Shadowing Practice: Material Properties 101 - Learn English Speaking with Video

Les maken...
1
This video is going to be a bit different to my usual videos, but I want to talk about material properties and the words we use to describe them.
2
This is information you are going to need to fully understand future videos.
3
By the end of this video, I want you to understand 6 keywords that we use to describe materials.
4
These are stiff, strong, ductile, brittle, tough and hard.
5
With these words, you will be able to describe pretty much any material
6
and better understand why certain materials are used in different applications.
7
More technical videos like this will be uploaded to my second channel from now on, which you can subscribe to by following this link.
8
I'll try and back up the technical stuff with interesting real-world examples.
9
First we are going to learn what a tensile test is.
10
A tensile test is a fundamental test in material mechanics.
11
It's performed by pulling a sample of material apart until failure, while measuring the force and displacement.
12
It provides us with something called a stress strain curve, which tells us a lot about the material's reactions to forces.
13
In this scenario, the stress is defined by the force applied to the test sample, divided by the cross-sectional area.
14
This gives us units of newtons per meter squared, which you may recognize as the metric unit for pressure, Pascals.
15
Stress goes on the y-axis.
16
Strain describes how much deformation has occurred with that applied force, and it is found by dividing the change in length by the original length.
17
This is placed on the x-axis.
18
Let's watch this test again and see what information we can get from the stress strain graph.
19
As the stress rises, the material begins to deform.
20
This initial linear region is elastic deformation, That means if we remove the force, the material will regain its original shape.
21
Think of how a rubber band can deform hugely and still come back to its original shape.
22
The end of this linear elastic deformation is marked by the yield point.
23
From here out, any additional stress will cause permanent deformation.
24
This is called plastic deformation.
25
The stress continues to rise until it hits the ultimate tensile strength point.
26
This is the ultimate strength of the material, the most stress it can handle.
27
From here, less stress is needed as the material begins to decrease in cross section, which you can see happening here.
28
This is called necking.
29
This continues until the material fractures.
30
We can get a lot of really useful information from this graph.
31
The first is Young's modulus, otherwise known as the elastic modulus.
32
This describes how stiff the material is, and it is obtained by finding the slope of this linear region.
33
A steeper slope means a stiffer material.
34
For example, a high carbon steel may look like this, whereas a flexible material with the low Young's modulus, like rubber, would look like this.
35
This graph is not to scale, but it should give you an idea of how this information is represented.
36
Young's modulus is one of the most used properties in engineering, as we can use it to predict deflection in a huge range of scenarios.
37
Yield strength and ultimate tensile strength are two other important properties.
38
An engineer will divide the yield or ultimate strength by the safety factor to achieve the max allowable stress, which is used to influence the design of the product.
39
Usually engineers will aim to keep the max possible stress well below failure, but safety factors differ between industries.
40
So we've seen a stiff material and a flexible material.
41
Now let's look at a material in between.
42
This material can be described as tuff and ductile.
43
Tuff simply means the material can absorb a lot of energy without breaking.
44
The area under the graph here defines how much energy is absorbed.
45
Ductile means it deforms under pressure.
46
The two previous materials could also be considered ductile.
47
Springsteel is a tough and ductile material with a high yield strength which is why it is used in springs.
48
Springs need to absorb energy without permanently deforming.
49
The opposite of ductile is brittle.
50
A brittle material is a material that breaks with very little deformation.
51
Glass, ceramics and cast iron all fall into this category.
52
You can actually tell if a material is brittle or ductile by examining the fracture surface after they have broken.
53
A ductile material will have this characteristic cup and cone fracture surface, whereas brittle fractures have granular flat looking fracture surfaces.
54
Some materials can go from ductile to brittle when their temperatures are lowered.
55
This was actually a massive problem during World War 2 with the Liberty ship.
56
Several Several of these ships literally broke in half with no warning, including the SS John P.
57
Gaines, which broke in half in the frigid waters of the Bering Sea.
58
It was later discovered that the grade of steel being used became brittle at lower temperatures.
59
This problem was made worse by the stress concentration at the hatches, which you learned about in my first video, Why are plane windows round?
60
This embrittlement is also thought to have contributed to the fracture of the titanic's hull.
61
The final material property I want to talk about is hardness.
62
It is directly related to the stiffness and yield strength of the material, but it is used to describe how difficult it is to dent, scratch and abrade materials.
63
One way this material property is measured is with the Rockwell hardness test.
64
This test involves three steps.
65
First a minor load is applied to the material by an indenter.
66
This establishes a zero point.
67
For the second step, a major load is then added, which indents the material.
68
And for the final step, the major load is removed, while maintaining the initial load.
69
The difference in depth between the first and third step is then used to calculate the hardness of the material.
70
Diamond is a very hard material, which is why it is used in cutting tools.
71
One of the fantastic properties of steel is its ability to be heat treated, to have its hardness tailored in different areas.
72
For example, with swords you want your cutting edge to be hard but the core of the blade to be ductile.
73
This means the sword can bend under pressure without breaking, while the cutting edge can resist damage.
74
As always, thanks for watching.
75
I wouldn't have the opportunity to make videos like this without sponsors like Lumart.
76
Lumart is a new way to get college done quickly, from the university or college you choose for a lot less money.
77
I was lucky enough to get an education in Ireland for pretty much free, but this is not a luxury many people have.
78
In the US, the cost of getting a higher degree from a university is prohibitively expensive.
79
And the Lumerit Scholar program is out to change that.
80
Whether you are aspiring to go to college, or you are already there, Lumerit can allow you to complete up to 3 years of college for $4,000 or less per year,
81
and allow you to take classes from anywhere in the world.
82
So how does it work?
83
A Lumerit counselor will help you plan out your college path, getting credits from schools that are guaranteed to transfer to your target school.
84
Go to lumertscholar.com forward slash realengineering to see how much you can save with Lumert Scholar.
85
They will email you and give you a personalized consultation to help you save thousands on your education.

Woordenschat en spreektips bij deze les

Deze spreekles op niveau C1 is gebaseerd op de video “Material Properties 101”. Deze woorden komen het vaakst terug: material, stress, ductile, brittle, strength. Deze video bevat 85 zinnen en 1264 woorden om na te spreken. Het gesproken deel duurt 6:06. De spreker praat snel, ongeveer 207 woorden per minuut, dus reken op verbonden en ingeslikte klanken. 82% van de woorden hoort bij de 3.000 meest gebruikte Engelse woorden; de rest kun je beter vooraf bekijken.

Belangrijke woorden in deze video

De 15 moeilijkste woorden uit de video, met uitspraak en betekenis:

WoordUitspraakBetekenis
distress zelfstandig naamwoord/dɪˈstɹɛs/druk, stress
brittle bijvoeglijk naamwoord/ˈbɹɪtəl/bros, broos
deformation zelfstandig naamwoord/ˌdɛfəˈmeɪʃən/vervorming
fracture zelfstandig naamwoord/ˈfɹæk.t͡ʃʰəː/breuk, fractuur
hardness zelfstandig naamwoord/ˈhɑɹdnəs/hardheid
stiff bijvoeglijk naamwoord/stɪf/rigide, stug
graph zelfstandig naamwoord/ɡɹæf/grafiek
elastic bijvoeglijk naamwoord/ə-/elastieken
absorb werkwoord/æbˈsɔɹb/absorberen, (in zich) opnemen
tuff zelfstandig naamwoord/tʌf/tufsteen
slope zelfstandig naamwoord/sloʊp/helling
axis zelfstandig naamwoord/ˈæksɪs/as
abrade werkwoord/əˈbɹeɪd/schuren, afschuren
aspire werkwoord/əˈspaɪɚ/ambiëren, nastreven
embrittlement zelfstandig naamwoord/ɛmˈbɹɪtl̩mənt/verbrossing

Phrasal verbs die je zult horen

WoordBetekenis
back up werkwoordteruggaan

Grammatica in deze video

De structuren die de spreker het meest gebruikt, met de exacte woorden uit de video:

StructuurIn de video
Lijdende vorm be + voltooid deelwoord — het gaat om wat er gebeurt, niet om wie het doetwill be uploaded · is defined · is found
Present perfect have/has + voltooid deelwoord — iets uit het verleden dat nu nog telthas occurred · we've seen · have broken
Betrekkelijke bijzinnen who / which + zin — extra informatie over een persoon of dingstress, which is · strength which is · material, which is

Uitspraak om op te letten

De spreker gebruikt 3 samentrekkingen en verkorte vormen, zoals I'll, we've, wouldn't. Spreek ze kort uit, zoals je ze hoort.

  • De klanken “sh” en “zh”: deformation /ˌdɛfəˈmeɪʃən/, deflection /dəˈflɛkʃən/, sectional /ˈsɛkʃənəl/, consultation /ˌkɑnsəlˈteɪʃən/
  • Lange woorden — let op de klemtoon: deformation /ˌdɛfəˈmeɪʃən/, allowable /əˈlaʊ.əbəl/, personalize /ˈpɜː.sə.nə.laɪz/, characteristic /ˌkæɹ(ə)ktəˈɹɪstɪk/, consultation /ˌkɑnsəlˈteɪʃən/

Klanken die Nederlandstaligen lastig vinden:

  • Stemhebbende eindmedeklinker — /b/, /d/, /g/, /z/, /v/ niet verscherpen: absorb /æbˈsɔɹb/, abrade /əˈbɹeɪd/, frigid /ˈfɹɪd͡ʒɪd/, keyword /ˈkiː.wɜːd/, personalize /ˈpɜː.sə.nə.laɪz/
  • /æ/ — opener dan de Nederlandse “e”: fracture /ˈfɹæk.t͡ʃʰəː/, graph /ɡɹæf/, absorb /æbˈsɔɹb/, axis /ˈæksɪs/, granular /ˈɡɹæn.jə.lə(ɹ)/
  • /g/ — een harde plofklank, geen Nederlandse “g”: graph /ɡɹæf/, granular /ˈɡɹæn.jə.lə(ɹ)/, regain /ɹiːˈɡeɪn/

Zo oefen je met deze video

  1. Luister de hele video één keer zonder te spreken en noteer de woorden die je niet kent.
  2. Begin op 0,75× snelheid, spreek zin voor zin na en ga terug naar normale snelheid zodra het makkelijk gaat.
  3. Neem jezelf op en vergelijk met het origineel; let daarbij op woorden als distress, brittle, deformation.

Wat is de Shadowing-techniek?

Shadowing is een wetenschappelijk onderbouwde taalleermethode die oorspronkelijk is ontwikkeld voor professionele tolkentraining en gepopulariseerd door polyglot Dr. Alexander Arguelles. De methode is eenvoudig maar krachtig: je luistert naar native Engelse audio en herhaalt het onmiddellijk hardop — als een schaduw die de spreker volgt met slechts 1–2 seconden vertraging. In tegenstelling tot passief luisteren of grammaticadrills, dwingt shadowing je hersenen en mondspieren om echte spraakpatronen tegelijkertijd te verwerken en te reproduceren. Onderzoek toont aan dat het de uitspraaknauwkeurigheid, intonatie, ritme, verbonden spraak, luisterbegrip en spreekvaardigheid aanzienlijk verbetert — waardoor het een van de meest effectieve methoden is voor IELTS Speaking-voorbereiding en echte Engelse communicatie.

Shadowing-techniek: lees de volledige stap-voor-stap-gids →