[Bug] Contact Starts Overlapping error

[SuvrangshuBarua]

Summary

I have previously simulated folding of an airbag as shell object on a former version of the solver and Blender Addon 1.0.12. However, I tried to reproduce the same simulation on the latest release but the simulation freezes at frame no 30 and eventually stops. The given error is "contact starts overlapping: two surfaces begin the step already touching or overlapping (a contact pair is inside the contact offset at the start of the step)".

Here is a drive link to the zipped .blend file.

Steps to Reproduce

1. Assign the planes under "Bottom" and "Top" collections as Static object group
2. Assign "folder-PRC" as Shell object.
3. Transfer and Run.

Expected Behavior

The folding simulation was expected to run completely.

Actual Behavior

The simulation freezes and eventually stops with error.

Environment

RTX 4070 laptop GPU
Windows 11
Blender 5.1.2

Contribution Agreement

• I confirm that any code, patches, scripts, attachments, or other copyrightable material I include in this issue may be used, reproduced, modified, and distributed by this project under the Apache License 2.0 or as otherwise described in CONTRIBUTING.md.
• This is a bug report from the community (please provide a reference below).

Community Reference

No response

[ryichando]

Okay taking a look soon. Marked queued.

[SuvrangshuBarua]

@ryichando, just for your reference, here is a video of the folding simulation I created using the previous version of the solver that I mentioned.

blender_Hx8QmrcHgb.mp4

[ryichando]

Thanks! Aside from the bug this simulation already looks pretty!

[ryichando]

Hi! I reviewed your file and noticed that the back panel passes through the front panel during the animation. See the video:

backside-front-60.mp4

There's no way the pinned sheet can avoid penetration between these two panels. In this case, the simulation should correctly crash. If it doesn't crash, it would actually violate our non-penetration guarantee.