Why does a concrete‑like object exhibit unexpected behavior in Blender rigid body simulations?

This answer is a conservative draft because the supplied sources do not contain Blender‑specific information. The steps below reflect common practice and should be reviewed and tested by a knowledgeable user before being applied to a production scene.

1. Check scene scale – Ensure the model’s dimensions match real‑world units (e.g., 1 Blender unit = 1 meter). In the Scene Properties panel set Units to Metric and Scale to 0.01 if the model was created in centimeters. Verify that objects are not excessively large or tiny, as extreme scales can destabilize the rigid‑body solver.
2. Select collision shape – For concrete‑like objects start with a Convex Hull collision shape; it provides a good balance between accuracy and solver stability. If the object has concave features that are essential, use a Compound shape built from multiple convex hulls or, as a last resort, a Mesh shape (which is more expensive and prone to instability).
3. Adjust solver settings – In the Rigid Body World settings increase Solver Iterations (e.g., to 20) and enable Deactivated Start if the object should begin static. Increase the Substeps per frame (e.g., to 8) to improve stability for high‑detail meshes.
4. Mesh cleanup when detailed mesh fails but proxy works
   • Remove non‑manifold edges: Select → Select All by Trait → Non‑Manifold and delete or fill.
   • Eliminate intersecting geometry: use Mesh → Clean Up → Delete Loose and Merge by Distance with a small threshold (e.g., 0.0001 m).
   • Apply all transforms (Ctrl + A → All Transforms) to ensure scale, rotation, and translation are clean.
   • Consider decimating the mesh or using a low‑poly proxy for collision while retaining the high‑poly mesh for rendering (enable Proxy or Collision modifiers accordingly).
5. Verification – Play the animation and watch for interpenetration or jitter. If problems persist, revert to the proxy collision shape, confirm stability, then gradually re‑introduce detail.
6. Rollback – Keep a copy of the original object (e.g., hide it in a separate layer) before making changes. If the simulation becomes unstable, delete the modified object and restore the backup.