self collision

[Jay Jay]

Hello,

  Does anyone know if Chrono supports self-collision detection for FEA (shell element)? For example, simulating cloth folding？

Regards,

Shuo

[Radu Serban]

Hi Shuo,

 

Yes, self-collisions are supported and enabled by default. See the documentation of ChContactSurface:: DisableSelfCollisions.

Unfortunately, I don’t think we have a demo that illustrates that.

 

--Radu

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[Jay Jay]

Hi Radu,

    Thanks a lot. I tested BST shell element. And I added the contact surface like this:

    auto cmat = chrono_types::make_shared<ChContactMaterialSMC>();
    cmat->SetYoungModulus(2e5f);
    cmat->SetFriction(0.3f);
    cmat->SetRestitution(0.1f);
    cmat->SetAdhesion(0);

    //
    auto contact_surf = chrono_types::make_shared<ChContactSurfaceMesh>(cmat);
    mesh->AddContactSurface(contact_surf);
    contact_surf->AddFacesFromBoundary(thickness/2.0);

   
    auto contact_cloud = chrono_types::make_shared<ChContactSurfaceNodeCloud>(cmat);
    mesh->AddContactSurface(contact_cloud);
    contact_cloud->AddAllNodes(thickness/2.0);

But the self-collision is not working. In my case, a rectangular strip composed of BST shell elements still experiences self-penetration, even with a very small time step size, and the issue persists.

Regards,

Jay

[I. Tiwari]

Hello Radu and Jay,

I was wondering if beam self-collision got working using the contactsurfacenodecloud method. I am trying to simulate a stretched filament colliding with itself. I have a a cosserat beam for this purpose and use the "ChContactSurfaceNodeCloud" implementation. I read from an old post on the forum that back in 2019, this was not implemented. I am not sure if it has been implemented as of now or not. 

Sorry for piggybacking on this post, and I wish you all a great day.

Best Regards,

Ishant

[Radu Serban]

Hi Ishant,

 

Mesh-mesh collisions (including self-collisions of an FEA mesh) would not work reliably with node cloud collision surface representations, as most collisions would be missed if the surface is only represented by collision spheres located at the FEA node locations.

You may be able to collide a mesh represented with a node cloud with a mesh represented with a mesh surface, but that obviously cannot apply to self-collisions.  You’ll need to switch the collision geometry representation of your FEA mesh.

 

--Radu

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