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Why stuff breaks


crazyjizzy

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Carabiners break when they suffer a blow, casting defects, or undergo loading in a gate open position. Years ago, Yates Screamers were resposible for many carabiner failures because as the stitches blew, the gates would rattle open, and the biner could eventually break. This happened to us on a early ascent of the ZM when a fixed RURP with a rip runner held, and the bean broke. To aleviate this people started using lockers, or the newer wire gates. Wire gates are much less likely to come open in the above scenerio due to their lesser inertial mass.

 

I don't think any climbing rope would act as a static rope during a zipper fall. The rope would rebound quickly, and more importantly, the rope would stretch a fucking mile. I have tied ropes to Cat D4's and the other end to a tree, and they will stretch and stretch, and stretch. Aid climbers have taken lots of rippers, and if ropes lost their dynamic ability part way thru a zipper, then the impact force would kill the poor fucker that fell.

 

With the exception of highly fracured, rotten, or poorly indurrated sediments I think that cams fail when they are poorly placed. Period. I believe that the friction between the cam and the rock is always greater than the force on the cam. Even in Indian Creek, where you can see "skid" marks of cams resulting from a fall, it is the underlying sandstone that is failing, not the frictional interface(senso stricto). The rocks of the Columbia River Basalts are much stronger the the sediments of the Colorado Plateau.

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You can find an MIT grad student's investigation of carabiner failure here:

 

http://www.mit.edu/afs/athena/course/16/16.62x/www/Graham_Jon_622.pdf

 

For info on rope/knot/cord failure check out this site: http://www.xmission.com/~tmoyer/testing/

 

More info on 3-Sigma Testing:

http://www.bdel.com/bd/quality_3sig.html

 

Some info for heavy climbers:

http://www.safeclimbing.org/Heavy_Climbers_Beware.pdf

 

Great general tech weenie site for climbers:

http://www.fishproducts.com/tech/techweenie.html

 

Petzl Fall Force Simulator:

http://www.petzl.com/statique/sport/ENG/tech/html/simul/FC/index.html

 

Good info on shockloading:

http://www.petzl.com/statique/sport/ENG/tech/html/shockload.html

 

Other techy type links about gear/climbing out there?

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