FEA- Determine wrapping pressure of multi-layers of wire rope on winch drum

[heddichead]

Hello Everyone,

Uniform wrapping pressure induced by one layer of wire rope wounding around the drum can be estimated as
P=F/Rm b
P is the line pull tension at each th layer
Rm is the radius of turns of wire rope on drum (PCD/2)
b is the wire rope diameter


This assumes uniform pressure estimated from the wrapped wire rope but in reality due to stiffness and friction the line pull tension will reduce in the following coils so it shall be some sort of pressure distribution formed. In addition, there are no proven formula (rather theoretical or using design factor) to calculate multi-layers of wire rope wrapping pressure.
I started modelling this in Ansys/ Abaqus. Does anyone knows or have experiences in this:
1) How do I model the wire ropes (I.E including solid elements of wire rope in 3D geometry)? In Ansys, what module I can use (ie static structural)?
2) What parameters do I need to model (I.E frictions between wire rope and between drum body and 1st layer of wire rope/ axial and tangential stiffness of wire rope)?
3) What contact interaction properties and modelling methods are available for this?)

Diagrams attached for reference. Thanks for your opinions and sharing.

 

[IRstuff]

Isn't this like a hoop stress problem?

https://en.wikipedia.org/wiki/Cylinder_stress#Hoop_stress

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[heddichead]

Hello IR stuff,

Yes, that is hoop stress induced by the wrapping pressure of the wire rope. It can only be assumed to be uniform pressure by theoretical calculation. However, in practice due to friction and wire rope stiffness the pressure will be less and less as the layer and coil numbers increase. So would like to perform FEA to determine this effect.

 

[GregLocock]

I'd do a handcalc first, FEA would tell me nothing more and would introduce errors.

What are you actually trying to establish with this model?

Cheers

Greg Locock


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[3DDave]

I think you are entirely on your own with this. I also expect the calculations are beyond what you can afford in terms of computer operations. It is a time-dependent, large deformation, non-linear, contact analysis. The typical simplification is to assume that there is no friction between layers and the wire rope is uniformly applied; effectively a sheet of material under tension. This makes sense as it would be the worst case for loading and therefore lead to conservative results. Since the failure of the winch drum would be one of the few devastating failures in a crane or other hoist, being conservative is good.

It's an interesting problem, but it is telling that there seem to be no other links via Google that touch on FEA and wire rope wrapped on drums.

There are a few listings that look like analysis of wire rope under plain tension.

 

[heddichead]

Hello GregLocock & 3DDave,

Have done the the hand calculations. Yes, you are right. It will assume a sheet of material under tension and lead to conservative results. In fact this will be very conservative if we now consider multi-layers piling up to 10 layers. There are no proven formula for calculation of hoop stress under multilayer wire rope. Some design codes propose using safety factor etc.

So, to better find out the hoop stress under 5 layers of wire rope wounding on a drum, FEA is probably the better method.

 

[heddichead]

Hello,

Do you have any experiences in FEA of hoop stress of multi layer of wire rope?

 

[IRstuff]

I would think the contrary is true. It's more likely that a 5 layer wrap would look more like a single monolithic and uniform wrap

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[robyengIT]

IRstuff : I agree with You. The situation is similar to concrete pressure pipes (made according to AWWA C301 type embedded) where an HTS wire is wrapped around a concrete core : if, by calculation, one wrapping layer is not enough, then a second layer is wrapped so that the two layers togheter can withstand the pipe inside pressure

 

[GregLocock]

There have been several threads on this subject, including contributions by people who have actually measured the effect of friction and multilayers. If there is zero friction each layer of the cable is at the same tension, and so the pressure on the drum is proportional to the number of layers of rope, but if mu is sufficiently high then the outer layer detensions those underneath,

I suggest you use the search function.

Cheers

Greg Locock


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[heddichead]

Hello Greglocock,

I searched some discussion on this topic but can't see any conclusion on the effects of friction and wire rope stiffness. Do you have any references and links that has concluded some scientific formula or FEA to determine the wrapping pressure of multilayer wire rope on drum..

Yes you are right. once the wire rope coils increase longitudinally the stiffness will absorb the tension. and also once it piles up radially the friction and stiffness will further absorb the tension. So the wrapping pressure will be smaller when there are said 5 layers of wire rope fully coiled up along the drum.