New try! I got demonetized and age restricted with the first upload, KZbin thought that "oho" was bad word during the first 15 seconds? So let's try without that! Happy new year again to everyone!
@AbsoluuttinenTotuus2 жыл бұрын
Very Rasscist of KZbin. Not good.
@FinnishedThirdMusic2 жыл бұрын
No onhan oho nyt aika törkeä sana
@Jason-Voorhees5412 жыл бұрын
Guten Rutsch ins neue Jahr
@SomeRandomPiggo2 жыл бұрын
@@AbsoluuttinenTotuus racist?
@AbsoluuttinenTotuus2 жыл бұрын
@@SomeRandomPiggo raascist against Finns
@milesmccollough5507 Жыл бұрын
“that was really stupid” is a hefty understatement for most of the things on this channel. never change or stop, you wonderful finns.
@velowelder6333 Жыл бұрын
An infrared camera would be very interesting to see just how quickly things get hot under pressure.
@pilotreg Жыл бұрын
you're right
@_sandy_ Жыл бұрын
underrated comment
@flan740 Жыл бұрын
this
@tankl.jackson3481 Жыл бұрын
It's illegal to destroy money. I have turned it into the police.
@bardgold4553 Жыл бұрын
@@tankl.jackson3481 yea sure the police are gonna care. Ever been to disneyland? You put a coin in and it stamps it with a design? The police dont give a shit.
@ryimscaith1593 Жыл бұрын
I'm a machinist that makes the tools for powdered metal compaction presses. They operate anywhere between 100-1000 tons of force. Videos like this demonstrate why my tolerances are +/- .0001 inch for dimensions. (.00254mm) In effect, it's either perfect, or scrap, because if we mess up, things like in this video happen.
@ToBeIsWasWere Жыл бұрын
hecking americans man.... just use 0.0025mm or 0.001mm or so, doing any type of machining or engineering work in imperial (or metric that has to be converted to inches) is just mental. Way too many issues like differing international standards, eventual errors in the conversion or just confusion (looking at you 25 million dollar lost sattelite or what it was that went down because of mixed use of imperial and metric)
@npip99 Жыл бұрын
@@ToBeIsWasWere The satellite went down because of _mixed_ use. Not one particular system being "mental". It's also easy for the same mistake to happen within a system as well (Reporting mm instead of cm).
@ryimscaith1593 Жыл бұрын
@@ToBeIsWasWere Just seen your reply. I only referenced metric for those that don't easily think in inches. I can easily work in either, and know well that mixing the two doesn't work well. Many customers will try to do so, because a lot of college trained engineers are stupid, but we send those blueprints back to be corrected, or we don't take the job. Also, while I'm am an American, you can take that attitude and stuff it in your sauerkraut. Been around the world while in the military and for my profession. I can tell you for free that stupid is everywhere and knows no country borders.
@charlesmayberry2825 Жыл бұрын
@@ryimscaith1593 Also as a machinist, I easily work in both, but never at the same time. Mixing them is asking for disaster, especially with for instance the NC machine I ran frequently, to go between you had to toggle it manually in the controller, and then load another program programmed for that section, then toggle back, too much room for an error, loading the wrong program, forgetting to load the other, or forgetting to change it to metric control at the stop, all of these reasons were why we would not do it. Also I did a LOT of manual machining, why not do it in metric? because the machine was made in imperial, and with no DRO, going on indicators and the scales on the machine, if it's made in imperial, I work imperial only on those machines. Tobias does have a point in conversion errors, however the shops I worked in never accepted a print that didn't match what the machine was set up to do, and say if they wanted a part off a manual machine and the print was metric, we sent the customer the print back, THEY can convert it, then as long as we make it to the print, it's not my problem if they converted it incorrectly. Machinist 101, make it like the drawing, so when they complain, you made exactly what they asked for, if it wasn't what they wanted that is a them problem, and they are still going to be paying the agreed price.
@davidaugustofc2574 Жыл бұрын
@@npip99 mm instead of cm I've never seen happening, one is 10 times bigger than the other
@helyferrer933 Жыл бұрын
Beautiful! I never tire of seeing bearings exploding. It is a work of art in slow motion! all those parts dancing in space with sparks and lights... I just love it!
@Watthead802 жыл бұрын
The chisel and the coins has to be the most satisfying thing to watch. I love how they stay stacked and just go shooting off to the side.
@Watthead802 жыл бұрын
@John Alpha I used to do that too, but never managed to find them afterwards. They always seemed to get sent flying off, that or I was just not looking hard enough. Had the attention span of a gnat back then.
@dannycarlow82042 жыл бұрын
@@jimboSleeeeiiice I thought so too but it's not molten metal. There's a hole in the top of the hammer and you can see. Plus the tiny pieces left on the base would have cooled and not still been red. It's whatever was helping the handle stay connected to the head of the hammer.
@haroldhenderson28242 жыл бұрын
The different failure modes! Stressed fiber (paper), Ductile (most metals), compressive failure of ceramic/rock.
@haroldhenderson28242 жыл бұрын
@John Alpha Not stacked, but placed here and there. Rough wheels tend to pick them up for a few revolutions (3 to 20 feet)
@SiegeTF2 жыл бұрын
Hope theybwere foreign coins, or it could be a serious crime!
@rabooey Жыл бұрын
In a million years I would have never thought that layers of paper under extreme pressure would explode/shatter like that. Astounding.
@happynihilist2573 Жыл бұрын
It's actually pretty obvious that's what would happen when you understand the forces at play It's the same principle behind a volcanic eruption: lots of pressure builds up in one place, eventually it's enough to overpower the forces kipping it at bay (the surface rock for the volcano, the tensile strength for the book) witch results results in all that pressure begins released BOOM
@RndmBad Жыл бұрын
I was shocked at first too, then I remembered there was such a thing as dust explosions, where enough combustible particles collect in a tight area can explode. And that's without any kind of external pressure like using a hydraulic press.
@highdownmartin Жыл бұрын
@@RndmBad that’s very different, it’s an incredibly rapid burn.
@GuninGames Жыл бұрын
That's called tension, Paper surprisingly has a high tension resistance, If you simply pull a piece of paper on opposite ends it will not tear, or will give a very hard snap if pulled hard enough, Because the press is pushing down on the paper, it wants to slide out from under the press but is evening out the energy in all directions at once and eventually, well, you can see what happens
@pretzelbomb6105 Жыл бұрын
Imagine the same situation occurring on a block of wood,since that’s effectively what a compressed book is. That paper didn’t shatter, it splintered.
@StephenRWilliams2 жыл бұрын
Some people wonder why tyrants always say books are so dangerous. Maybe this is why.
@fartpluswetone80772 жыл бұрын
With enough force and potential energy, anything is possible!
@wes45782 жыл бұрын
imagine getting shot by a fucking book lol
@briansimcoe91192 жыл бұрын
@@wes4578 "Finnish him!"
@Tipicall2 жыл бұрын
@@briansimcoe9119 finish* 🤓
@briansimcoe91192 жыл бұрын
@@Tipicall Finnish. 🇫🇮
@lazkennedy Жыл бұрын
There's something unusually satisfying and fascinating about seeing a stack of coins smushed into a a giant mega coin. Also makes the stories of how my uncle would trick arcade machines back in the day by using pennies he flattened out with a hammer make more sense.
@jackieparmz Жыл бұрын
8 years later and this is still my favorite ASMR channel.
@kathryndavidson5056 Жыл бұрын
I am simply amazed by how deeply satisfying this is!
@EngineerHarris2 жыл бұрын
Therapist: Would you say your job involves high pressure and stressful work? HPC: Yes
@Squeeeez Жыл бұрын
Very dynamic environment
@Onsvaltti Жыл бұрын
Jes* (finnish accent)
@asteroidrules2 жыл бұрын
It's particularly impressive how, even on the high speed camera, the broken pieces fly so fast. There's so much force being imparted on them.
@justkev1044 Жыл бұрын
All the tens of thousands of kg on stuff under one kg
@seffard Жыл бұрын
This high speed camera isnt fast enough.
@jarekferenc1149 Жыл бұрын
More interestingly, how this force is converted to elastic energy, and how the elastic energy is instantly converted to kinetic energy and to heat upon rupture.
@VITAS874 Жыл бұрын
a paper can cut you very well if you didn't know...
@AdverseCity2103 Жыл бұрын
The Slo Mo Guys did it... kzbin.info/www/bejne/Z3KclqOGf9eUntEsi=-Q34PVzRyUrC9-l6
@Leffe1922 жыл бұрын
Really one of my favourites of all time is 12:20 when Lauri sounds genuinely surprised and happy that the safety glasses worked as intended.
@madamerosario2 жыл бұрын
"This is like, educational!" too cute.
@victorlaurent37 Жыл бұрын
It really is educational. Imagine paying about 1 dollar to keep your vision.
@TehNoobiness Жыл бұрын
It's kind of amazing that the safety glasses were only _scratched_ after taking a chunk of a drill bit moving at an appreciable fraction of the speed of sound
@oilfan9445 Жыл бұрын
Could you try using an infrared camera to see how hot the pressure points get on an object? I think that’d be neat to see.
@tomdragon3881 Жыл бұрын
This is a great idea
@MunkeeMedia Жыл бұрын
i love that there is an endless amount of things to press... and on top that multiplied by the methods.. .this is ENDLESS content
@user-ok4pk2mp3e2 жыл бұрын
It's so interesting to see how much energy can be stored in objects under pressure. At the point when the object explodes, nearly all of the energy that is released is coming from the tension from within the object. Really cool physics.
@sevenspec Жыл бұрын
You should see what happens with radioactive materials 😲
@markvandoren33872 жыл бұрын
Absolutely amazing how much energy is released when compressing paper. You guys are crazy.
@AL-SH Жыл бұрын
E=MC²
@pretzelbomb6105 Жыл бұрын
@@AL-SH Wrong equation. You’re looking for F=ma. Force equals Mass times Acceleration. The force the press exerts onto the target is equal to its mass (heavy) times its acceleration (considerable). The targets deform until they can’t and then start absorbing that energy until they *suddenly* can’t.
@vh4990 Жыл бұрын
nuclear reaction paper 🤯
@Lcshell Жыл бұрын
Paper was crazy, how bout that knife though!!😮
@TransoceanicOutreach Жыл бұрын
The amount released is the same as the amount you put in. In this case, 70 tons of force.
@nigel9002 жыл бұрын
You know, putting a column of post it notes under extreme pressure like that is an excellent demonstration of what happens in deep mines, where the colossal pressure of overburden can trigger a burst from the mine shaft wall or pillar.
@HubertofLiege2 жыл бұрын
You should use something other than post it notes in your mine. Lol
@dinamush1342 Жыл бұрын
@@HubertofLiege smh imagine using post it notes to support a cave. Cardboard seems like such a better alternative
@IcanBePsycho Жыл бұрын
This is so satisfying watching this. Thanks for posting ✌️
@metairieman55 Жыл бұрын
Absolutely useless but most entertaining channel on KZbin!!! I could watch this for hours . . . and sometimes do!
@TheSchultinator Жыл бұрын
"I have the best worst idea" is such an accurate statement for so many situations
@caelan53012 жыл бұрын
Every time I watch this guy, I remember why this is the best hydraulic press channel. It really all comes down to the accent, it makes these videos way funnier and he knows it.
@Super-lucky-7777 Жыл бұрын
Not guud 🤭 I like when he says this.
@BlackMasterRoshi Жыл бұрын
sounds like marco repairs coffee time for talk english
@hectorolea9665 Жыл бұрын
Where is he from?
@caelan5301 Жыл бұрын
@@hectorolea9665 pretty sure he's Finnish
@hectorolea9665 Жыл бұрын
Aaah! Thats who he sounded like. ISMO, the comedian. He sounded like someone i had heard before
@DanGoodShotHD2 жыл бұрын
All the years I've watched your vids and I've never thought of how much of a beating that sudden break in pressure must be on the press.
@NOT_NativeEN_Speaker Жыл бұрын
That gentleman's laugh is just diabolic :) Another amazing video 👍Paper rulezzz!
@stickykitty Жыл бұрын
The moment he said at 0:44 "....... Alright.... that's not .. good" I died of laughter 😂
@Brothernumber32 жыл бұрын
I love the fact that when you boil it down to basic terms, If you squeeze something hard enough, it'll explode.
@dapple-drawings Жыл бұрын
Yes
@kibe2134 Жыл бұрын
That's how stars work.
@Andoryuuu Жыл бұрын
@@kibe2134 pretty much exactly this.
@frequentuser360 Жыл бұрын
@@kibe2134 Extreme density is something I really struggle to understand and your comment has clarified a number of questions bouncing around my head. Thanks!
@deksea Жыл бұрын
Under those conditions, the answer is yes and no. Elastic properties of the material play a big part.
@dog4mike2 жыл бұрын
After watching this channel for a couple years or so, I can honestly say I have no idea what a hydraulic press would be used for other than this. UPDATE: While I appreciate all the replies explaining what a hydraulic press is used for, I perhaps should point out that my comment was a joke. I know what it's used for. My comment was a joke referring to the seemingly infinite uses for a press that aren't actually the intended use. I realise sarcasm is not conveyed easily through text, hope this clears it up.
@yourmother27792 жыл бұрын
Smashburgers
@jennifergray5499 Жыл бұрын
Haaaa
@readmyusernamecauseitssoreally Жыл бұрын
Mostly garbage compaction
@Gurziak Жыл бұрын
A machine like this would be used in a manufacturing process where parts are quite literally press fit together when the matching pieces are machined in tight tolerance of each other within .001 of a inch or tighter. Think like bearing housings and stuff like that.
@FreeHat_ Жыл бұрын
To kill the terminator
@TheSauciest2 жыл бұрын
The cheeky smile from the paper roll before it explodes is perfect
@mlpreiss Жыл бұрын
"Now that was really stupid!" Lol! Best commentary ever by a KZbin creator!
@Godric_71 Жыл бұрын
Dude: Hey. I have an idea. Let's just explode everything.
@subjectt.change65992 жыл бұрын
This is so unaccountably satisfying. Most channels get boring after a while, but this? Nope. Still wonderful.
@xanderopal7367 Жыл бұрын
These are so fun to watch. And helped with being more safe in the workshop using a much smaller press by knowing how it can go very bad!
@Ducks887 Жыл бұрын
At 4:40 it sounds like you gained Minecraft experience points.
@maximilianmaier3950 Жыл бұрын
"Let's explode the book and the knife in one go" A few moments later: "Ok, that was really stupid" lol
@theodorelueker5057 Жыл бұрын
Great video. I love the work you are doing. I am so glad you got this reuploaded.
@nickwolf8052 жыл бұрын
LOVE THE DESTRUCTION!!! Eager for more in 2023
@kristofevarsson69032 жыл бұрын
3:16 "Hey! I have the best worst idea!" -- famous last words
@teknologyguy56382 жыл бұрын
The safety glasses melon videos were among my favorites this year.
@JWolf180 Жыл бұрын
Woww those bearings at the end were amazing beautiful! 🤩 That's the best thing I've seen on YT for a while.
@LeafMobbMusic Жыл бұрын
These videos are SO cool, seriously!
@ljcool10042 жыл бұрын
That high speed camera action at the end was insane! Happy new year
@Stijn-x8p2 жыл бұрын
Amazing as always! *Happy new year!*
@christopherrobin81342 жыл бұрын
1:27 You’re finally awake
@usernamwdrama Жыл бұрын
Awesome stuff, thanks for the entertainment.
@mezmerizer02662 жыл бұрын
The coins getting snipped down the center are always my favorite. The sound, and the visual is just exciting to the senses.
@WoodworkerDon2 жыл бұрын
Hyvää uutta vuotta. Happy New Year!
@bghoody56652 жыл бұрын
The slow-mo of the stack of coins being cut in half sounded like something out of a fantasy movie. And the prefragmented ball bearing, well, all I can say is "Great shot, kid. That was one in a million."
@davidmctimm777 Жыл бұрын
Neat! Commentary even better!
@engscott78 Жыл бұрын
Pretty much everything will explode if compressed hard enough is what I learned. What a rad video. Wild watching paper explode!
@davidvickery18582 жыл бұрын
Thank yous for being so fun with the hydrolic press. I've really enjoyed watching.
@jonkirkwood4692 жыл бұрын
I don't know why, but I found the failure of the large bolt threads to be highly entertaining. I retired from an industry where we were more concerned with bolt elongation. The drill bit was informative. Thankfully, the melon lived.
@ikeman57742 жыл бұрын
This is so awesome. I've worked with hydraulic presses, but not at these pressures. Total destruction. I love it.
@BuddWolf Жыл бұрын
Great video footage. Best of luck 🍀👍🏻🇺🇸
@patmack2871 Жыл бұрын
Dude this channel rocks, I just found it
@newrepublic75392 жыл бұрын
Came across this video in my feed so I'm a new viewer to your channel. This video reminds me of when I was in high school my theatre tech buddies and I would do similar things with the trash compactor on campus. I enjoyed this so much, what a great video!
@acikacika2 жыл бұрын
How come you and SlowMo guys never did a colab, this is gold
@FreedomOnALeash17762 жыл бұрын
I love how he said, "Eh it's okay, it'll sort itself out." 😂
@rafezetter8003 Жыл бұрын
The rocks experiment, how they go all crumbly (friable is the correct term) is the same as what happens to the rocks at an impact site of a meteor - the impact force is so high it literally powders the rocks, then compacts them again so they look like rocks, but they can be crumbled in your hands - I've seen it at the Arizona Crater. All the "rocks" within and near the impact crater are like this.
@iai2354 Жыл бұрын
the satisfaction of watching things get destroyed is unmatched
@halaboly89152 жыл бұрын
2:25, I unconsciously blew on my phone screen thinking I'd blow the glass powder off 🤦🏻♂️
@briansimcoe91192 жыл бұрын
It would be interesting if you used a laser thermometer to find out how much that chilly mallet heated up as it compressed.
@alexanderkonczal39082 жыл бұрын
Never ceasing to amuse and entertain. Glad you're still doing this.
@TBolt1 Жыл бұрын
12:25 “yea hey this is like educational.” 😂 Subscribe button clicked. ✅
@summerfire477510 ай бұрын
Can’t help but to laugh so hard! It’s simple videos like these that brings me joy
@c1h2r3i4s569872 жыл бұрын
2:50 Never knew He did this but he made a machine of childhood dreams, a knife that cuts just by going straight down, so satisfying
@matthewchavez76682 жыл бұрын
Awesome recap video! Love your videos!
@SkyeDavis-wn8hh Жыл бұрын
I wanna see Slow Mo Guys collab with you guys!
@Tchild2 Жыл бұрын
The best part was how much joy and laughter this caused. LOL.
@j-schnab63382 жыл бұрын
This was so satisfying. The frozen hammer, the coins being cut and both of the bearings were the best! The last bearing was AMAZING on high speed.
@robertlantz22062 жыл бұрын
It's amazing to see the different ways thing react to extreme pressure. Love the slow motion shots. 👍👍👍👍👍
@Teknokoleji2 жыл бұрын
The video auditions for the year 2022 were very good, it was a video that I watched with great pleasure, and we look forward to the continuation of your successes in 2023.
@smishdws Жыл бұрын
hydraulic press channel is a treasure to humanity
@jaredklein6927 Жыл бұрын
The most amazing part to me is how successful a channel is just for smashing stuff with a press. One more thing I wish I’d thought of.
@prague54192 жыл бұрын
Everytime I see you put paper or bearings on the press I instinctively hide under my desk. HA HA. Love you guys!
@barrygravett69372 жыл бұрын
Happy new year to both of you !
@TundeEszlari2 жыл бұрын
Perfect video.
@jaimedelgado7529 Жыл бұрын
Superb video. Idk why I love the paper explosions. Stay classy guys !
@Jaesiane Жыл бұрын
We need a collaboration with The Slow Mo Guys ASAP!!
@senmetwo422 жыл бұрын
This was like a firework show for new years. What fun!
@ghost809192 жыл бұрын
9:20 so that's how they got the original death star shot
@jesseshort82 жыл бұрын
"hey, that's pretty God damned good" happy New year guys!! 🥂
@R3TROSKULL2 жыл бұрын
wut
@shanghunter76972 жыл бұрын
God had nothing to do with this but t.y. for mentioning my best friend's name !! WUT
@caleb3175 Жыл бұрын
This song has hit me harder than anything from mainstream music EVER has. Thank you
@mattmalyj7964 Жыл бұрын
0:32is actually a slow motion animation of my head exploding from stress
@paulr.49682 жыл бұрын
Funny and educational❗️
@erickelly87042 жыл бұрын
That’s crazy going to need protection for camera too 😂 for now on start saying we are behind protective measures 🤣🤣🤣
@indianexpress46132 жыл бұрын
😂😂😂😂😂😂
@officialfusionnetworks Жыл бұрын
1:22 why does this look like a real life death animation, except without post process
@michaelhanson57732 жыл бұрын
The thing that just seems so crazy to me is how this press can destroy pretty much anything but yet the pieces used in the press like the chisel and other ends never seem to get damaged...
@Mister_Clean Жыл бұрын
Some heat treated alloys are strong as hell
@tricursor2481 Жыл бұрын
You can find older videos where he talks about how he has to remake the pressing tool pretty much every video. Definitely on videos with really hard things like ball bearings. It looks similar because it's a tool shop, he can make the press head himself and they're easily replaced.
@stankythecat6735 Жыл бұрын
I’d love to see a thermal camera view of the sudden temp change
@lnr122412 жыл бұрын
At 12:00 where did all those colors come from with that drill bit? ? That was nuts
@NoClarity Жыл бұрын
Play-doh was used to hold the drill bit in the press
@lnr12241 Жыл бұрын
@Nic lol that's funny. And genius. The many uses for play-doh
@richardruiz6972 Жыл бұрын
OMG this is such a cool channel !
@MISTERLeSkid Жыл бұрын
It would be really interesting if you could set-up a cheap (since you'll probably only get one or two uses out of them before they're blown-up) $10-15 infrared kitchen thermometer in the shot and aim it at whatever you're squishing. I'd love to see the reading shoot from room temperature to 500-600 degrees simply from adding mechanical force to various materials, metals especially. Does paper get hot from compression? It would be neat to see, anyway.
@charlesmayberry2825 Жыл бұрын
Everything gets hot when compressed, you're adding energy to the system. However, I agree 100% I want to see how much, and how much it differs per material, because it will vary drastically. So Very interested in that lol
@marvelaturraz54052 жыл бұрын
That is so fascinating to watch but at the same time is so stressful! (And scary, frankly). Because those energy releases can be absolutely DEADLY. Are you sure that you have enough protection? I really hope that no one ever gets injured when making these videos.
@JCGver2 жыл бұрын
2:00 I bet if he was recording audio we would have learned some new Finnish swear words.
@WoodworkerDon2 жыл бұрын
Whenever Lauri says "...not good." that is a guarantee that it will be good.
@mikejohnson5900 Жыл бұрын
Lol...I like the Watermelon with the safety glasses. And the 1/2 book sliding off the cutting board. Good job!
@robpolaris7272 Жыл бұрын
The sparks on that ball bearing were insane!
@TurpInTexas2 жыл бұрын
Lol! I use Alexa to control most of the lights in my house and shop, but sometimes when I tell her to turn on or turn off the BENCH lights, I feel she misunderstands me like I said another word that sounds much like BENCH and she ignores me. By the way, my favorite episodes involved compressing the paper, who would have ever thought a stack of paper would explode so violently? Lol! May you and your family remain safe, happy, and enjoy a prosperous New Year! Your friends in Texas!
@skrimper2 жыл бұрын
Is it "Wench"? Mine does the same thing lol, thinks I'm insulting it
@TurpInTexas2 жыл бұрын
@@skrimper I think it thinks I am saying "bitch", because it replies with that high-low tone like it heard me but the command was bad, so its won't act on it. If say slower and enunciate clearly, it works almost every time.
@tracybowling11562 жыл бұрын
I've seen these all already. But they're too fun to pass up another look.
@B3Band2 жыл бұрын
Yeah, that's kind of how end of year compilations work.
@Terrell2119 Жыл бұрын
I don't know why I can't stop watching things get crushed into oblivion.
@brandonmelendez19412 жыл бұрын
This just goes to show how strong paper really is…
@Vagabond_Etranger Жыл бұрын
As part of safety procedure if you're in an earthquake in a building, they tell you to lie next to stacks of phone book/papers, instead of under a desk.
@Repugnantone Жыл бұрын
See? It really does beat rock!
@danielfranco1345 Жыл бұрын
dilo en español jajaja
@easternadventures9978 Жыл бұрын
The string was the real MVP
@Tristan_eCola Жыл бұрын
@@Vagabond_Etranger realistically who’s going to have high enough multiple stacks of books just lying around though. Unless you work in a printing factory or library it seems quite unlikely. Desks on the other hand, much more prominent.
@machdaddy6451 Жыл бұрын
Gives a whole new meaning to "destructive testing"