Antoine, Have you ensured that the collision meshes are flagged as concave in the ChCollisionShapeTriangleMesh<https://api.projectchrono.org/classchrono_1_1_ch_collision_shape_triangle_mesh.html> constructor (4th argument set to false) and provided a non-zero mesh thickness (5th argument, which defaults to zero)? Please take a look at how collision meshes are set up in demo_MBS_collision_trimesh<https://github.com/projectchrono/chrono/blob/main/src/demos/mbs/demo_MBS_collision_trimesh.cpp>.
--Radu From: 'Antoine Laborde' via ProjectChrono <[email protected]> Sent: Wednesday, October 1, 2025 2:12 PM To: ProjectChrono <[email protected]> Subject: [chrono] Contact detection on mesh objects Dear all, I work on watch parts simulation through rigid body dynamics. I had problems with contact detection between some parts so I decided to build the simplest scenario where I get the problem. This scenario is the simulation of gears (as mesh objects). The problem is that the teethes of the gears don't collide, they go through each others. The script does the following: - load the STL files of the gears - create ChBody for each gear - add triangle mesh visualization shape - add collision shape using ChCollisionShapeTriangleMesh - apply a torque to one of the gears using AccumulateTorque() until a speed of 0.05 rad/s is reached I am using ChSystemNSC with BULLET collision detection. I checked project chrono documentation page on collision detection and tuned the contact envelope and margin but didn't get any result. To make sure it was not due to the accuracy, I reduced the speed of the gear and set the time step to 0.001 s. When I launch one gear on the other, like throwing a ball on another, the collision occurs. I don't have a lot of experience on rigid body analysis so any feedback would be greatly appreciated ! Best, Antoine -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To view this discussion visit https://groups.google.com/d/msgid/projectchrono/013ce180-1ec7-4d6a-95c1-e6e91e3c81f2n%40googlegroups.com<https://urldefense.com/v3/__https:/groups.google.com/d/msgid/projectchrono/013ce180-1ec7-4d6a-95c1-e6e91e3c81f2n*40googlegroups.com?utm_medium=email&utm_source=footer__;JQ!!Mak6IKo!KIcttF-aY_trjz5PerxrXWX2bImARUwfANsEX8FfnOwUFoQ-ke9wZgFmNIKcO100oIy6jvCjFsJEaX974-UFEpQcvuI$>. -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/projectchrono/CH3PPF46CDC21855DC40BBD86BF75AF6671A7E4A%40CH3PPF46CDC2185.namprd06.prod.outlook.com.
