Titanium Bolt Failure
Titanium Bolt Failure
(OP)
I have a climber with two broken feet.
He was clipped into a Ti bolt that was installed in a rock ceiling.
I need to know how to calculate the stresses on this part for a failure analysis report, but the math is a little fuzzy.
Here is the bolt in question:

Here is one end of the bolt that failed.
The shaft is still in the rock.

Here is a Free Body Diagram I drew of what is happening:

I believe that the eye should be aligned with the shaft so as not to introduce a sheer component.
How do I calculate the sheer pressure of the guy weighs 210 lbs and the Ti bolt is 3/8 shaft, with a 1 inch offset.
Also, does it matter if the shaft is hanging out of the rock?
I say it is better, the shaft can flex and distribute the sideways component, where as a coleague says that any additional length will facilitate failure, as more leverage is present.
I think, depending on the Modulus of Elasticity, that it would be easier to snap he bolt if it were installed flush, as there is a small bend radius at the glue in point?
Thank you for any help in analizing this mathematically.
How would I compute the stress for differen lengths of shaft hanging out of the rock?
The bolt was made by USHBA.
It is bent from round stock Ti alloy, I do not know the mix.
It is also welded, another question mark.
Ti is tough to weld.
Thanks!
He was clipped into a Ti bolt that was installed in a rock ceiling.
I need to know how to calculate the stresses on this part for a failure analysis report, but the math is a little fuzzy.
Here is the bolt in question:

Here is one end of the bolt that failed.
The shaft is still in the rock.

Here is a Free Body Diagram I drew of what is happening:

I believe that the eye should be aligned with the shaft so as not to introduce a sheer component.
How do I calculate the sheer pressure of the guy weighs 210 lbs and the Ti bolt is 3/8 shaft, with a 1 inch offset.
Also, does it matter if the shaft is hanging out of the rock?
I say it is better, the shaft can flex and distribute the sideways component, where as a coleague says that any additional length will facilitate failure, as more leverage is present.
I think, depending on the Modulus of Elasticity, that it would be easier to snap he bolt if it were installed flush, as there is a small bend radius at the glue in point?
Thank you for any help in analizing this mathematically.
How would I compute the stress for differen lengths of shaft hanging out of the rock?
The bolt was made by USHBA.
It is bent from round stock Ti alloy, I do not know the mix.
It is also welded, another question mark.
Ti is tough to weld.
Thanks!





RE: Titanium Bolt Failure
If you are going to court with this get a professional.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Titanium Bolt Failure
modulus,
Did by any chance, that bolt fail at the last thread, before the plain shank started?
B.E.
RE: Titanium Bolt Failure
You need a proper failure investigation done (ie) metallurgical analysis, etc.
RE: Titanium Bolt Failure
Yes it appears that the shaft was broken at the last thread.
This bolt had been installed four years ago.
In order to test it, many falls were taken, which would have introduced a dynamic load, as opposed to just hanging there.
I am thinking that since the rod was bent one way, and the load bent the rod the other way agfter installed, that thisa is the equivalent of bending a coat hanger back and forth.
Also, 210 lbs is not a heavy load, these things are supposed to take 25 Kn.
A German Lab did some tests and three out of five failed due to shaft breakage at 9 Kn.
I have a pic of the cross section, it just looks like shiny fine crystals with an outer oxide, no cracks or anomalies present.
There is no CE cert for bolts, unfortunately, so any old Joe can get into this bussiness.
As fa as Liability, I really doubt that the victim is going to go forward with a suit.
He has medical, and is healing fine.
And most insurance companies do not cove climbing, as it is considered an Extreme sport.
Just want to explain to some of the climbers that this thing is not safe!
M<any are blaming the installation.
I feel that a Personal Safety device should have some anti-murphy nuilt into it, just in case somebody does not install it perfectly.
Thanks Again!
Modulus
RE: Titanium Bolt Failure
Ted
RE: Titanium Bolt Failure
RE: Titanium Bolt Failure
RE: Titanium Bolt Failure