RE: [chrono] self collision

Wed, 14 May 2025 07:14:35 -0700 

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

From: [email protected] <[email protected]> On Behalf 
Of I. Tiwari
Sent: Wednesday, May 7, 2025 9:39 PM
To: ProjectChrono <[email protected]>
Subject: Re: [chrono] self collision

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
On Monday, January 20, 2025 at 7:38:18 AM UTC-5 
[email protected]<mailto:[email protected]> wrote:
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

在2024年12月24日星期二 UTC 11:29:31<Radu Serban> 写道：
Hi Shuo,

Yes, self-collisions are supported and enabled by default. See the 
documentation of ChContactSurface:: 
DisableSelfCollisions<https://urldefense.com/v3/__https:/github.com/projectchrono/chrono/blob/3c8778609d7569c39bcd71a5ebc92c7785c1f09b/src/chrono/fea/ChContactSurface.h*L52__;Iw!!Mak6IKo!K5WZzLsWIesLYa4LaubbPhS5uM3d6GxzJTAFqW1SkHrNUmE90P5n3TEF-IeNTAhAur3NYgLS4lehFtNSXVsVl_s$>.
Unfortunately, I don’t think we have a demo that illustrates that.

--Radu

From: [email protected]<mailto:[email protected]> 
<[email protected]<mailto:[email protected]>> On Behalf Of 
Jay Jay
Sent: Tuesday, December 17, 2024 12:21 PM
To: ProjectChrono 
<[email protected]<mailto:[email protected]>>
Subject: [chrono] self collision

Hello,

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

Regards,
Shuo
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