Stent - metal mesh cylinder design

[thurst]

Hey Guys,
I have read a few posts on here before and this is my first time posting. I am not that familiar with solidworks so I hope there is a simple answer.
What is the best way to design a stent in solidworks? I have attached a picture of one but you can find several just by googling "nitinol stent" or "metal stent".
I am struggling and I am hoping you guys can give me some good tips. Thanks
Tim

 

[CorBlimeyLimey]

The simplest way would be to create a tube, apply a mesh texture, and make the part transparent.

 

[thurst]

Would that also work for FEA modeling?

 

[CorBlimeyLimey]

I very much doubt it, unless you could change the material properties to compensate ... but my experience with FEA is listed below.

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[thurst]

Ha,
I need to design it and then apply the load from the FEA to see if my design can handle the necessary load...
I found another forum where somebody was trying to expand the stent:

http://www.eng-tips.com/viewthread.cfm?qid=235964&page=9

I just want to test the stent in the expanded state.

I also found someone using CATIA with the same question:

http://www.eng-tips.com/viewthread.cfm?qid=176225&page=44

 

[CorBlimeyLimey]

The only way I know to create the actual geometry would be to create a clockwise and counter clockwise helical sweep of the mesh-material profile, and then make a circular pattern of the result.

 

[zubaj]

I agree with CorBlimeyLimey, this is the way I've modeled parts like this in the past.

 

[thurst]

I am kind of a nube at SolidWorks also... so how do I create a helical sweep and a circular pattern. Also, there are more complicated designs that I may want to incorporate like the attached link. Can those be done with the same method?

 

[simoncarroll]

I'm pretty new to this and learning as I go but this is how I modelled a stent.
-Sketched a single repeating unit of the stent and performed a circular sweep to make a 3d part.
-Used a table pattern to plot where all the repeating units were in relation to each other to give me effectively a "2D" sheet of repeating units.
-Used the FLEX tool to wrap it into a tube shape.

Hope this helps.

 

[rstupplebeen]

If you are trying to perform FEA on this determine what assumptions you will make before creating the geometry.

Will you use beams, shells or solids?

How accurately do you need to model the intersections? Roughly what mesh size will you use and is that small enough to represent your details?

What loading will you be performing? You may be able to just model a single "X".

You might want to post this in your favorite FEA program's group.

I hope this helps.

Rob Stupplebeen

 

[NL8]

CBL,

Another option I've seen to a certain level of success, minus rebuild time, is to model the stent flat, cut the necessary diamond pattern into it, and bend it using sheet metal. with some tweaking you can get a rolled shell that almost connects and you can account for the gap in FEA by defining contact faces.

Joe Hasik, CSWP/SMTL
SW 09 x64, SP 4.0
Dell T3400
Intel Core2 Quad
Q6700 2.66 GHz
3.93 GB RAM
NVIDIA Quadro FX 4600

 

[NomLaser]

Have you tried the Fill command? This is typically used for fill patterns. You give the parameters such as spacing and size and it figures out the best pattern to fit your sheet or face.

 

[rstupplebeen]

thurst,

To help others with similar problems, what did you end up doing? Can you post your model or a picture of it with the design tree? Thanks.

Rob Stupplebeen

 

[krywarick6]

This might sound really dumb, but I been sounds that way a lot lately, but I have always taken the approach of modeling the way it is manufactured.

Is it wound like a spring and then welded? Is it expanded metal. Is it sintered?

This method should help to clarify the initial approach to the model. All of these answers are feasible, but remember, what will produce the best model for FEA.

Christopher Zona - Product Designer
Loretto, Ontario

 

[thurst]

I ended up using a less than ideal method that severely limited my ability to manipulate the mesh design. I made the argument in the project that this first design was preliminary and I was unsure of how the actual material would behave (I made some big assumptions about the material properties.)
I am not have SolidWorks anymore so I do not have a picture of the design tree handy but I can describe what I did.
I made a cylinder, then I hollowed it out. After that, I made a new plane on the side of the cylinder and I drew a diamond shape. Then I made a cut through one layer of the cylinder. Then I rotated the cut about the center axis and then I translated the cuts throughout the cylinder. Then I did a fillet on all cuts to make it look like the stent was made with fibers.
The material that I used was a bioresorbable polymer and the way they are manufactured is done on a big braiding apparatus. Microfibers are stranded together and the strands are then braided. After the stent is braided, the stent is partially sintered so the outside of each strand is solid and the inside is still like a fiber. This forms a nanocomposite.

 

[krywarick6]

That's cool.

Christopher Zona - Product Designer
Loretto, Ontario