Plastic Pipe Crushing 1

[bangerjoe]

Hi,

Bit of an oddball one. I would like some advice if possible.

Client has a sheave block which supports rope over a 90 degree bend. (see below)

They're taking the sheave out for servicing and don't want it to bend over a sharp radius (fair enough) and have asked for a length of plastic pipe to be used to support the ropes.

i have checked and the pipe is adequate in terms of min. radius for the rope.

although not heavily loaded (self weight of pipe only - tension is removed), how would one check the pipe for crushing?

i do have mechanical specifications of the pipe, i.e. tensile modulus, poisson's, and yeild stress.

i can work out the resolute force being applied, but have never come accross checking a pipe for local damage like this (traditionally treated them as a member or subject to hoop stress).

Regards, Joe

 

[LittleInch]

Why don't you just fill the pipe with concrete?

"plastic" is very vague. Just make it solid and your problem goes away.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[BSVBD]

Why can't you use steel pipe?

 

[dhengr]

Bangerjoe:
I’d take a 3' long piece of 6-8" dia. oak log or a landscape/cribbing timber for that matter, and rip it down the approx. middle, to produce a flat side. Bolt this to the deck (or whatever) with some overhang on the outer edge. If it is a rectangular timber, rip one corner to 45̊, and round the remainder of the corner. Put a couple half round 2x10 end plates on it to retain the rope, and call er a day.

 

[bangerjoe]

Littleinch: plastic on hand, looking for a cost effective way.

BSVBD - see above re: material. for steel i would have a similar problem: i haven't come accross the load case on a pipe.

Dhengr - although i agree timber is suitalbe outside scope.

Further info Pipe is approx 500 mm OD, agricultural type

 

[JStephen]

In Roark's formulas for stress and strain, there are a number of different load cases for circular hoops that can also be applied to long tubes with uniform loading. The catch is whether any of the choices given can be superimposed to get some semblance of your actual loading. Two loads acting on a diameter may be as close as you can get.

 

[bangerjoe]

Thank you Jstephen

 

[LittleInch]

Like I said - plastic pipe, filled with concrete. Sounds pretty cost effective to me.

Beware of the creep properties with PE at least. what starts as a round pipe, might be an oval one after a couple of days...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[XR250]

How are you going to keep the pipe from moving to the right?

 

[bangerjoe]

@XR250 i will lash it.