modelling inflatable structures

[lawmate]

Hi
I am trying to model a structure made up of inflatable reinforced balloon type cells. I would like to be able to simulate the cells being inflated and deflated to various pressures and if possible then test the effect of different forces on the structure. Does anyone have any reccomendation? The cell walls are made up of 6mm thick PVC. Does anyone have any experience of either modelling inflatbles or crumpling/folding fabric-liike material.
Any help greatly appreciated
Laurence

 

[GregLocock]

Whatever the answer is, Inventor is not it.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Jabberwocky]

Agreed, Inventor will not cooperate with this. Neither will any major parametric design program, unless you know precise measurements for each stage of inflation.

I would recommend something a bit more fluid like Maya or 3d Studio Max - there have some very powerful (if imprecise) surface tools that will let you at least mock up your structure. You could then (ideally) export that shape into an iges or stl and then perform FEA on it.

 

[lawmate]

Hi
thanks for the reply. i thought i might have to use something like 3ds max. I don't have any experience with it so was hoping there might be a technique in inventor, which i'm familiar with. Oh well, time for tutorials.
Cheers

 

[rollupswx]

i thought i might have to use something like 3ds max

Why 3ds Max? What exactly are you trying to do? 3ds Max is not an engineering software - it is a pretty picture visualization software.

I suspect your problem description doesn't accurately describe exactly what you want to accomplish.

 

[Jabberwocky]

Is Inventor truly more than a pretty picture visualization software? The end result is still usually just a 2d black and white print. Most of the modern 3d graphics programs can carry out operations to as many decimal points as you care to, they just aren't inherently geared towards precision. Their mates and constraints and 3d part relationships put CAD packages I've seen to shame though.

 

[lawmate]

What i am trying to do is design an inflatable structure made up of lots of individual cells. Imagine a bouncy castle, but a dome shape instead of a castle. The cells are akin to a layer of balloons stuck together and formed into a dome shape. It will be made up of a load of patterned pieces of pvc, welded together, like most inflatable structures.

I think i will model it first in 3ds max to get the overall shape of the structure, then use each polygon shape as a template for the individual pattern parts, which i can possibly assemble in inventor.

What i wanted to do is 1) build a model that tests the deflection of the whole structure when a simulated wind force is applied, and see how that deflection is effected by the pressures in the cells. 2) model different positions possible from inflating the cells to individually different pressures.

Sorry if you dont understand my description, but basically i wanted to know if there was a way in inventor to model inflatable systems that take their form from the difference in pressure between the inside and outside.
Maybe inventor isnt the best program for this but it is the one with which i have the most experience.

Thanks a lot for your help

 

[Spaceballster]

Seriously, why don't you try party balloons and cardboard/balsawood?

 

[retiredoldflattus]

Find out from NASA who designed those balloons they used on the Mars rovers and go from there. Really, the good old government is happy to help. Course it many take a zillion or so emails to find the info you need, but hey, gives you something to do At the very least you could find out what modeling program they used. Be sure to ask them what model of Cray supercomputer they used. I've used state universities many times to help me out. Generally speaking they love real world problems.