Just Playing around with some Aramid, seeing how much I can lift with it.
With a view to making my rigging with it.
This photo shows lifting 217 kgs easily, with aprox 35 strands. Each strand is made of aprox 100 individual micro strands.
2 strands holding 20 kgs
The same 2 strands snapped with 25 kgs attached.
At 1 of the 2 knots though.
5 Strands holding 90 kgs
Tony,
That is excellent.
How about increasing the weight until the 5 strands break and confirm that it is over 100kg but less than 125kg.
Also it would be good to measure stretch, but I think double checking the breaking strain of the 5 would be great.
I would have some weights if you need them.
Interesting stuff.
Regards,
Phill
Also test for creep. This is most problematic in synthetic riggging.
Wouter
All in good time,Iam still fairing the boat as well. (never ending)
These experiments are only using a thimble tied off with a knot.
Many hurdles to over come before it becomes rigging, but a nice change from the sanding.
One of the issues with Aramid is getting reliable specs for it. Because of it's use in the military.
The 5 strand test lifted 134 kgs easy.
The same 5 strands then lifted 158 kgs for 5 seconds and broke where it wrapped around 1 of the thimbles. Not at the knot
Not surprsing, since it's normal application is ment for straight lay ups.
In theory I should be able to calculate how many strands are needed for the forces generated. Know the lenght (including creep) Protect the fibres (possible heat shrink )
And work out how to terminate with out bending the fibres.
All good fun. TJ
Tony,
This is all good stuff. Can you explain your comment about wrapping around the thimble. If it was not wrapped around the thimble do you think it would have taken a higher load?
Could you measure this?
Regards,
Phill
Phill
I have been told that the Aramid (Kevlar) that Iam playing with is 10 times stronger than equivilant stainless. For a 10% weight saving.
But only lengtht ways. That is in the direction of it's fibres.
What Iam calling a thimble, some might call an eyelet. The same you would see on the end of any rigging.
It's purpose for the test is to protect the fibres in the strands from abrasions from the shackles and ropes passing through them.
Once the fibres are being pulled from an angle they are not designed for, they loose a lot of their strenght.
So I have to determine accuratley haw many strands will support the rig. Once I know the diamiater, find a suitable sleeve to protect the strands. And find a way to terminate the ends with out changing the direction of the fibres.
A strand is aprox 1mm thick under load and is made up of hundreds of individual fibres.
TJ
Tony,
I see what you mean.
Just the act of the fibres bending around the curve in the thimble.
I wonder if the weakness is cause by them cutting into each other or individual fibres within a strand under load or just the fact they are bent.
I don't suppose it matters, unless the knowledge can change the result.
The other method of termination you mentioned to me seemed a bit suspect at the time but given the way your testing is going it's starting to look like an option worth testing.
Interesting stuff.
Regards,
Phill
Plain high strength steel will pull 60 kg per 1 mm circular crossection before breaking. As such 5
strands
of steel will pull 150 kg with a safety factor of 2.
Going on your test results then the aramid is not very impressive. It is certainly no where near 10 times stronger as steel.
Wouter
Wouter.
Iam having a bit of fun, I quickly rig a test, break it and move onto something else. To date 1 hour maximum on the whole project.
When I finish my hulls I will spend more time and be more accurate. It may come to nothing, but it may just work.
Time will tell.