Pratica di Shadowing: Carbon Fiber - The Material Of The Future? - Impara a parlare inglese con i video

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Throughout history, our biggest leaps in technology have occurred as a result of new materials becoming available.

I've shown you how it took humankind centuries to master iron and steel, culminating in the explosion and growth during the industrial revolution.

How the accidental discovery of age hardening allowed aluminium to take humans into the stratosphere in droves, and how silicon forms the backbone of this age of information.

But today we're going to discover the next great leap in material science, carbon fiber reinforced plastics.

Carbon fiber and its even more futuristic brother,

carbon nanotubes, have been touted as the next great innovation that will allow humans to build amazing structures that were once unimaginable.

Elon Musk recently revealed an enormous carbon fiber reinforced plastic cryogenic fuel tank,

the largest fuel tank that has ever been created for spaceflight building spaceships of this size is not an easy task.

The larger the spaceship, the more fuel you need to escape the Earth's gravity.

The more fuel you need, the bigger the fuel tank needs to be to hold it, which just adds more mass to the rocket.

Carbon fiber reinforced plastics provided a new way to keep the weight down

while maintaining the strength needed to withstand the internal pressures.

But building a structure like this from carbon fiber is no easy task.

This is the sort of material that if a crash landed on Earth just 70 years ago, it would have been a completely alien object and we are still learning a lot about its mechanics.

The fact SpaceX have created a structure this size out of carbon fiber reinforced plastics

that has already been tested at two-thirds of its bursting pressure is astounding by itself.

But we've yet to see whether it can resist the blistering cold temperatures of the liquid fuels without cracking and leaking, and do it repeatedly.

After all, the whole point of SpaceX rockets is to be reusable.

Building a cryotank out of composite materials is without a doubt the most difficult part of building a spaceship of this size.

Don't believe me?

Listen to the man himself say it.

This is really the hardest part of the spaceship.

The other pieces we have a pretty good handle on, but this was the trickiest one, so we want to tackle it first.

Nevertheless, the material will be pivotal in reducing the weight of our craft enough to escape the gravity prison

that has kept humans as a single planet species.

Even though we are still learning a lot about the material, carbon fibers by themselves are not as new as you may think.

The first carbon fibers were produced by Thomas Edison and Joseph Swan for use as filaments in their new electric incandescent lamps.

The carbon fibers they created were produced by carbonizing plant threads like cotton, wood and bamboo.

This material did not have the tensile strength of today's carbon fibers, but they allowed Edison and Swan to replace the expensive platinum filaments being used earlier.

The carbon bamboo filaments Edison developed lasted up to 1,200 hours

and they were the norm for 10 years until tungsten filaments replaced them.

Not much thought was put into carbon fibre as a structural material until the late 1950s when the Union Carbide Corporation,

a company that manufactured light bulb filaments, began investigating replacements for tungsten filaments.

They started using rayon, an artificial cellulose based material popular as a cheap alternative to silk

and cotton as the base ingredient for carbon fibres.

This was a breakthrough moment for the start of the modern carbon fibre era, as the resulting materials showed potential as a structural material.

Researchers all over the world took notice

and just a month later the Japanese Industrial Research Institute began investigating how to make their own fibres from polyacrylonitrile, or PAN for short.

The majority of today's carbon fibre is produced with PAN, even though it is an expensive byproduct of oil production.

It yields a fibre with a much higher percentage of carbon than rayon and is easier to manufacture.

Dr Shindo created long strands of this PAN material

which he stabilized by first heat heating it to around 250 degrees for up to 2 hours.

This rearranges the chemical bonding to create a thermally stable ladder bonding.

These fibres were then heated again to around 1000 degrees in the absence of oxygen, which expels the non-carbon atoms in the material,

leaving tightly bonded carbon atoms arranged mostly in the direction of the fibre.

This material was both heat and chemical resistant.

It had fantastic tensile strength and didn't rust.

Specialised industries like aerospace immediately saw its potential to help spacecraft break the grip of Earth's gravity.

And when Gabe Brewer won the Teheyo, Club Masters Golf Tournament, in 1972, using a carbon fibre composite shaft, the material captured the world's attention too.

Sporting goods manufacturers all over the world began creating carbon fibre products.

Golf clubs, tennis rackets and racing bikes started to be made with the cheaper off-spec fibres

that the aerospace industry could not use.

Despite its high price, demand for the material kept growing and by 1980, 1000 metric tons were being produced a year.

But it was still a notoriously difficult material to work with and many still doubted its ability as a structural material.

During the development of the McLaren MP4-1, one sceptical engineer is said to have picked up a piece of carbon fibre composite just like this

and easily snapped it in half, declaring that the material was too weak and brittle to be used for the ambitious carbon fibre composite monocoque.

But he was breaking the material across the fibres.

If he had attempted to break it along the fibres, he would have had serious difficulty.

You see, carbon fibre is made from these tiny thin fibres.

This is a picture showing the size difference between a carbon fibre and a human hair.

The carbon fibre is a smaller one.

These tiny fibres by themselves can't be used as a material.

We first have to bind these long strands of fibre together with a plastic resin.

Otherwise they are just a flimsy fabric that can't hold any load other than tension.

Here you can see a solid piece of carbon fibre, where the fibres are surrounded by white resin.

But this technique causes some problems for engineers when designing a product with this material, because the plastic is weaker than the fibres.

This is a unidirectional layer of carbon fiber held together with resin.

If we pull it this way along the fibers it has fantastic strength

because the fibers are in the same direction as the load and thus can resist it.

But if we pull it this way there is no continuous run of fibers to resist the force.

Instead the resin matrix gets pulled apart and the fibers add very little strength to the material.

To combat this, engineers will layer the fibers on top of each other.

Here we have a 0 degree layer on top of a 90 degree layer.

So the material properties are the same in those directions.

But now the 45 degree direction is weaker.

We can keep adding more layers until we have similar stiffness in all directions, but eventually the thickness of the material will become too great.

We reach another problem when we remember there is nothing but the resin matrix holding these layers together.

And sometimes that fails, and we get delamination of the layers.

This is why you often see the carbon fibers woven into a fabric like this, but again woven fabrics can only be so thick.

We also need to worry about the drapeability of the material, as these fabrics need to be shaped over molds, and a very thick material like this can make that job very difficult.

These issues create a whole lot of work for engineers working with composites, but with experience we've learned to use these unique material characteristics to our advantage.

The designers of the MP4-1 managed to create such a strong monocoque with the material, that when the car did crash, it silenced many of its doubters.

We can tailor the fiber directions to optimize the material properties.

Here we perform the tensile tests on a tiny piece of

carbon fiber composite with fibers only in the direction of the force,

creating an incredibly rigid structure that barely deformed through the test and managed to hold 5.3 tons before braking.

But stiffness like that is not always desired.

For example, in the event of a crash you want your car to crumble

and deform to absorb as much energy as possible.

And so composite noses of F1 cars are designed to fragment into millions of tiny bits

and this helps absorb energy and decelerate the car more slowly.

Pressure vessels like the Dreamliner fuselage are wrapped in layer after layer of resin soaked carbon fibre by a robot

that places it in the exact right position, making the structure perfect for withstanding internal pressure.

One of the big problems when building a structure this big would composite is

that they need to be placed in an autoclave to get the best quality material.

An autoclave applies heat and pressure to the material to set the resin

and forces the air and other voids that weaken the material out of the resin during the curing process.

The autoclave Boeing uses for the Dreamliner is massive

and there isn't an autoclave in the world big enough to fit the tank SpaceX created.

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It's hard to know how they did it, but they almost certainly used an automated tape placement robot, like the one Boeing used to create their own smaller cryotanks,

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which can cure the resin with a laser as it lays the pre-preg carbon fibre tape down.

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But it's very hard to create quality parts with this method, as the pressure of the autoclave is essential for removing voids in the resin.

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And this is such a huge concern for composite manufacturers, the parts are often scanned with ultrasound technology to check that the resin has cured with a tolerable amount of microvoids.

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This machine sends ultrasound into the part through a jet of water and detects the voids in the material.

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These voids are an even bigger concern for this application, because the biggest problem for the material is cryogenic fuel leaking through microcracks in voids.

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Looking at the outside of the tank, I would say with a fair bit of certainty

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that the the tank was made in two halves that could fit in an autoclave, and was then riveted and welded together, which I would imagine will be removed for the final version,

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as this just creates weakness in the structure.

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But this is all guesswork.

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B-b-b-b-b-b-b-breakin news!

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Yeah.

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Haha.

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So while I was making this video, pictures were posted to the SpaceX subreddit by user DeathcogUnit, showing the remains of the CryoTank after being tested.

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It failed exactly where I said it was going to fail, but SpaceX have yet to make a formal announcement about the results of this new test.

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This does not mean failure of the project, we test things to learn more and it's fantastic that SpaceX are pushing the boundaries of what is possible.

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I still have so many questions about how this thing was made, which just makes it more frustrating

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that all the questions being asked in the Q&A session after the big reveal were so stupid.

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This advancement, if we can make it work, will be the most significant leap in rocket technology we've seen in recent memory.

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Boeing stated that their cryo tank provided a 40% weight savings over traditional aluminium fuel tanks.

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That is going to allow us to launch larger vehicles into orbit, reach further into our solar system and hopefully, not in the too distant future,

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it will help humans become a multi-planetary species.

122

that the site is finally live at www.realengineering.net and it's looking great thanks to Squarespace.

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Thank you Squarespace for helping Real Engineering exist both here on YouTube and on our beautiful new website.

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If you'd like to follow our progress as we build this site, please sign up to the newsletter on the site.

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And thank you to all my viewers and Patreon supporters too.

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I'm close to making my first hire for this channel to make more of the content that you love.

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If you'd like to support Real Engineering, please consider supporting us on Patreon or maybe even buy the new Real Engineering t-shirt

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which is available as a $20 reward on Patreon or over on dftba.com.

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If you'd like to see more from me, the links for my Patreon, Facebook, Twitter and Instagram accounts are in the description.

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Vocabolario e note di pronuncia per questa lezione

Questa lezione di conversazione di livello C1 si basa sul video “Carbon Fiber - The Material Of The Future?”. Le parole che ritornano più spesso: material, carbon, fibre, fiber, resin. Questo video contiene 133 frasi e 2201 parole da ripetere con lo shadowing. Il parlato dura 11:40. Chi parla va veloce, circa 189 parole al minuto: aspettati suoni legati e ridotti. Solo il 77% delle parole rientra nelle 3.000 più comuni dell’inglese, quindi il lessico è impegnativo.

Vocaboli chiave di questo video

Le 15 parole più avanzate del video, con pronuncia e significato:

Parola	Pronuncia	Significato
fibre sostantivo	/ˈfaɪ.bə(ɹ)/	fibra
resin sostantivo	/ˈɹɛzɪn/	resina
filament sostantivo	/ˈfɪləmənt/	filamento
void aggettivo	/vɔɪd/	vuoto
reinforce verbo	/ˌɹiː.ɪnˈfɔːs/	rinforzare
spaceship sostantivo		nave spaziale, astronave
cryogenic aggettivo	/ˌkɹaɪoʊˈd͡ʒɛnɪk/	criogenico
deform verbo	/dəˈfɔɹm/	deformare
monocoque sostantivo		monoscocca, monoguscio
stiffness sostantivo		rigidezza, rigidità
tungsten sostantivo	/ˈtʌŋstən/	tungsteno, wolframio
ultrasound sostantivo	/ʌl.tɹə.saʊnd/	ultrasuono
weave verbo	/wiːv/	tessere, intrecciare
bamboo sostantivo	/bæmˈbu/	bambù
strand sostantivo	/ˈstɹænd/	filo

I phrasal verb che sentirai

Parola	Significato
pick up verbo	tirare su, sollevare

La grammatica di questo video

Le strutture che chi parla usa di più, con le parole esatte del video:

Struttura	Nel video
Present perfect have/has + participio passato — un’azione passata che conta ancora adesso	have occurred · I've shown · have been touted
Forma passiva be + participio passato — conta ciò che accade, non chi lo fa	have been touted · been created · been tested

Pronuncia a cui fare attenzione

Chi parla usa 14 contrazioni e forme ridotte, come we've, you'd, can't. Pronunciale nella forma breve, così come le senti.

I suoni “th”: withstand /wɪðˈstænd/, thickness /ˈθɪknəs/, breakthrough /ˈbɹeɪk.θɹuː/
I suoni “sh” e “zh”: delamination /diːˌlæmɪˈneɪʃən/, shaft /ˈʃɑːft/, ambitious /æmˈbɪʃ.əs/, speculation /ˌspɛk.jəˈleɪ.ʃən/
Parole lunghe — attenzione all’accento: aluminium /ˌæl.(j)uˈmɪn.i.əm/, decelerate /diːˈsɛləɹeɪt/, delamination /diːˌlæmɪˈneɪʃən/, planetary /ˈplænɪˌtɛəri/, intuitive /ɪnˈtjuːɪtɪv/

I suoni difficili per chi parla italiano:

Consonante finale — senza aggiungere una vocale dopo: composite /kəmˈpɑzɪt/, autoclave /ˈɔt.əˌkleɪv/, filament /ˈfɪləmənt/, void /vɔɪd/, reinforce /ˌɹiː.ɪnˈfɔːs/
/æ/ — più aperta della “e”: fabric /ˈfæb.ɹɪk/, bamboo /bæmˈbu/, strand /ˈstɹænd/, atom /ˈætəm/, aluminium /ˌæl.(j)uˈmɪn.i.əm/

Come esercitarsi con questo video

Ascolta tutto il video una volta senza parlare e annota le parole che non conosci.
Inizia a velocità 0,75×, fai shadowing frase per frase e torna alla velocità normale quando diventa facile.
Registrati e confronta con l’originale, facendo attenzione a parole come fibre, resin, filament.

Cos'è la tecnica dello Shadowing?

Shadowing è una tecnica di apprendimento delle lingue supportata da studi scientifici, originariamente sviluppata per la formazione dei traduttori professionisti e resa popolare dal poliglotta Dr. Alexander Arguelles. Il metodo è semplice ma potente: ascolti un audio in inglese di madrelingua e lo ripeti immediatamente ad alta voce — come un'ombra che segue il parlante con un ritardo di solo 1–2 secondi. A differenza dell'ascolto passivo o degli esercizi di grammatica, lo shadowing costringe il tuo cervello e i muscoli della bocca a elaborare e riprodurre simultaneamente i modelli di discorso reale. La ricerca dimostra che migliora significativamente la precisione della pronuncia, l'intonazione, il ritmo, il discorso connesso, la comprensione dell'ascolto e la fluidità del parlato — rendendolo uno dei metodi più efficaci per la preparazione alla prova di speaking dell'IELTS e per la comunicazione reale in inglese.

Tecnica dello shadowing: leggi la guida completa passo dopo passo →

Pratica di Shadowing: Carbon Fiber - The Material Of The Future? - Impara a parlare inglese con i video

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