Tensegrity Force Analysis

Grasshopper Karamba3D
1

Hey,

I am trying to analyse the forces acting in a tensegrity structure, and cant quiet seem to get it to work.
It is a system of struts and cables that is self supporting, and I am wanting to look at the internal forces when it is under compression.

I have modeled all the struts and cables so that the cables are essentially struts with buckling and bending turned off, and the struts have no bending stiffness as well.

There are two main issues im having:

1 - When I fix one base support and have another semi fixed, the structure does not deflect correctly, and analysis doesnt have a converging displacement.

2 - When I remove the semi fixed support, the structure displaces correctly , but still doesnt have a converging displacement.

What makes this weirder is that when I incrementally increase the load, it seems to be deflecting correctly, but at no point does the analysis converge.

Can somebody please help?

Thanks!
James
Tensegrity_Anlaysis_Model.gh (44.9 KB)
Base%20Model

Correct%20Displacement%20Displacement
Correct Displacement Displacement.JPG343×684 35 KB
Incorrect%20Displacement
Incorrect Displacement.JPG398×677 38.9 KB

2

Dear James,
you structure is kinematic. This is probably the reason why the calculation does not converge (see attached definition: Tensegrity_Anlaysis_Model_cp.gh (47.5 KB) ).
Best,
Clemens

1 Like
3

Hi Clemens,

Thanks for getting back to me.

Does this mean that I will be unable to analyse the structure the way I want in its current state?
If so, can you make any recommendations as to how I can correct this?

Thanks,
James

4

Hi James,
in its current state your model can move without deforming.
You can change the gometry (for example break the symmetry) or add members to prohibit that.
Best,
Clemens