Are MicroFractures a Myth in climbing carabiners? 

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Micro-fractures exist, but I doubt you can get them by ground hits. The main mechanism that produces micro-fractures is fatigue. Aluminium is highly susceptible to fatigue by repeatedly stressing it close to it's yield strength, a.k.a. a few very bad falls with at least 75% MBS force and no deformation. But that would be a different test. Sorry to get all technical and I have great respect for the practically scientific side of this channel.

You should team up with one of the "ultra-high speed camera" channels to get very slow-mo footage of the breaking equipment. Watching a crack propagate thru a device often reveals interesting insights. Great channel. I never climb, highline, or slackline, but I command a Urban Search And Rescue (USAR) crew so I enjoy watching your destruction testing and your diligence on safety. You're an excellent role model. Thanks!

I am a mechanical engineering student and have studied material sciences as well as mechanics of materials. So, within these topics it looks all the way down to the crystal structure of materials and how they behave to how different loads will cause different stresses within materials. I can say from these classes that THERE ARE MICROFRACTURES. When a force is added to an object stress can be visualized as “flowing”. When ever there is a little defect in something the stress flow is compressed like if you were to see a river try to flow around a rock. This causes a concentration of forces where there is a small defect. It is completely dependent on the geometry of the crack and how the stress flows through the object. So, for the carabiner there could definitely be some sort of stress concentration depending on the types of chips and cracks in it. This is probably why there was a bigger range of failing forces because there were different chis in each of the carabiners. From this abuse there is more likely to be dull dents and chips which have way lower stress concentrations than a sharp crack since the stress can flow around a circle better than a sharp point. What is probably more likely to make the fractures is causing lots of stress then reliving it. This can lead to the “microfractures” that aren’t really visible. Each time the material is loaded to a high amount these cracks can propagate and weaken it. There are graphs for different materials called S/N Fatigue curves that show different loading cycles and how many times they can withstand those loads. So, in the case of these carabiners they can take so many falls and will form small “microfractures” within the material that will eventually fail. This was the cause of an aircraft accident since the cabins are pressurized and depressurized causing a loading cycle. There is a good quick video that covers some if this linked below. With this being said it might be a better experiment to put a load of a bad fall on a single carabiner then relive it. Do this multiple times and then test the maximum breaking force or continue to do it until the carabiner fails. Another point I would like to make is that there was somewhere in this video that quickly mentioned the maximum breaking force to be much higher than what is labeled. There is something called the factor of safety that engineers use when designing a product. The product has a requirement that it must be able to withstand. The requirement is then multiplied by the factor of safety and then designed to meet this new higher load. The product is then labeled with the load required not what it was designed to. This is so if something happens that is accounted for or someone uses it improperly there is still more strength than what the end user really thinks there is but never load something beyond what it is labeled. In the case of these carabiners they could also be labeled with the standard minimum they go by so people know that it is safe enough. I hope this helps! Different equations for facture mechanics and stress concentration from them: en.wikipedia.org/wiki/Fracture_mechanics Video on plane windows: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-7rXGRPMD-GQ.html Plane accident from fatigue: lessonslearned.faa.gov/ll_main.cfm?TabID=4&LLID=20&LLTypeID=2

For future video can you break test some cheap “climbing” carabiners off Amazon that use the CE rating?

These tests are so awesome! I'm a climber, rope access tech and professional rigger and these vids are SUPER RAD! Thanks so much! It would be interesting to drop a carabiner from 100ft and the xray it first to see if there are micro fractures and then break test it. I'd love to see that... I might be able to get the xrays done and then send the biner to ya to break it!

Love the channel and this series. Micro fractures are a real thing, and there are material science equations that can calculate the minimum size of a surface defect that could lead to failure under different loading scenarios. Older carabiner were manufactured without a specific design for avoiding microfractures. Newer carabiners are a lot less prone cracking, and the minimum crack size for failure (usually) is visible to the eye. If you see a crack or large dent, retire the gear, they fail fast when they go and don't give visual warning they are about to.

Thanks for taking the time to fully prep, test, and share this information Ryan and associates. Appreciate the bit of knowledge and entertainment for sure.

12:58 Sure, we need more testing (ie more Patreons) to get a more precise average. But, still, in both models, we can see that one out of 3 got impacted by the abuse. So, kids, take care of your gear, but don't replace it every time it touch the rock either. Very great video, thumbs UP as always. Alex, whitewater rescue instructor in Québec.

The animation in this one is amazing!

By far my favourite channel on youtube, thank you for being you..🏆

That was very cool ! So interesting. Should be very interesting to watch the carabiner rupture with a very high frequency camera, in order to detected the initiation of cracks.

I love these climbing related slack snap videos very entertaining thank you.

I would like to see this with carabiners dropped from a signifact height, like 25-100 meters or so. Not just smashed a little bit to the ground.

Next time have Bobby take whippers on the carabiners, then test them.

I don't have any clue how I got this recommended but I'm not disappointed at all, I've watched a few of your vids. I don't do any rope work, or certainly not any highlines.I used to be a Firefighter I've used some ropes and harnesses, mainly Gemtor 541NYC harness with Petzel ID Rig or Rescue8...all very minimal expierence with it. I like the ground pretty good, that and knots aren't my strong suit, awesome as crap vids yall.

Good video!! Thanks this will help as the conversation at the crag always end up to this subject. Thanks a lot! :)

Hi, it would be wonderful to see the difference between climbing knots. There are many and we all know that it has a big effect on the rope strength

From this kind of abuse, it seems more likely that the result would be Work Hardening of the aluminium. there is a wikipedia article from this, and quoting the section on aluminium: "Devices made from aluminum and its alloys, such as aircraft, must be carefully designed to minimize or evenly distribute flexure, which can lead to work hardening and, in turn, stress cracking," That being said you'd have to repeatedly be causing impact stress on the aluminium to normally cause that to happen (to my knowledge). It's possible it could worsen a very minor defect in grain structure eventually though.

Interesting experiment, but due to the limited number of tests it really only shows that microfractures are not guaranteed to occur when throwing biners around.. Not trying to tell you to destroy more carabiners though ;)

That’s very interesting. Thanks for the testing, I’ve always wondered 🤔

I'd be interested in seeing High Res Pics of 824 and 830 to see if there was some deep gouge near where it ended up breaking since those are both the "outliers" in this experiment.

I used to work for a boutique bike frame builder in San Diego back in the 90's making custom steel, and then Ti frames. Aluminum has a "quality" called catastrophic failure. Really sucks on bicycles. Probably does when a biner fails also.

so just throwing them on the ground is not gonna be enough, they need to be thrown down and then cyclic loaded for years for them to be compromised. possible micro cracks are gonna take many many cycles to grow. I'm a machinist and Ive seen this in engine parts.

I realize that i am four years late, but i just had an idea to help catch flying parts.... put a one-gallon freezer bag around the part under test. cut a hole in each end to pass the ropes through so that the bag can't add any strength to the part under test (not that it would add meaningful strength). it probably won't stop some of the more energetic pops, but it should slow down the pieces enough that you don't have to hunt all over the shop for them.

I used to get my ass chewed for dropping these and stepping on rope. You all should do a rope test next.

This is awesome! One of my new favorite channels. I love climbing and breaking shit.

Yeah micro-fractures are def a sketchy ground, but thanks for the info!! and please put a plexiglass cover over your machine! :) MBS tested equipment can jump a lot. From my POW it is good practice to not use any gear after you dropped it from a wall. For instance I dropped a Photon Screw Lock from 400 feet, found it and retired. When I tested the carabiner got to 24 kN. So apparently no issues. I believe that what mfr are saying is that there is a very tiny chance you get micro-fractures after carabiners fall down. The thing is that as they categorised as PPE class 3 according to European regulations, hence protecting the user from death. So this is when even small chances lead to extra safety. In terms of fatigue as some other comments were saying be aware that fatigue in metals concerns loads that are generally much lower than MBS, but simply repeat them to thousands (sometimes million cycles) and they lead to breakage (classic example train axles). There are very interesting studies linked to some carabiners and fatigue, specially considering paragliding flight (search for DHV). Even with very low figures (100-150 kg) a carabiner might break after 100'000 cycles. Of course in climbing this is not really relevant, by the time your gear gets to 10'000 cycles it will look that bad that you might just wanna use it as a keychain.

Small imperfections may be points of corrosion entry. Possibly have some abused equipment stored in sub optimal conditions (left dirty and damp for a period of timed and repeat.

From what I remember the micro fracture thing started from a bad batch of biners from just one company back in the early 90's but who knows. Love your show

It does look like the lowest numbers came from the abused equipment. I will still use my known history equipment and keep the others for utility where I know I won't fall to my death even though I know that a triaxial load or a mis-aligned over a rock has a much more likely risk of failure. Great info and keep up the great work.

Please please !! Buy some Chinese branded carabiners and test them 🙏🏽🙏🏽

Lol the action shot edits were so stupid and I'm here for it

Might I ask why test 824 and 830 were disregarded in your conclusion? Those instances identify that the carabiners were compromised. The reason behind microfracture caution is that invisible damage could possibly compromise your gear, which I believe you have proven with your tests. All the new gear held to within 2% standard deviation from the mean while test 824 showed 5% less strength and test 830 showed 12% less strength. Thats a 33% chance your gear has been compromised and weakened from its original state.

Thanks for the testing and the mith-busting!

Kudos for not just tying them to a piece of string and whipping them around, so you don't have to bend over to pick them up constantly...

I imagine it's less likely that micro-fractures are the cause, but rather stress concentrators. Basically if you get enough dents in the wrong places you can artificially create a place where all the force gets dumped and it breaks faster. Imagine taking it and cutting a notch all the way around the shaft of the clip, what's what it can functionally do. It would explain why they broke in less consistent ways at less consistent forces. It's no longer breaking in the designed location at the designed force. It's breaking in the location dictated by where the stress is being concentrated. If it doesn't compromise the integrity enough, it breaks how it should. You may have even work hardened it a tiny bit or allowed for more plastic deformation in certain places that wouldn't normally get it. But if you get blemishes in just the right places you get significant failure differences. So it's more nuanced that does it cause a crack. It's how is the structural integrity affected by small dents where.

LMAO that smashing montage was incredible

was always curious about that but couldnt find actual tests so thanks

Very cool, just wanted to throw some ideas into the air for wearing out the carabiner in a more practical manner. I want to preface, you guys have an amazing set up to do these test and the method used for testing looked very consistent. I just want to add some ideas for further tests because I'm very curious myself. Prefacing these tests I want to give some insight on some of my thoughts. Throwing the carabiner on the ground would most likely result in compressive and shear strain. These forces will wear out products, however compressive and shear forces are not typically how materials break but still lead to structural degradation. Typically materials break from tensile strain/forces, which is how you guys mangled those carabiners for science with your pulleys. I think it would be really cool to come back to these tests and include another way to strain the carabiners with tension. Some ideas would lead climbing falls, or even some mad lad contraptions you guys can think of. I don't know if producing tensile strain on the carabiners would yield actual results, but I think it's worth a shot. Awesome video, and thanks for keeping us entertained (:

All that throwing and not one Hadouken gag.

This is not what I was learn from the past, surprised for the well building of those structure, good work.

Fatigue is way more dangerus than this dents from hitting surfaces. Because it is more like cold forging. It just keeps the internal cristallin struckture. But, fatigue can start often from such damages and slowly crack through the material.

I was once told by an industry professional (canopy your builder and trainer) that when microfractures were "officially" made a thing to look out for they x-rayed new steel carabineers, dropped them and x-rayed them again, and there were no fractuctures before dropping and some after. Break tests showed the ones with microfractures failing in a catastrophic manner. More recently someone x-rayed NEW aluminum carabineers and saw micro fractures there. Basically the aluminum ones develop microfractures in the forging process, so EVERY aluminum carabineers has microfractures, but aluminum, as a softer, less brittle metal, doesn't fail catastrophically as a result of microfractures the way steel does. If you drop steel from three feet to rock it's done, but aluminum is likely okay. (How okay would take far more comprehensive testing and larger sample size)

Why has nobody noted the slow pulling into a break is a different stress than a near instantaneous snap of a falling human? (Aka shear force)

I know in sailing and aircraft it's the corrosion that lives in the cracks that grows faster and unseen is what really makes it more fragile. Sure the nicks and cracks give stress some place to gather but the hitting corrosion that's the killer that makes the micro grow from not visible to visible. Give it a try and water and current to speed up time. Salt if you want to make it go really fast

Aluminum is sensitive to salt from sweat or the environment which can hugely increase fatigue by weakening and removing the hard oxide that keeps aluminum from rusting. Salt will wick into a microcrack. Still more likely to be a problem on a beach or a boat than a mountain.

I like Mammut carabiners.But they have some issue: some models have plastic pin under the spring,which lock the gate of carabiner.And this plastic can give away,and you can use your carabiner

This is good to know! It would be also great to see how minimal usage affects strength of biners. Like a few cycles of weighting/releasing load. I have noticed that most biners can be flexed a bit just by pulling apart with your hands. So that kind of usage can build up some fatigue in the aluminum. I'm curious how much?

I am a climber as well as an engineer. The biggest variable missing here imo is *time*. A single impact is not going to shatter a biner, and I'm sure Mammut makes extra sure of this during their testing. The real question is, after a few impacts, what happens as the carabiner gets weathered. If you load the carabiner repeatedly? Then leave it exposed to the elements. Allow it to slightly expand and contract with temperature changes. Etc. Basically simulate real climbing conditions. After many cycles of this I'm sure you would be able to measure some compromise in the material's integrity.

Did quick maths. If we count an average for LineScale data, we can see, that this might have a little impact. For Crag Wire Gate, we get around 2.48 percent less strength after tossing them around, and for Locking Carabiner we get about 7.12 percent less strength. Of course to have more accurate data, you should brake like couple hundred of carabiners with different types, but we all know it would be quite expensive to do it :D

sharp dents in aluminum, any metal really, cause stress risers. which is why changes in direction are radiused. Aluminum also work hardens and gets more brittle under mechanical deformation.

Micro fractures are a thing but you never checked if you have any cracks. Throwing them on the floor are not guaranteeing that you create one on the inside of the carabiner. You maybe created them on the outside but you should do a test over loading them until shape changes and after a day try a pull test again. All the best from japan

Great content, is it true a carabiner can’t be used if exposed to salt water. I heard it during Air assault school. We used non locking “snap link” carabiner.

You should test auto locking devices and see how many KN it can take before it slips or destroys the rope. IE pilot, Grigri, traxion, ATC in guide mode etc.

I can answer the results you should expect from this, you should see no big reduction in strenght this is because throwing them on the ground only cause minor frequencies into the metal. This aluminium is designed to withstand forces beyond 20kN. If you want to introduce microfractures the only way to get those is by tweaking the metal back and forth. And you need ultrasound to inspect for microfractures as it will resonate differently on weakened areas.

Would you guys consider doing any fall tests on rope stoppers like what they use in the Czech Republic? That stuff seems to sketchy, but the more I think about it, the less bad they seem.

A few years ago there were a few paraglider carabiners that broke. Kind of surprising considering that paraglider carabiners probably have a much easier life than climbing carabiners. I’m not sure if there was ever a study done on why they broke.

I thought the whole microfracture precaution was more about descending gear that heats and cools Repeatedly. especially if the cooling is fast like in a canyon situation on a dry abseil into a cold pool

This video was recommended to me and here are a few thoughts. I rarely comment on youtube videos but felt like I needed to make an exception here. This is not a good test of micro fractures. You have tested scratched up carabiners vs brand new, you have absolutely no way of knowing if these carabiners you threw at the floor have micro fractures, All this video has really shown is that there is little difference between scratched and unscratched carabiners. To say that you are testing the effect of micro fractures is completely misleading. Smashing carabiners against the floor will not ( is extremely unlikey) to create micro fractures in the material. Micro fractures exist as a result of repeated high loading. A good visual demonstration here to help understand micro fractures is to try and rip a sheet of paper by pulling in the same direction at either end, it is surprisingly difficult, adding a small tear into the top of the paper decreases how hard you would need to pull to rip the paper. In the context of aluminium weighting it and unweighting it repeatedly (cyclic loading) will tear at these micro fractures over time. A better test would be to do a break test on a carabiners that have been used for climbing for several years, or to test a carabiner that you had subjected to repeat on/off cyclic loading. Thank you for bringing up the issue of micro fractures though, many people are unaware of them and their possible effects.

Great info Can you test some of the amazon cheap climbing gear companies like GM Climbing and Xinda.

Still, that one carabiner that went 21.11 should be considered. I wouldn't put trashed carabiners into situatuions that could go over 20kN anymore.

I was always worried about micro fractures after a shock load more then bashing them. So do that test please, bring it fast to right b4 or right after the limit. Then do it till it breaks and see if that changes it.

I'm curious about a carabiner dropped between 20 and to a hundred feet. Also I'm curious about a stainless steel Rapide. Also if these carabiners/rapides were in a rope bag (so a little bit of cushion). This is canyoneering specific. I personally don't throw my carabiners but I will toss my rope and rope bag, but I've seen some who keep carabiners in the rope bag, and they toss the rope bag. Also to keep in mind, these are rapelling forces only.

I'm enjoying the trashing montage much more then I ever though I will

Trashing the carabiner that way crated the microfratures FROM WHICH THE CRACK WILL START, if the carabiner would undergo a long cyclical loading. Just starting the crack will not affect the resistance much, as you've shown, but that's not the problem with microfractures

Note to self: Throwing carabiners on the ground makes them stronger 😂

you gotta let water in those tiny breaks in the aluminum over long periods over time. i've seen it it bike parts. especially crank arms. cracks you can't see that have let water in over time that eventually fail and when they fail you can see the corrosion coming from the outside in along the invisible crack. after working on bikes and going into climbing i've always assumed that this could happen to carabiners. inspect your gear thoroughly, maybe even with a magnifying glass, why not?

I’m no scientist, or expert on micro fractures. I work heavy construction, every time I’ve done a heavy lift, 100 tons or more, they do a fluoroscope test on the equipment. So ya, micro fractures are a thing. Fractures propagate.

I don't really know anything about climbing gear but I do know microfracture is a something that can happen to aluminum. It's usually is caused when its bent slightly then returns to it original shape

micro fractures from repeated high loading will be in the most damaging places, ones from dropping will be in random places that are less loaded

I have some metolius mini wiregates that are rated for 22 (I think). They say on the side "For rock climbing and moutaineering use only" As if it is not rated for keychain and dog walking duties.

Can we get a cyclical loading test like if u used ur climbing carabiners for your long line

Ryan.... what happens if the carabiners are heated? for example for being hanged 50cm over a house heating sistem !! where they get heated then cold , heated then cold,. ... or in the car on a road trip where in the day they get heated then at night cold. for several days or months.

2:01 Dude Perfect carabiner edition.

Some thrown carabiners went below their guarantee strengths, so how does that prove no microfractures? I agree they were still good enough for use. Not considering the damaged gate.

I am a NDI Technician in San Francisco. I can inspect your aluminum carabiners for cracks if you'd be interested in finding cracks in any. In addition, I can make a video showing you it.

I always thought it only worth worrying about if the item fell from height. Like serious height and achieved terminal velocity. Alternatively you could put a microscope on it and look for the actual presence of micro cracks. Otherwise I’d bet on this non result.

Microfractures are definitely a real thing and not a myth. But it will take a great deal of force, than a person tossing them against the ground. Microfractures tend to occur from metal "fatigue", when a piece of metal is exposed to repeated stress, typically in opposite directions over a long period of time, like a a car leaf spring that flexes from an application of load, and then returns to true when the load is removed. The best case for existence of microfractures would be the tragic case of British very first passenger jets, Comet. Most people don't know but the British were the first to use Passenger jets with turbo fan engines after WW2, not Boeing. But the whole program was doomed when, one plane after another started to experience sudden rapid explosive decompression at 30,000 feet, in total 3 planes were lost and countless lives lost all because, no one understood how microfractures develop in the skin of an airplane after each cycle of pressurization, and depressurization. Its too long of a story for me to do it justice here, so I suggest you look it up if you are interested. Keep up the good work guys, everything I watch your videos i want to get back into climbing all over again, but its been over 10 years since I've last climbed, maybe I'll just stick to watching you guys for now.

What brand longsleeve are you wearing in the beginning? Looking for one exactly like that for climbing.

Ну теперь с уверенностью можно сказать, что карабины заявленную нагрузку держат и миф про микротрещины просто миф. Спасибо вам за ваши видео!

One of my thoughts on micro-fractures is that maybe it is a combination of the fracture over time, with the affects of oxidation crystallization acting like frost-wedging on rock.

Would love to see some cheap/non rated hardware store carabiners to shoe how even "strong looking" non rated carabiners are not enough, and you need actual rated ones

I wanna see expensive bd draws compared to the cheaper wire gate bd draws. In this video a lot of the biners are breaking at the nose and I know that on the more expensive bd draws there is no wire gate/nose. Are they really worth that extra coin?

So what you're saying is that if I (totally hypothetically...) dropped a carabiner from the top of my single pitch sport route - it's still ok to use?

Oh cool. Black Diamond's QC lab called, and said they've already done exhaustive, rigorous, scientific testing on all manner of gear. And have ruled that dropping gear doesn't harm it. And then 2007 and the Outdoor Safety Institute called, and said they've got published findings on this.

When I begun climbing I was told not to use biner that were found at the bootm of the cliffs because falls from high above would be bad for biners. So IMHO throwing biners to the ground is not really smashing enough. You would have to throw them at 220 km/H against a hard surface (to simulate a fall from high enough) and then we could consider them smashed. seriously, there are some serious metalurgists input here. And it looks like the myth originated from a misunderstanding/collapsing of issues done by non-specialist: myth origin: 1/ micro-fracture exist and are bad (Comet anyone ?) Premise True but the origin of the fracture in alumiium is repetive loading cycle (fatigue) 2/ biners hit bad develop micro-fractures premise False 3/ biners hit hard develop micro-frctures (Incorrect conclusion

"Raw aluminum, cool!" I can tell you are not easy to impress I assumed you would get at least one of them breaking at a higher load after you banged them up because my guess is that it de-stresses the metal a bit like peening. Sure, it is inconsistently applied and there are more highly abraded and surface roughened areas that can increase fatiguing, but in general a goodly amount of small impacts evenly distributed through a crystalline structure like a metal lattice should work out stresses like a thick fluid works out bubbles and make it more ideally compressed?

Your data set is way too small to make any kind of serious conclusion. Also I don't know if the carabiners reached terminal velocity when they were hitting the ground. The carabiners hitting different surfaces could also affect the results. My health is worth the expense of replacing a piece of compromised climbing equipment.

I think cyclic loading is what causes microfractures. Stressing and unstressing over and over causes micro fracturing.

Well, these things are supposed to perform above their rating, and you still managed to drop two of those below their rating just by banging them around. It's your life in the balance. One unlucky drop from high enough could be all it takes to perform way below the rating. Then you take a good fall and suddenly your carabiner... kaput.

A dude dropped 2 of my BD nuts from 60ft and refused to give them back because he claimed that they might have microfractures and needed to be thrown away. True story.

Microfractures are not a myth it is an issue that can happens in bolts and I've had to tap into a drill bit at work.

I think microfractures bécame more notorios on belay and rappeling devices as the rompe increpases the temperature, would wish that video

Anybody who follows the scientific method is a scientist! Reliable in my book.

I know shit ,but is it possible for it to work harden in a small way ? Causing stress fractures?

That beginning was very painful to watch

12:40 is the conclusion

My bro science brain says that with something metallic, especially as soft as aluminium, if you're throwing it on the ground and its getting dinged and nicked then enough of the force is being absorbed by the fkex of the metal that there's little to no actual fracturing, though they could form stress concentrations maybe? I feel like them being "stronger" afterwards is probably a result of work hardening. This said by someone with no experience with climbing or metallurgy or engineering or anything so dont quote me

I don't think you showed that it was a myth. 30% of the abused carabineers had seriously degraded failure strength. You might get more consistent results by putting them in a rock tumbler with some good jagged pieces of granite and running it for a few hours. Harbor Freight has cheap tumblers which ought to fit the bill.