Discussion Topic |
|
This thread has been locked |
graniteclimber
Trad climber
Nowhere
|
|
I wrote: " Also, you don't know that he grasped the device during a fall."
Ain't No Flatlander responded: "According to NorCal, that's exactly what he did."
Edited because I was wrong: Nor Cal said " he grabbed the rope during his fall and this prevented his ushba from camming into place."
Ain't No Flatlander is right that the accident was user error.
|
|
Hardman Knott
Gym climber
Muir Woods National Monument, Mill Valley, Ca
|
|
As I remember it, Nor Cal said the guy grabbed the rope, which prevented the device from locking up...
|
|
Dr. Rock
Ice climber
Castle Rock
|
|
If you go down to OSH and look in the Fastner section, you will see that even the 79 cent galvanized eyebolts from China are built with the eye along the centerline.
In fact, I do not recall ever seeing a design of this type.
This is not rocket science folks, you have Gravity, you have a Load, which creates Stress.
You have a piece of hardware that has a load rating.
When the Load is Exceeded, the Apple falls to the Ground and breaks his feet.
I mean I can see Mongo the Caveman, out climbing.
Mongo fall on wood bolt.
Mongo hurt knee.
Mongo build bigger bolt.
Doh, ...
We are going to Mars pretty soon.
Can we build a good piece of hardware from 1920, or is that too much to ask?
As soon as you put the eye off center, you are loading the shaft with a vertical component as well as a horizontal.
It does not like the vertical, or "sheering" load.
wrong.
|
|
Hardman Knott
Gym climber
Muir Woods National Monument, Mill Valley, Ca
|
|
Dr. Schlock wrote:
Mongo fall on wood bolt.
Mongo hurt knee.
Mongo build bigger bolt.
Dr. Schlock finds this thread.
Dr. Schlock doesn't know shít.
Dr. Schlock keeps on posting...
|
|
jstan
climber
|
|
I read enough of the thread to reach the one reporting the weld did not look like Chiloe's stacked coins but was like a blob, and it cracked.
A suggestion. This bolt should have been rejected at manufacture. Welds need to be closely controlled especially in a material with less experience in the field than possessed by steel.
If a part with a problematic weld was released from production one might expect there may have been other problems during manufacture of this unit. If corners are being cut, it is unusual to find only one corner has been so handled. If you still have the bolt, materials analysis would appear to be in order. Hardness, impurities, grain size, yield modulus etc, etc,etc. And if at all possible, have the analysis done by a vendor who makes personal safety equipment in titanium. Only they will be adequately familiar with the ins and outs of working this material. It may be the needed technical experience exists in Thailand if that is where this material is being used extensively.
Send both parts for analysis!
|
|
Dr. Rock
Ice climber
Castle Rock
|
|
The bolt should have never been released for production in the first place.
It is a faulty design.
The good weld was from a part that was shown at the USHBA website.
But again, the weld is not the problem.
A simple tack weld, however, where the loop rejoins the shaft, would have been better.
It would be plenty strong to hold the loop closed, but would not heat up the part as much.
You have to flip that part when you weld it 360.
With Ti, you have to keep the Argon gas flowing over the weld during the flip over.
If you don't, you lose coverage and the weld cracks.
USHBA is aware of the problem.
Mr Slime is aware of the problem.
Now, thanks to the internet and the wonderful forum, the climbers are aware of the problem.
At this point,it's all about Damage Control, thus, the visits from the Manufacturing Sector.
When you design products for Human Safety, you better know what the H you are doing.
And test the Hell out of it.
Hopefully, the people climbing in Thailand do not weigh as much, and I hope they are over the ocean.
Easier to get away with stuff in a foreign country, eh?
What are they gonna due, fly over and file a lawsuit?
Not with these gas prices.
|
|
stevep
Boulder climber
Salt Lake, UT
|
|
Seems like a lot of assumptions about their weld process. Ti is certainly not easy stuff to work with, but that isn't to say it can't be done right, and I'm not clear that the problem in this case was manufacture.
If the bolt had simply broken, I'd be much more inclined to say bad bolt. But I can't really think of any way that bend gets there other than the bolt shaft was exposed more than it should be. And again, Petzl says that is bad for their steel bolts as well.
Be curious to see what the feedback is from Thailand on this. I believe there are quite a few of these in a horizontal roof at Tonsai. Seems probably a better sample to draw conclusions from than this single incident.
|
|
Dr. Rock
Ice climber
Castle Rock
|
|
Steve, remember when I said that it would be better if the bolt wer Not installed all the way?
Look back at that Free Body Diagram.
The more shaft exposed, the more metal to bend and take the strees.
But when an offset eye is set in to the the limit, you have all that leverage in the X direction, which is what broke the bolt.
Remember, theses guys were testing the thing by jumping off of it.
This no doubt, because of the design, started the bending process, which continued until the the ultimate load was reached.
I do not like seeing bones sticking out of peoples legs, thus the interest in this thread.
|
|
dirtineye
Trad climber
the south
|
|
DrRock, YOU ARE AN IDIOT.
You are WRONG about the shaft sticking out being good.
Torque = the product of a force and the length of the lever arm, and you'd know that if you had any background at all for this stuff.
Making the shaft longer is WORSE. Embedding the eye up to it's neck is what you want.
GO here and see if you can comprehend.
http://en.wikipedia.org/wiki/Torque
|
|
Dr. Rock
Ice climber
Castle Rock
|
|
I am Not an Idiot.
I am a Moron, remember?
An Idiot has more Brains than a Moron.
Look it up.
Don't give me more credit than I deserve.
But the Internet is full of people better looking and smarter than me, I can use them to help me, right?
That is the purpose of the Net, at least originally.
No seriously, imagine clamping a nail in a vice and bending it back and forth til it breaks.
Which is going to be easier as far as breaking it off is concerned, grabbing it at the nearest point to where it is clamped, or grabbing it at it's end?
If you grab it at the end, the bending can be distributed along the portion of the nail that is exposed.
If that portion is very short, like when you grab it at the vice, then you have very little steel to help share the load, get it?
It is going to see a Sheering Forced, not a Tension Force.
We want the Tension Force, but the Sheering Force we do not like.
We try to design that variable out of the product.
Go back and stare at that diagram for how ever long it takes.
A picture is worth a thousand words, the failure mode is cleary visible.
Now go down to the Hardware Store and look at eye bolts.
See how the eye is lined up with the shaft as to not put any sideways pressure on it?
You got the most fit people in the world, maybe even the smartest, they are out enjoying nature, and the wonderful body and landscape that God sent them, they are doing the most natural and organic thing you could possibly due in life, climbing. Everything is wonderful in this fantasy like world, then something brings you down to Earth, literally. What is it?
A component designed by some guy that spent his life climbing, noticed that it did not pay very well, although it was a lot of fun, as well as a lifestyle, but I am getting old, what to do?
Start a company that sells rock climbing equipment, get some friends together, get some QBE engineers, go have a drink or two, start the company, put out a bad product, and retire to the poor house early becuase of all the laws suits you forgot about.
Im just hope this guy did not get any of your money.
Bummer in the summer.
Beter luck at you next venture, I hope it pays.
|
|
dirtineye
Trad climber
the south
|
|
Dumbass, you still miss the point.
You are clueless, and have NO understanding of what is going on there. Copy all the crap off the net you want, you still won't understand it any better than a trained monkey would.
If the eye is embedded and glued the way it is supposed to be, BOTH ARMS of the eye will take stress, as opposed to your idiotic notion that it is good for the single shaft to be under stress.
One more time, the further that shaft sticks out, the more torque you can put on it. That's bad.
STFU.
|
|
Dr. Rock
Ice climber
Castle Rock
|
|
Ahh, I see what you are saying.
With the shaft hanging out, there is more leverage on the part.
Yes, that is true.
Hmmm, let me thing about this for a bit.
Meanwhile, try and visualize a Karate guy breaking a board.
What if the board were held by supports that were ten miles apart, would the board bend when he hit it, or would he snap like through it?
What would happen if the board were supported by a couple of cinder blocks that were only 6 inches apart.
So you have a point, I have a point, interesting problem, shaft flex vs leverage, which is worse?
Dirt, imagine the same bolt in a ceiling, only hanging down from it's now longer shaft by ten feet.
What would happen when you hung a load of of that thing?
Would the shaft flex gradually over that ten feet, evenly distributing the horizontal vector, or would it do the Snappy Gator?
I do not mind a little conflict BTW.
I have been in forums were everybody agrees with one another, and everybody is nice, but nothing gets resolved!
And it is boring as hell.
So yeah, if you are new to the forum bidness, it can be a rough ride folks, try not to make too many enemies, you never know who is out there, this one forum, ol Fletcher over at Gear Slutz was gonna call the Hells Angels out because a guy insulted his wife, it can get pretty ugly and maybe dangerous, so it is a good idea not to use pics or your real name, just in case, if you have ever met someone from the internet, you know what I mean.
|
|
dirtineye
Trad climber
the south
|
|
You
Still
Don't
Get
It.
IDIOT!
Did you not see the earlier posts about bending a rod of any sort enough times? Metal fatigue always wins, because metals are not self repairing, like organisms. Now, if you had a bolt that could heal itself, then you might have something, but you don't. Nobody does. They don't exist. Am I making this clear enough for you?
Hey DrDumba$$, imagine how nice things would be if Pi were three. Hell, the bible says it is. Imagine how much easier things would be then.
And what if 2 + 2 could just equal whatever you wanted, instead of coming out that pesky old 4 every time.
As for meeting you, I'd love to. It would be a rare experience.
|
|
jstan
climber
|
|
Imagine a right circular cylinder, a bolt, bent over a circular mandrel. Now the end of the cylinder that is bearing the weight is not going to suddenly look as though it had been cut on an increasing angle as the bolt is bent further around the mandrel. Think about it and you will see materials don’t distort that way. The end stays square. Now let’s say the mandrel is six inches in diameter and the bolt is 0.5 inches thick. The side of the bolt contacting the mandrel will wrap around the mandrel in an increasing angle of bend. If we express the angle in radians we can measue out the length of that side of the bolt that is in contact with the mandrel. Our old friend
S=rø
So if we wrap through an angle ø on a six inch diameter( radius 3 inches) the length of the bolt contacting the mandrel will be
S1=3*ø
But the far side of the bolt will be bent over a radius one half inch larger so the outer surface will have a length
S2=(3+0.5)*ø
OK so the outer surface of the bolt is being stretched relative to the inner surface. This is a dilatation and what is the fractional dilatation? It will be
(S2-S1)/S1=(3.5ø-3ø)/3ø=0.17
Cool, but let’s bend the bolt around a 0.1 inch mandrel. Then the fractional dilatation of the outer surface of the bolt will be
(S2-S1)/S1=(.51ø-.1ø)/.1ø=4.1
Twenty five times larger and we now have to worry about that outer surface exceeding its yield modulus and the bolt failing.
Now here is something more interesting. If you let the bolt stick out six inches the eye will move a whole lot but the radius over which it is bent out in the extended shaft will be something like half the distance it sticks out. The fractional dilatation won’t be all that much even though it moves a lot. Materials fail when their modulus is exceeded not when a long length of it bends a long distance.
In order to apply this to the bolt in question we need to know the actual geometry. If you have that and you look up materials data on titanium having the temper possessed by that bolt, you can do a calculation.
My guess? We don’t know the properties of the material in that bolt at the point where it failed.
A friend of ours fell while climbing and shattered her heel bone beyond reconstruction. In her case she subsequently ran into auto-immune problems. You really don’t want to damage your feet this way.
My advice? When you are with a big group of people whooping, hollering, and acting like they have nothing to fear down there, take care to realize they are correct. You are the one who has something to fear. I had a second once who took it into his head to yell at me and urge me to go for it when I was busy figuring out the move. You run into people like this who know zip and think cheering someone on to risking their neck is cool. Avoid them. When things get serious you don’t want them around, anywhere around. The further away the better. The next state is not far enough away. Next galaxy…..that’s OK. Two or three galaxies away ….now that’s getting better.
|
|
Dr. Rock
Ice climber
Castle Rock
|
|
Cool on the Polar system, been a while.
One rev is 2 pi radians, right?
Idaho National Engineering and Environmental Laboratory
* Improper use of rigging gear can result in equipment damage, personnel injuries, and even death
* So-called “experts” sometimes aren’t
* Guidance and standards can be misleading
* When in doubt, stop work and start asking questions
(and a little bit about proper use of shouldered eyebolts, too)
Oh, wow:
"It should be noted that bolts do not come under the category of Personal Safaty Equipment and therefore do not require independant testing and carry no CE mark."
Open season.
Ushba Bolt (Buhler type glue-in developed for Thailand to overcome the corrosion problems)
Material. Titanium:10mm dia. 5 tests. 9kN, 9kN, 10kN (all broke at eye weld), 24kN, 34kN.
From Bolt Products.com:
"Welded Eye Bolt
Usually threaded on the shank to provide a good bond this is a traditional design which comes in and out of popularity. While a number of these have proved to be reliable there are two areas of concern. The first and main one is the welding, without correct material selection and a very experienced welder this will always be a weak point, with too rapid cooling of the weld area leading to cracking and failure of the shaft itself. The DAV have tested a large number of these (a home-made series) and had shaft failures as low as 50N! "
FMI:
Here is a table of the range of strengths for typical rock types.
Unconfined compressive strength:-
Granite 100-250 N/mm²
Basalt 100-300 N/mm²
Quartzite 150-300 N/mm²
Sandstone 20-170 N/mm²
Shale 5-100 N/mm²
Limestone 30-250 N/mm²
Marble 100-250N/mm²
Slate 100-200 N/mm²
Quartzite 150-300 N/mm²
Concrete 14-42 N/mm²
High strength concrete 70 N/mm²
"Myth 4:- Titanium is light, strong and corrosion resistant. Pure titanium is in fact quite weak and soft, ASTM grade 1 having a tensile strength of only 240N/mm². (`mild´ ASTM 1018 steel is 440N/mm² ). Alloyed with aluminium and vanadium (grade5 for instance) gives the highest tensile strength of 896N/mm², about the same as cold worked stainless steel and chrome-molybdenum. Unfortunately in this condition it is prone to stress corrosion cracking in the presence of salt so for sea cliffs one needs to add palladium, ruthenium or possibly nickel. A good choice for pitons would be something like grade 27, a `low´cost titanium/aluminium/vanadium/ruthenium alloy.
`Low cost´ is relative as ingot prices start in in the hundreds of thousands of dollars per ton and I would expect to be paying over €300,000 per ton for rolled material!
|
|
perswig
climber
|
|
What's the possibility this bolt suffered some 'creep' from it's glue bed over time?
Vertical placement, repeat body-weight loads plus random falls. Installer says placed at correct depth; no rock fracturing, etc reported during post-break inspection; some of pre-break pics show shaft visible; fracture appears at/close to first groove in shaft; some question of position of 'eye' in pre-break pics vs. direction of fracture.
If the glue binds to rock but not to the bolt; if the bolt were placed in a way (too little rotation during installation, after glue had started to solidify, whatever - I can see this being difficult to do timing-wise in this position) that doesn't allow the glue to fill the relief grooves, just creates a cylindrical bed.
Can this allow rotation of the bolt in place? Can the bolt migrate until enough of the shaft is revealed to allow repeated stress to fracture at an obvious and unintended weakness (the groove), regardless of all the metallurgy, weld specs, etc.
Just asking.
Dale
|
|
jstan
climber
|
|
Well, Doc, I think you may be getting somewhere. Heat processes and alloy segregation become a huge liability anytime you are working an alloy like this. Besides the weld this material has to be heated to form the eye. They may get the heating and cooling right to make the eye strong but what about the shaft? Presumably such a product would have to go through a carefully controlled annealing to rectify such problems. Then if it is a personal protective product you need to test a big portion of the product stream to destruction to get the needed statistical confidence.
I expect GE spent billions to develop the materials technology that made the jet engine possible.
We like to think technology has allowed us to distill climbing down to just the endorphine buzz. The risk component can be driven off. There is risk in gymnastics. Plenty of risk. Gymnastics, IMO, is to climbing like the jet engine is to this bolt. What we are doing in climbing is really very crude.
As Jay Wood notes there is risk in my using this computer. Risk is a part of life. That is what I liked about trad climbing. You actually got to choose how much risk you would undertake and then you could learn to function with safety acceptable to you in that environment. Climbing was not about difficulty ratings. Ratings never were anything more than a toy for people who did not realize what it is they were really doing.
We are learning to be aware of our surroundings and learning to live and function in those surroundings. Exciting stuff,
|
|
stevep
Boulder climber
Salt Lake, UT
|
|
The lever arm is worse for the bolt. Again I refer you back to the Petzl spec. They clearly recommend against leaving the shaft exposed in their symmetrical stainless bolts. So material and eye design might have an impact in failure, but unless you also think Petzl's engineers have it wrong, having the shaft exposed where it could be bent is a bad idea regardless of material.
If someone can come up with an alternate mechanism for the bending of the shaft in this accident, then maybe I'll start worrying about large numbers of these bolts being bad.
|
|
JLP
Social climber
The internet
|
|
"Twenty five times larger and we now have to worry about that outer surface exceeding its yield modulus and the bolt failing. "
If the metal stayed bent, it yielded.
"If you let the bolt stick out six inches the eye will move a whole lot but the radius over which it is bent out in the extended shaft will be something like half the distance it sticks out"
You have either forgotten Mohr's Circle, or never been exposed to it. This allow a radius thing isn't even academic.
More to the point, anyone with a 1/2 oz of experience will immediately recognise that any bending or torsion will greatly magnify stress at the ring feature - the feature that actually failed.
|
|
|
SuperTopo on the Web
|
Let us know!