly appreciated;


Simulating deformable bodies and/or cloth-like objects is not supported at the moment. More specifically, the support for these seems to exist in the physics library, but it hasn’t been tested or integrated with the VC simulation (as far as I know).

Thank you for your informative feedback…

lease take a look at this simulation. Can it be done without the parts floating and get apart from each other. I used joint to attach the parts togetherbuset2.0.vcmx (2.7 MB)

Great start!

I’ve tried experimenting with different numbers and found that following parameters seem to work (the folding seems to happen and the parts don’t get apart that much):

  • For physics entities: mass density to 50-100 (or just setting mass directly), linear damping = 0.05, angular damping = 0.5
  • For joints: swing soft = True, swing spring = 10.0, swing damping = 1.0, projection linear = 1.0, projection angular = 10.0.

It may be possible to tune these even further. I’ve used following script to update all behaviors easily: (1.5 KB)

There are still issues which I was unable to understand or work around.

  1. The folded parts start on top, but in the middle of the lower conveyor they drop below. Within cloth simulation, there are other constraints that could solve this issue. As we don’t have those here, maybe generating additional joints between links 1-2 links apart from each other could help?
  2. When the parts are released at the end, they get pressed into the conveyor causing instabilities. Moving the P7 frame upwards seems to help. For example, when P7 and P3 are the same, the instabilities are minimal. Not sure how to fix this properly though…

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Thanks a lot Yanto for your help. I will try to find the optimal values and maybe increase the number of joints. Lets see the final results.

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