Catenary vault simulation

Support Modeling
1

Hello,

As some may already know, Gaudi pioneered the use of catenary curves to optimize the vaults of his cathedral: he would use chains weightened with sandbags attached to the roof, and reported their curve upside-down on his plan. Here is what it looks like IRL: http://en.wikipedia.org/wiki/File:Maqueta_funicular.jpg

Now my questions is quite simple: is it possible to create a similar model in Blender ? Eg: draw a flat vault, attach different weights and launch a simulator, to see how it curves ?

Thank you for your help,

qwerkus

2

you would need to simulate the math equations for it

there was in 2.49 a Catenary curve but it was the unloaded type not the laoded one under tension!

now if you have an example showing how to solve these equations
cause i don’t have one example right now with me
i can see if i can make a small new script for this effect

by the way this requires an iterative process to determine the solution to a Transcendental_function / equations!

salutations

3

Hello,

Thank you for your reply. Wouldn’t it be enough to model a curve made of elements with different densities/weight, as described here: http://en.wikipedia.org/wiki/Catenary#Nonuniform_chains ?

Than I wonder if you would have to script it from the scratch. The soft-body panel already offers the possibility to simulate the effect of various weights attached to Vertices/Edges/Faces of a mesh. Would it be possible to adapt this function to show only the equilibrium point of the model, once gravity/weights are attached ?

Again, thank you for your time,

qwerkus

4

well it’s easy for one chain but if you want it for a vault ceiling
this represent a much more complicated set up
and might require a much more advance model using finite elements analysis!

unless you already found such a python program for a vault celing!

and BGE might be able to represent it in blender but it wont do the proper structural calculations

salutations

5

Thank your for your reply. I’ve been busy, and found this software online: http://designexplorer.net/newscreens/cadenarytool/cadenarytool.html
As it does the type of job I’m looking for, I contacted the author, which kindly offered me to share his libraries (java) to write a blender add-on. This way, all there is left to do is writing an interface to interact with the model: expected functionalities would be:
-create a catenary chain/surface in either mesh or curve mode (a snap option would be amazing)
-change weights on idividual knots
-an finally a ‘simulate-it’ button, which calculates the model.
I keep this thread updated, as soon as I get the libs.

qwerkus

ps: maybe this thread should be moved to the scripting subsection ?

6

but is it for a simple chain loaded catenary simulation
or for a vaulted ceiling which would be much more complicated ?

mind you if it is it would be interesting to have it in blender

let us know if you began working on a new script for this
that would be interesting

have you seen the script for a simple unloaded chain or rope in script section?

if you open a new thread let us know so we can follow it

thanks for feedback