Proof load UHMW polyethylene 1

[Verkstad]

Hi,
I am used to work with proof load for metals. But when i look for proof load for plastic i do not know what that mean.

When i looked at one site they said that UHMW polyethylene had a proof load of 18 MPa at 50% deformation. My question is what does proof load mean for a polymers such as UHMW polyethylene? And how many cycles can you reach the proof load?

 

[Verkstad]

It hit me that you can look in a fatigue curve to get a felling for it. With metals you may get stress concentration and plastic deformation. Because of the plastic deformation the stress is distributed on a larger area and the stress is reduced is it the same with polymers?

 

[EdStainless]

With un-filled polymers they begin deforming from almost any load.
There is no defined yield point in a polymer.
You have to look at your loads and determine what the creep will be, and if you can live with that.


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P.E. Metallurgy, consulting work welcomed

 

[Tmoose]

"There shall be no cracks or permanent deformation greater than 1/8”."

https://www.trumbull-mfg.com/wp-con...Specs-20K-Plastic-Meter-Pit-Lids-10-03-22.pdf