Questions regarding microfracturing

I know I'm going to get a lot of flak for this post, but I have some genuine questions.

I know (having had the fact shoved in my face a couple times) that within the normal life of hard climbing gear, microfracturing is not a concern. What I would like to know is, what kind of abuse would be needed to start getting gear to that state? Also, would it be possible for the anodization to hide such material flaws?

By abuse, I'm not talking about grinding carabiners against rock, or using hard gear as makeshift nuts, but rather abuse on the scale of "let me toss this in a kiln and then toss it in a pool" abuse.

Of course, this is all theoretical, as in normal usage, we would not subject gear to temperatures where the material properties even start coming into question (I hope, but on that question, would keeping such gear in polar conditions affect it?)

ntlhui wrote:I know I'm going to get a lot of flak for this post, but I have some genuine questions. I know (having had the fact shoved in my face a couple times) that within the normal life of hard climbing gear, microfracturing is not a concern. What I would like to know is, what kind of abuse would be needed to start getting gear to that state? Also, would it be possible for the anodization to hide such material flaws? By abuse, I'm not talking about grinding carabiners against rock, or using hard gear as makeshift nuts, but rather abuse on the scale of "let me toss this in a kiln and then toss it in a pool" abuse. Of course, this is all theoretical, as in normal usage, we would not subject gear to temperatures where the material properties even start coming into question (I hope, but on that question, would keeping such gear in polar conditions affect it?)

Microfractures do not occur in modern climbing gear, regardless of how much you abuse the gear. You would not able to create a microfracture even if you tried. This was more of an issue 20+ years ago when aluminum manufacturing techniques were less refined than they are today. Small cracks from cyclic loading (fatigue) can occur in climbing gear, but not when used for actual rock climbing. You would need to be using the gear for a different application, such as rigging a permanent slackline or overhead lifting, for fatigue to come into play. Dropping the biner off El Cap, no matter how many times, would not cause fatigue.

The key phrase is "normal life."

Crack formation, growth, & ultimately equipment failure is well known in the climbing world.

Cracks form in crampon toe bails. theuiaa.org/index.php?page=344 (Do you remember: 1) When you purchased your crampons? and 2) How many seasons the manufacturer designates as "normal life"?)

Stress corrosion cracking is one of the failure modes of bolt anchors. theuiaa.org/upload_area/Saf…
Which begs the question of what the normal life of a bolt might be...

For a recreational climber, the carabiner will outlast the climber's lower back by some time, but if an aluminum carabiner is loaded often enough, it will fail by the formation and growth of cracks.
web.mit.edu/16.62X/www/Okal…

And swinging an ice ax into hard surfaces like ice is a fine way cause cracks to form.
link.springer.com/chapter/1…

dave custer wrote:... For a recreational climber, the carabiner will outlast the climber's lower back by some time, but if an aluminum carabiner is loaded often enough, it will fail by the formation and growth of cracks. web.mit.edu/16.62X/www/Okal… ...

Very interesting paper. I presume this was for a structural/civil engineering or mechanical engineering class at MIT?

I have to agree - I don't think many climbers would quite enjoy a couple hundred lead falls that weren't nicely caught.

It would be nice to see the future work as suggested in the paper. I wonder if any has been done in the five years since...

ntlhui wrote: I wonder if any has been done in the five years since...

Yes, but it's all moot. The 7000 series Al used in climbing gear has been very, very well tested in the airline industry and as a result its properties are well understood. As aircraft is also made from 7000-series aluminum, Boeing has probably invested more research money into R&D than all climbing manufacturers combined.

20 kN wrote: Boeing has probably invested more research money into R&D than all climbing manufacturers combined.

Super true.

20 kN wrote: Yes, but it's all moot. The 7000 series Al used in climbing gear has been very, very well tested in the airline industry and as a result its properties are well understood. As aircraft is also made from 7000-series aluminum, Boeing has probably invested more research money into R&D than all climbing manufacturers combined.

Boeing's annual R&D budget was over $3B last year. In 2009 they spent over $6B on R&D. Granted, that's across all fields and verticals, but it's safe to say that Boeing spends more on materials R&D in a single year than all climbing manufacturers have ever spent in their lifetime collective totality.