Rigid body modes in the system - Karamba 3D


I’m currently working on optimizing a tensegrity tower within Grasshopper using the Galapagos tool. My objective is to consider both the structural stability and material consumption in the design process. However, I’ve encountered an error during the analysis of my tensegrity tower in Grasshopper. The error message I’m receiving states: “There are 5 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.”

As a result of this error, I’m getting significantly higher deflections in my results, which I suspect may be related to this issue. I would greatly appreciate any assistance or guidance from anyone who can help resolve this problem. Here, I have attached some images and the model for your reference. Thank you in advance.

tower.gh (126.8 KB)

did you use the eigenmodes component to check where the model might be instabile yet?

No. I don’t have any proper idea about how it works. Can you please help me with that?

I’ve used the Eigen Modes component, but upon activation, it displays an unexpected structure that doesn’t align with the intended geometry. Additionally, I’ve confirmed that no multiple points are coinciding in my model, and I’ve used ‘Node tags’ in ModelView/Structure Tags to make sure that there are no overlapping nodes. I would appreciate your assistance in resolving this issue. Thank you.