Hello,
I’m trying to model a membrane with a surface load to form-find a concrete shell, based on the example file for 5pt sail. When I add the SrfLoad, I get an error in DefMod stating:
membraneSrfLoad.gh (28.8 KB)
I did try changing Load values, disabling cables, and changing material, but keep getting it.
Am I doing something completely (or partially) stupid?
Thanks in advance, Eduardo
Hey,
form finding with loads is a bit tricky. If the load is too large, it cannot find equilibrium as the given prestress (here the cables) are not able to balance the load. In the formfinding analysis, cables can elongate without evolving stresses; they only have the prestress as inner force. However, your model works if you set the load to a really small value. I tried 0.013.
A hanging model would be another, more robust approach to your design target. You can directly use a shell model. You can reduce the bending stiffness by reducing the thickness by a factor and multiply the Young’s modulus by the same factor. By that, you have the same inplane stiffness but less bending stiffness and it will deform according to the hanging shape. You can also run some iterations. (It is briefly described here: Frontiers | CAD-Integrated Parametric Lightweight Design With Isogeometric B-Rep Analysis | Built Environment)
Thanks Anna for the prompt reply (as always!)
The small value for load is working well for the membrane, though I’ll probably test the shell solution you suggested.
Bis gleich!