How to Preserve Initial Shape of a Flexible Body in MuJoCo Simulation?

Hi,

I'm a phd student and I'm trying to use MuJoCo for simulating a consignment with flexible packaging and rigid content.

I'm looking for some help with preserving the initial shape of a flexible body in my simulation.

My problem is that the flexible Packaging will not preserve its initial state and instead blows up like a balloon as shown in the attached picture. Is there a possibility to preserve the shape of the body until there is an outer force acting upon it, similar to how it's done in FEM?


Here is the XML for my issue:

The full XML, the Packaging.obj, and Content.stl are in the attached .zip file.

Thank you for your help!

[Consignment.zip](https://github.com/user-attachments/files/15924401/Consignment.zip)