Modelling a rope in Solidworks 2006/ 2007

[dudeSW]

I am trying to model a braided rope in Solidworks. Can anyone advise me on how to do this. I have tried many things and have been unsuccesful. If anyone has any suggestions please let me know.

Thank you!!

 

[drawoh]

dudeSW,

Is the rope straight, or does it hang between its ends. A straight rope would be a couple of helices, with the circle sections overlapping a bit.

I heard somewhere that ropes and chains hang in a hyperbolic cosine. Modeling this with helices will be fun!

JHG

 

[Timelord]

Just how accurate do you need to model it? A sweep with twist of the rope cross section along a 3D sketch should give you excellent visual results. Making it move like a rope in an animation will be more problematic, but there are a lot of experts here who can help you with that.

Timelord

 

[dudeSW]

Thank you drawoh and timelord for your responses. I think I did not explain myself well. I need to model more of a braid. So the individual strands have to interweave. I am having trouble with the weave. Please suggest if you can. Thank you again!!!

 

[dudeSW]

Also, I need to model it accurately as I would like to preform an FEA analysis on the model in compression.

 

[ctopher]

In SW 2007 you can also use the Flex command.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Jul 13, 2008)
ctopher's blog

 

[dudeSW]

ctopher,

can you explain how i can create a weave with multiple strands with the flex command? This was one of my attemps earlier that was unsuccessful. I also tried projecting a profile on a curved surface. Is there a way to how a helix follow a guided curve? Would this work?

Thank you!

 

[drawoh]

dudeSW,

You are going to have to search a manual or the internet for whatever rope braid you are using. Perhaps a boy scout manual or an outdoor survival book will tell you something. There are many ways to braid ropes.

There are ways to fake geometry like this, but not if you are doing FEA.

JHG

 

[MadMango]

Compression?

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[ctopher]

Create a sketch with the strands where you want them, then extrude it to the required distance...plus a little more.
Use the flex command to twist the extrusion as needed, then add bends via the flex command.
I have created braided wire like this. It takes a little practice, but works.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Jul 13, 2008)
ctopher's blog

 

[ctopher]

Here is an example of the flex command (attached).

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Jul 13, 2008)
ctopher's blog

 

[dudeSW]

Thank you for the example. The rope, (braid) i need to make is somewhate more complex. I need the strands to weave together like a basket. The basic way to think about it is like the braid in someone's hair. The model will be a basket like weave with no bottom to the basket.

 

[ctopher]

Can be done with pratice. Or as the other's suggested, a 3D sketch with a sweep. YouTube may have some examples.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Jul 13, 2008)
ctopher's blog

 

[DraftingMan]

dudeSW,

Is this more like what you are trying to model?

If so, I am not sure SW can do this without a lot of work.

John H. Dunten, CD
Certified Drafter

 

[WhitneyPaine]

Modelling it will be a pain.

You mention FEA. If this is the primary aim, could a bit of lateral thinking create a really simple model to test. i.e. multiply up the strands?

I must confess I know as much about FEA as the first chapter of the Cosmos Works Designer manual, so this might be completely rubbish advice.

Regards

WP

http://www.whitney-paine.com

 

[drawoh]

Compression?

MadMango,

That occurred to me too. I figure you can push a rope if it is short enough, but maybe then you should not consider it a rope. See thread1103-224665 for what happens when a semantics discussion gets out of control.

I do not see how any analysis is going to work here without a precisely accurate model of the braid. No handy dandy visual trick is going to work here.

Is this a metal or plastic rope, or is it a rope made of some grossly non-homogenous material like what ropes are traditionally made of?

JHG

 

[dudeSW]

DraftingMan ,

That is exactly what I am trying to model!!

Any suggestions anyone?

Thank you!

 

[ctopher]

I wouldn't bother modeling it. It would be a headache, take a lot of your time to figure it out, then model it. FEA will take longer and possibly crash.
I would create a basic model close to it, then apply appropriate materials to it.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Jul 13, 2008)
ctopher's blog

 

[dudeSW]

Sorry, I used rope for lack of another term. Semantics, an impartant factor in communication.

You are correct that an analysis won't work without a precisely accurate model. This is why I am inquiring about methods to develop a model.

The material is metal, I have all the values I need in order to run an analysis, i just need to develop the model.

 

[ctopher]

If it's a cable or wiring, or ?? ... model it, then model a 'shell' over it. Add the correct metal to the 'shell'.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Jul 13, 2008)
ctopher's blog