Looking for Elastomeric Material Recommendation

[erwincm]

Hi guys. This is my first post and I'm not the sharpest tack in the box to begin with so please forgive me for my ignorance... That said:

I'm looking for an elastomeric material recommendation. The material should be suitable for injection molding or available in sheet form for die cut fabrication. I'm looking for something that will approximate a "constant force spring" when loaded in uniaxial tension. In other words, the material should facilitate stretching over a large range without a significant change in axial tension. The material should also demonstrate good shape recovery after repeated loading within a "reasonable" stress range.

Any suggestions you may have would be much appreciated!

Regards,
Charles Erwin

[Jorgen]

It is difficult to give strong recommendations without more information about your application. Perhaps a polyurethane would work in your application.

- Jorgen

[erwincm]

Please allow me to elaborate... We are presently die cutting small catanary parts from off-the-shelf silicone sheet stock. Here's a link to the PDF for our current concept: http://www.knology.net/~erwincm/Catenary.pdf

These parts are pretensioned to about 1.5lbf by stretching from 1.35in (untensioned state) to 2.25in. From there, we would like the catenary to stretch +/-0.5in with as as little change in tension as possible. In other words, we'd like the tension from 1.75in to 2.75in stretch to stay as close to 1.5lbf as possible.

We can change the catenary shape and material to meet these tension requirements. The current design is shown for reference only. Hopefully this will better explain our issue.

Thanks again for your help!

Charles

[Muzialis]

Charles,

there are some formulations based on filled NR which do show a plateau in an uniaxial strain stress curve in the region of 70 - 80% strain (quite close to your needs), just before a steep increase in stress due to strain crystallization.

They might suit your purposes, although probably you will have to re design your component to meet the strain reuqirements: unfortunately I can not help any more as the only I knew are proprietary blends. I am sure similar compounds are commercially available.

All the best

Muzialis

[erwincm]

Please forgive me for my ignorance but what does "NR" stand for? Do you know the names of any commercial developers of the proprietary blends? I don't even know where to start looking?

Thanks,
Charles

[Muzialis]

Charles,

my aopologies, NR stands for Natural Rubber.
I work for a company which develops its own compounds, so regretfully I can not be of any help on your second query.


All the best

Muzialis

[erwincm]

Could you provide me with a general web search term that might turn up some hits on proprietary material vendors??

[Muzialis]

Charles,

I would really like to help but I do not have a clue. Other than indecently trivial advices as searching for "rubber vendors" or " manufacturers" I would not really know, really sorry about that.

Kind Regards

Muzialis

[erwincm]

No worries. Thanks for helping.

Take Care,
Charles