Hello.I’m trying to make truss on grasshopper using karamba. When I plug it Assemble component says that “1. There are 96 rigid body modes in the system. This means some parts can move freely without causing deformation.
Try to use the ‘Eigen Modes’-component and activate the display of local coordinate axes: The first eigen-mode will be the rigid body motion.
If this does not help, check whether you have a pinned support directly attached to a hinge. A hinge introduces an extra node which may cause the problem.
When analyzing a flat shell structure one has to lock the rotation perpendicular to the plate in at least one node.”
I already checked support and hinge, but still not working.
Thanks in advance and I’m sorry for my bad English.
Hello Wallpillar,
the joint definitions in you definition allow for many rigid body modes. If you e.g. define a rx-hinge on both sides of a beam, the beam is free to rotate about its own axis.
Hinges are like zero length spring elements which connect the end of a beam with the corresponding node. If the node itself is kinematic this does not show up in Karamba3D 1.3.2.
The attached definition still shows some out of plane kinematic modes.
Best,
Clemenskaramba_test_2_cp.gh (40.0 KB)
Thanks replying , Clemens.
I would like to release Ry moment about B and C Element, because I don’t want Y direction moments on B and C Elem.
I just try it now, but It’s didn’t work. How do I release Ry moment on both node of the beam in this model? Thanks.
