Reaching Breaking Point: Materials, Stresses, & Toughness: Crash Course Engineering #18

Today we’re going to start thinking about materials that are used in engineering. We’ll look at mechanical properties of materials, stress-strain diagrams, elasticity and toughness, and describe other material properties like hardness, creep strength, and fatigue strength.
Crash Course Engineering is produced in association with PBS Digital Studios: • All PBS Digital Studio...
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RESOURCES:
writing.engr.psu.edu/uer/basse...
humanorigins.si.edu/evidence/b...
www.nasa.gov/topics/technolog...
www.graphene.manchester.ac.uk...
www.nde-ed.org/EducationResou...
www.azom.com/article.aspx?Art...
ispatguru.com/material-hardnes...
www.nde-ed.org/EducationResou...
books.google.co.uk/books?id=U...
www.twi-global.com/technical-...
www.merriam-webster.com/dicti...
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[@verdatum]

I can't put into words how much I love this. I'm a hobbyist blacksmith, and far too often in this realm we see these termed used far too loosely. This is because most blacksmiths haven't had the material engineering that evolved out of what the historical blacksmiths came to learn. Giving these words like strength, toughness, and hardness formal definitions makes them all so much more useful, but only to those who have taken the time to learn their proper formalized meanings. Videos like this, make that understanding so very much easier. As a teen, I tried to learn this from things like Modern Marvels on cable TV, and they would almost always get at least one critical aspect almost completely wrong.

[@Razes92]

As material engineer this episode makes me happy, thanks for spreading the knowledge

[@RangerRuby]

This just shows that no matter how strong something is, it always has a breaking point. I liked how you went into so much detail and taught me something new! Thanks for this video! I found it very interesting and I can't wait for the next video! DFTBA!

[@HolyKoolaid]

In other words, jet fuel doesn't have to "melt steel beams." It just has to decrease its point of failure under stress.

[@gio2341]

jew fuel cant melt steel memes

[@AcRPAINTBALL]

hahahahhahaha

[@copyRtest1]

Jet fuel doesn't cause two 110 story, billion dollar skyscrapers to explode into powder and implode at freefall speed into a subterranean lake of literal molten metal though. Building 7 too...

[@USSAnimeNCC-]

lol

[@shitrowersdo]

CopyRtest1 - You're right it doesn't! What it actually causes a billion dollar skyscraper to collapse is heat! By itself jet fuel doesn't collapse a building, but add in a jet crashing into it at flight speed reducing the structural stability of steel beams, and heat those steel beams up real hot, and the beams fail. Therefore, the beams not maintaining structural integrity at extreme heat while still under large compressive stress is what causes a building to fall, and jet fuel just helped the beams get nice and hot. Once the stress on the hot beams is high enough, the weight of the rest of the building on top of the hot beams causes the beams to "buckle" and give out, you then have that mass of building accelerating and falling into the rest of the unheated beams, and since Force is equal to mass times acceleration, the acceleration of the top of the falling building is several several times greater than before it was falling! As the top falls down, the material it falls into is unable to keep its structural integrity, and a cascading failure occurs. Now spreading misinformation about events which directly lead to the deaths of many is uncool, luckily now you know have an expanded picture of why crashing jet planes into buildings can cause them to fall down. Building 7 was taken out by aliens, and potentially pressure waves caused by collapsing buildings along with being an older building that may not have been as structurally sound as the others, but mostly aliens.

[@fastfoodisgross]

It's funny. I'm in college for ChemE and you guys always seem to release videos as I'm taking each course (just started a semester with Material Sciences)

[@noalear]

YES! I am dealing with this at work constantly. It felt like you were talking to me specifically. That really help me understand.

[@moonscapes11]

Thank you for inspiring a lot of people, including myself. You and your friends are the reason I decided to film and edit videos for myself, as some sort of memory. I am very grateful for that and many laughs you have brought to us over this!

[@Pfhorrest]

Fun fact: all substances are either metals or non-metals, and either organic or inorganic, and while there are no organic metals, there are inorganic non-metals, and those are the ceramics, including glass. Polymers, of course, are organic; so between them, metal, and ceramics, you've basically just said that "for now, the materials engineers work with are [exhaustive list of all possible materials]".

[@dragonbrown1494]

Your soothing voice really makes these lessons more engaging than it needs to be

[@ArunGoyal2007]

Very well presented. I did the test of communicability. In the whole length of 11 mins, I had to rewind only once to understand the term. Very well packaged and presented. Congratulations.

[@jaredbourne4201]

She actually convinces me to do a course civil engineer

[@oyahfftlisawsome]

As a Materials Engineering student, I'll have to start sharing this video around whenever people ask me "so, what's that?"

[@Simon-ow6td]

Hey, cool! I had missed that cc-engineering was a thing! Now I have some great videos to watch :)

[@LTDoge-dm3jr]

This channel is debatable in the topic of killing it as an act of mercy. Ever since they stopped making philosophy videos. The only reason I subscribed. It truly has been a fun ride. I learned so much about others and about myself. Thanks and goodbye

[@MarkBlease]

Material failure was my favorite part of my material science course last semester.

[@jagadeeshvikramc2516]

So Good.. Awesome Description and Vivid Explanation.. 👏👌👍❤️💐

[@vernyeoh]

5:58-6:06 “But as you apply even more stress... the material will begin to deform and stretch along its cross-section as well as its length” Just want to suggest adding in some detail here as the above sentence seems a bit ambiguous. Even in the elastic region of the stress-strain graph, all (normal) materials do experience deformation span/transverse-wise, and not just lengthwise before the yield point (see Poisson effect and/or Poisson’s ratio). In the elastic region, this effect is uniform across the material, as the cross-section area deforms uniformly across the entire length. At the yield point and beyond, this deformation begins to be non-uniform and is localized instead - hence the specimen necking/getting thinner in the middle before failure occurs there. (Also, I feel that defining the yield point as being the point beyond which the material can no longer return to its original shape to be a clearer explanation than the above). To summarize then, perhaps it would be better to phrase the above as “the material will begin to deform and stretch *non-uniformly* along its cross-section as well as its length” - or something along this tune? Still, thanks for summarizing a semester’s worth of introductory materials engineering so well! Wanted to add this to prevent any misconceptions of when transverse deformation occurs.

[@Nacur]

Uhul!!!! So much love for materials engineering

[@bizzysevenseventhree8498]

Love this series

[@ioan_jivan]

great episode

[@Petch85]

Most of what I do in 11 min video :-) You should have show a SN curve. But it was a nice intro to mechanical engenerring.

[@hn9518]

Yay! Stress-stain curves!

[@evanrigel954]

i heard somewhere that there was a minor fire onboard a few days before the ship sank. it was put out, but the heat changes made the hull more brittle. anyone know if that's true?

[@rei_cirith]

Year 2 Engineering stress course in a nutshell, right here. =D

[@tanqs789]

As a Material scientist, thanks.

[@thinker8682]

By the way, it was all Chemical Engineering from episode #7 to #17.

[@gmsherry1953]

I thought I knew this stuff (though it HAS been 46 years since I took a structures class in architecture school), but at 7:26, you say low carbon steel has a lower modulus of elasticity even though the slope on the stress-strain graph is identical to high carbon steel. It looks to me like what low carbon steel has is a lower elastic limit or yield point. Am I wrong?

[@zhubajie6940]

I had hoped you'd would have mentioned transition temperatures for them resulting in such things in the Space Shuttle Challenger failure and possibly an important variable in the Titanic sinking.

[@frithiofeN]

What a coinsedens my course on uni today had the exakt same subject c:

[@mikey10006]

The entirety of this engineering crash course(minus fluids) is taught in my a level classes like from 1-14 and from here to the semiconductor video is a level physics engineering or sumn lol

[@ArunGoyal2007]

Of coure, I am a good student too who is greatly interested in the subject, that makes the test a bit biased , nonetheless, my absorption rate is a a good indicator of the the communication strength of the video.

[@rparl]

Concrete has a high compressive and a low tensile strength. That's the reason for pre- and post-stressed concrete.

[@nacoran]

In the harmonica world there are metal reeds. Historically they used bell brass. Today there are two main materials... bronze-phosphor and stainless steel (not sure what grade but it's magnetic but still good with moisture). There is a debate over which last longer. People fall into both camps, but I've noticed that the people who say steel lasts long self-describe themselves as hard players. My guess is that the stainless is staying under the fatigue stress levels with gentle players but more vulnerable at higher levels. I've read that under certain levels steel (and titanium) can undergo nearly infinite cycles without breaking. I also know when they are retuning reeds a lot of customizers prefer to polish to remove metal rather than just scratch the reeds because they are worried that scratches will create weak points that could lead to reed failure. (At $40 a pop for a harmonica, with 20 reeds per harp, with 12 harps in your set people worry about details like this!)

[@Heavy2deep]

Thank you

[@HolisticApproach]

Be tough even though there so much pressure nowadays.

[@jnzkngs]

Why do I keep seeing ads for extenzometers in my social media feed?

[@JEOGRAPHYSongs]

Engineering is the creative application of science, mathematical methods, and empirical evidence to the innovation, design, construction, operation and maintenance of structures, machines, materials, devices, systems, processes, and organizations. The discipline of engineering encompasses a broad range of more specialized fields of engineering, each with a more specific emphasis on particular areas of applied mathematics, applied science, and types of application.

[@BlueyMcPhluey]

this is six months of material science class right here

[@dan1204hc]

You can work and research materials, stresses and toughness following the career of Civil or Mechanical Engineering.

[@ncooty]

"Lenth"? Is this a new dimension? Is it similar to length?

[@tkidtyoy]

How is creep useful in concrete?

[@FalbertForester]

Interesting that they used the Titanic as an example, instead of that old classic, the Tacoma Narrows Bridge (1940).

[@niambbii3708]

Titanic is popular UK history so we often use that example because people know it.

[@isabellao5336]

the failure of the Tacoma Narrows Bridge (1940) is more commonly associated with resonant frequency rather than material failure due to impacts which is probably why it wasn't used as an example as it could confuse some people

[@engibear6392]

*Stress? Strain? Fatigue? Now we're talking!*

[@JV-the-Tossh]

Minor pedantry here, but... "Ep-SI-lon"? I am pretty sure it is supposed to be "EP-si-lon". Second syllable is said like "see", not "sigh". Minor linguist complain over. I do apologize.

[@satansamael666]

Will we go through social engineering???

[@rubymoon9565]

this video recommended by *bender rodriguez*

[@666evilgizmo666]

Your reason the Titantic went down was incorrect. It had nothing to do with the strength of the steel used. It had everything to do with the design of the ship.

[@drunkestrick4476]

Creeper, aww man

[@loganl3746]

I wonder how hard it was for her to say "math" instead of "maths" as a British person

[@PhilipHuang234]

Creeper

[@fox971000]

I wanted to see the Mohr Circle :’(

[@lazytv4318]

I was looking for this too but maybe it might be a little too "advanced" for something that is a just a summarized intro...oh well...

[@BlueyMcPhluey]

We just learned about Mohr Circles a couple of weeks ago and currently it seems very useless haha

[@oldcowbb]

we need mohr!

[@TheLemonyLimey]

MSE major, anyone?

[@tanqs789]

hi.

[@tanqs789]

can i have some of your cementite?

[@alexanderlewis189]

Ello

[@StarlordStavanger]

She is such a goddess

[@thepokemonchannel7797]

Titanic broke because of overconfidence 💩

[@QuantumPolagnus]

Titanic broke because too many of its internal, watertight compartments had been compromised by sideswiping the iceberg. If it had hit the iceberg head-on, as the animation indicated, it probably wouldn't have sunk. It was actually built to be able to float with four out of fifteen of those compartments flooded, but five of them were breached by the iceberg.

[@ArnyBoy]

Who's here cause they missed this in Crash Course Physics?

[@unleashingpotential-psycho9433]

Minecraft monsters are scary T_T

[@Melecie]

UNLEASHING POTENTIAL - PSYCHOLOGY VIDEOS no don’t

[@USSAnimeNCC-]

Herobrine want to meet you lol

[@okaydudejm]

11th

[@Pfhorrest]

"The letter ep-Cylon". Oh meh GAH Brits are weird.

[@brianhack5806]

epsilon. ;)

[@ruthwiksreenath3653]

Second

[@Gilder-von-Schattenkreuz]

Wow. What a needlessly convoluted and complicated way to explain this. Too Technical with too little Explanation. I actually learned such stuff and yet aside from terminology I hardly was able to comprehend any of what you said and basicly had to remember things from what I learned myself to realize what your Talking about.... In Essence your Explaining what the Words mean but give it absolutely Zero Practical Knowledge to go with. For an Actual Engineer this might be understandable. But for those of us which are not Educated in Engineering especially even if we do have education in this field due to other Areas of Expertise this is really really hard to grasp. One example. Your actually using a Steel Beam as your first Example and then actually Show a Bridge. And you Explain that Materials will Bend and Break if a certain amount of Force is applied. Yet one of the most Importand Examples on Materials Qualities and one of the Reasons why Steel is such a Widely used Material for Bridges remains entirely unmentioned. One of the First things we Learned was about Permanent Deformation and Reversive Deformation (sorry if its not the correct Terminology in English I didnt learn it in English ^^) You are actually later on mentioning the effect of continues Stress and that smaller amounts of stress might reduce the breaking Point of the Material over time. Yet again in your explanation it basicly sounds like Material once it starts deforming is automaticly permanently damaged and will reduce its breaking point. Leaving out the Property of Materials being able to withstand certain repeated stress levels by deforming and then returning to Original form after the stress lets off. Or maybe you actually mentioned it but I didnt understand it :P Anyways. I think you should Redo this Video or maybe do a Second Video on it. I somehow dont think that many people without extensive prior knowledge in this field will actually be able to make sense of this right now ^^

[@Mazda1080]

It was victoria not titanic. Lie in the history needs to be changed.

[@donnetube73]

I watched as she is just plan the best looking women alive....

[@user-or1em1qf1t]

Firstttt✨

[@nad2040]

Titanic had damaged metal from burning. And there were no binoculars

[@RebSike]

The fire myth is complete BS. The "burn mark where the coal bunker was" in those photos was over 70 ft forward of where the fire was, over the mail room, and it wouldn't matter if the lookouts had binoculars or not because they only used the binoculars to identify things AFTER they saw them. A navy engineer commented that no modern ship would've survived that impact not severely damaged.

[@Johnjo85]

FIRST!!!!!!!!

[@I.AM.WALKER.]

Making tools 2.5 million years ago. Not! 250 k maybe.

[@justiceforsethrichwwg1wga160]

I’d tap