Hertz Contact Patch and Curvature Information in Chrono

[OUSSAMA EL MOUIAH]

Hello Chrono developers,

I am currently  investigating the use of Hertzian contact within Chrono (SMC).

I have a few questions regarding the contact information available through Chrono:

1. As far as I understand, the Hertz-based contact models implemented in ChSystemSMC provide the normal contact force using the penetration depth and equivalent radius, but they do not provide the actual contact patch dimensions (e.g., semi-axes (a) and (b) of the Hertz ellipse) or the contact area directly. Is this correct, or is there already a way to access this information?

2. In my tests, the collision systems based on Bullet and Multicore seem to provide contact points and normals, but not the principal curvatures (or curvature radii) of the contacting surfaces for arbitrary geometries. From the source code, it appears that Multicore computes equivalent radii only for some primitive shapes (sphere, cylinder, box, etc.), while for general triangle meshes or custom geometries this information is not available.

   Is there any existing module, utility, or ongoing development effort within Chrono aimed at computing local surface curvatures (principal curvature radii) at contact points for arbitrary collision geometries?

Any guidance or suggestions would be greatly appreciated.

Thank you.