Elastic modulus of wire rope 2

[pontiacjack]

This question is automotive-related only because I'm working on a trailer that will haul a race car.

I don't have an M.E. degree and I couldn't find the answer in Machinery's Handbook.

I need a ballpark value of modulus of elasticity (in tension, of course!) of a cable of 1/2" diameter, 6 x 19, galvanized finish. Assume the material is a "good" steel alloy with a nominal modulus of 30 x 10^6 PSI.

Thanks.

 

[swall]

You might want to repost this on one of the civil engineering forums.

 

[patprimmer]

It will depend a lot on the lay up and twist.

I presume the 6 19 is number of yarns and number of strands per yarn.

I can't answer your question, but I would think whoever does, needs the twist data.

Regards
Pat
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[btrueblood]

You need to contact the mfgr of the wire rope, and ask for typical data. The data will not be very reproducible from batch to batch of rope. The stretch-vs.-tension curve will also not be repeatable unless you first stretch to a maximum expected load, then unload and repeat (due to movement of the individual wires as the rope is loaded, there is a lot of hysteresis in the rope stretch curves). If the wire is wound onto a winch drum it will similarly change its stretch vs. tension curve further (but by much smaller amounts if the winch drum was properly sized) with each wind/unwind cycle.

 

[IRstuff]

Kind of begs the question of where in the middle of "hauling a race car" is this rope being applied, since most hauling applications use trailer hitches to make the connection.

There ought not be any self-created structure that's being loaded under use. That's just asking for lawsuits if it ever breaks.

TTFN

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[BrianE22]

My old MacWhyte Handbook has some numbers (see enclosed).

 

[MiketheEngineer]

For example:

My book shows:

3/8' 6 x 19 FC IPS has a breaking strength of 12,200 lbs and a safe load of about 1952 lbs. using a 5:1 Safety factor. Don't ask why it is not 12,200/5 = 2440 lbs. cause I don't know!

 

[GregLocock]

desertfox suggests elsewhere - Try this link:-

http://www.slideruleera.net/miscellaneous.html

then go for Uss Wire rope book.

Cheers

Greg Locock


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[Tmoose]

the smaller cable on my come-along sinks into the cable wound on the drum before doing anything useful

 

[patprimmer]

It might be on a winch designed to haul a car onto the trailer, even if the car is broken. It might operate a tail gate or ramps or tilt mechanism or dual level mechanism.

BT and Greg gave the best advice in my opinion.

Regards
Pat
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[pontiacjack]

All answers very helpful- Thanks!