Wire Rope: spring constant

[cnuk]

I need to find the spring constant (or load vs. deflection curve) for a piece of wire rope (1/4" 7x19 in my case). Surprisingly this is not something that any vendors publish....only breaking strength. I suppose the published data makes sense for the typical application where you are lifting/hauling/pulling on something and you don't care if the cable stretches 1/2" or 2". For my application however, I need to know this because it will affect the load other components see. I know K=AE/L but I don't think it is as simple as finding the cross sectional area of a cable (which is not published either).

Any Ideas?

Thank You

 

[IRstuff]

Have you looked at wire rope isolators? 1/4" sounds like it's in the ballpark of the larger ones:

http://www.enidine-europe.com/WireRopeIsolators.html#downloads

http://www.vmc-kdc.com/PDFs/wirearx.pdf

VMC either bought or inherited the Aeroflex line of rope isolators, but I know that they used to be able to supply you with force vs. deflection curves, at least, for the finished product. Nonetheless, I know that they have spent some amount of engineering to characterize and control the strand to strand slippage/friction.

TTFN

FAQ731-376

 

[KENAT]

I don't suppose experimentation is an option is it?

KENAT, probably the least qualified checker you'll ever meet...

 

[GregLocock]

google is your friend

eg

http://stinet.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA093040

Cheers

Greg Locock

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

 

[byrdj]

Similair question was asked in this post and good info there

http://www.eng-tips.com/viewthread.cfm?qid=191558&page=13

 

[ccw]

.
.
This is from an old Macwhyte Wire Rope Catalog G-18, 1981.
Page 169

e = [P/D**2]x F,
where
e = elastic stretch, percent of length
P = load on rope, lbs.
D = nominal rope or strand dia., inches
F = reciprocal AE factor x 100

Then from a table of "F" factors for your 7 x 19 construction:

Carbon: F = 1.40E-5
Stainless: F = 1.62E-5

"Answers are approximate, though should be accurate enough for the ordinary stretch determinations."