跟读练习: What is Materials Engineering? - 通过YouTube学习英语口语
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Materials engineering is about designing,
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Materials engineering is about designing,
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processing, testing, and discovering materials, mainly solids.
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It's about analyzing the structure,
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properties, performance, and processing of materials and objects.
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In fact, if you do a Google search for materials engineering right now,
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you'll see this come up.
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And this basically says that all four of these things are connected,
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and by changing one, like the structure of a material,
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you change everything else.
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But let's first start with careers,
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like what would a materials engineer be doing or be needed for?
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Well, like I said in our aerospace video,
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aircrafts traveling at supersonic speeds are subject to
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so much friction from the air molecules that the aircraft can be heated to several hundred degrees Fahrenheit.
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The materials engineer might have to figure out or design the best material to use that can handle these conditions.
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Materials engineers are very important when it comes to cars.
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Did you know cars are designed to crumple when they are in a crash?
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They are made to have that accordion-like response and it saves lives.
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The cars crumple to absorb energy from the crash and they need the right material and structure to do this.
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If the car was extremely tough and no damage was done in a crash,
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all that energy would be transferred to the driver.
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The frame of the car may have harder metals at the top compared to the bottom
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because of how that will transfer energy from a crash away from a driver.
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How a car will be impacted in a crash is kind of predictable because that's how engineers design them,
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and a huge part of this is picking the right materials with the right properties.
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And on that topic, materials engineers deal a lot with fracture and how components fail.
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So you could work in a failure analysis lab where you have broken parts
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that can range from jet engines to computer parts and have to figure out what went wrong,
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and it's really about looking at the structure and material itself.
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The materials engineer who wrote this video with me had a
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job in a failure analysis lab where he had to look at the landing gear of a plane.
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But not shown here, the landing gear had a huge crack around it which almost broke it during landing.
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So he had to use a microscope and analyze the microstructure of the landing gear.
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This is a micrometer scale picture but tells us a lot.
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At this scale you can actually see where the crack originated from and how it physically propagated through the structure.
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The crack isn't shown here,
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but you'll learn how to analyze these in school.
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And guess what?
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Just like with the car,
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landing gear is designed to fail like this.
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The material and structure is designed so that if it failed,
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it wouldn't just snap.
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It would crack along a certain path so that during landing,
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even though there was a crack,
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the plane could still make it through the runway.
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So a materials engineer could also design how a structure will fail if and when it does.
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Then based on the failure analysis results,
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we can design even better landing gear and various other structures.
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Or maybe if a computer part failed,
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you're not going to do circuit analysis like an electrical engineer would,
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but you may be looking for a soldering issue where there's a connection problem
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and a component came loose from the circuit board.
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So again, you'd have to analyze this on a micro scale using a microscope and determine what happened and why.
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They also have to deal with corrosion,
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which is a big field for materials engineers,
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and you can even take elective classes on this in college.
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Corrosion is destructive to metal,
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so any pipes that carry some fluid will be subject to corrosion and need to be designed properly.
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Whether it's pipes that carry water to and from our houses,
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ones for oil, ones in our cars, and so on.
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Or various marine technologies like submarines need to be designed not to corrode from all the interaction with saltwater.
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Planes also need to account for this, and there's many more.
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And different environments these are subject to,
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like fresh water, salt water,
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oil, etc., cause for different types of considerations when designing them.
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Materials engineers need to take preventive measures to pick the right material to account for all this.
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You could work on biomaterials,
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which is something biomedical engineers take classes on as well.
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But biomaterials are used for constructing artificial organs or to replace bone or tissue,
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and these materials need to interact well with the human body and not cause harm.
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For example, there are hydrogels that are needed to repair damaged heart tissues.
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This incorporates biology and is something you could take an elective class on as well,
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or you could see in grad school if it interests you.
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You could work on making superconductors,
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which are materials that have no resistance to electron flow,
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like no heat or other form of energy is given off,
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unlike your electronics which get hot as you use them.
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And superconductors can be used for high speed digital circuits,
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particle detectors, trains that use magnetic levitation and don't make contact with the ground, and so on.
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They can also work on materials processing and manufacturing.
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Materials engineering isn't just about analyzing properties of materials and how to use them,
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but also better ways to manufacture these materials,
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like with the fabrication of semiconductors that are used in our electronics.
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Electrical engineers may do circuit analysis with these,
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but how those components are made is done by other types of engineers, including materials.
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Or you could work on the study of carefully rearranging atoms and molecules to form new structures that have better mechanical,
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electrical, and magnetic properties for a material.
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This is also known as nanotechnology.
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The way that atoms are arranged are what gives the materials a lot of their properties.
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It's why some things break when we drop them,
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and why other things stretch when we pull on them.
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If we can manipulate the arrangement of atoms,
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then we can change the object's properties and how it behaves.
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We can use this to create solar panels that can absorb energy much better,
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all the way to making glasses that won't break when being dropped,
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but there are so many more applications.
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Materials engineers could make clothes that don't smell bad after use,
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tires that grip the road better,
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stronger tennis rackets, and the list goes on.
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But now let's see what you can expect in college and kind of zoom in a little more on these materials.
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So you're going to cover the four main classes of materials which are metals,
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ceramics, polymers or plastics, and composites.
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And although you learn a lot about everything,
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there's a big focus on metals.
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Now when it comes to all these materials,
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big things we care about that you'll learn are the mechanical properties,
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electrical properties, thermal properties, as well as the atomic structures.
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Mechanical properties include hardness, ductility,
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or an object's ability to deform when being pulled,
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brittleness, where a material is brittle if you pull on it and it breaks without much deformation.
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So if you have a material and you pull it,
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eventually it will break.
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If it's brittle, it will just snap.
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Glass would be an example of this.
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But if the material is ductile,
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it will actually be elongated and deformed before totally snapping,
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and certain types of steel would be an example of this.
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In school, you're going to learn how to analyze certain graphs,
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which have stress or force over area,
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versus deformation or strain, like how far it's been stretched.
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Then they'll give you some curve,
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and you have to understand it.
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This shows that if you pull an object very hard,
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it only stretches a little.
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So you know this is a stiff material,
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versus a more flexible one,
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which might look like this,
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like for a rubber band.
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And there'd be more to these curves you'd have to understand,
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like its fracture point, ultimate strength,
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what the slope of that initial line means,
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and so on that can tell you more things like how brittle it is, and so on.
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And every material will have a different stress-strain curve.
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Nothing you have to worry about now,
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but realize this is something that you'd learn.
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And there's more mechanical properties,
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but you get the idea.
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Then you'll learn electrical properties,
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like how well materials conduct electricity.
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Thermal properties would, of course,
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be how well heat can flow throughout an object.
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You'll learn the atomic structures and bonding within these materials,
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which is very important because sometimes those structures allow us to determine a material's properties.
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For example, take graphite versus diamond.
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Graphite is relatively soft while diamond is extremely hard,
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yet both are made out of carbon.
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This difference in mechanical properties comes from the way the atoms are arranged in these materials.
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And there's more properties like magnetic properties and optical properties,
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but this is the general idea.
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So now like I said,
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you go over the four main classes of materials,
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and everything you just saw you will apply to all of these.
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But a big one you go over is metal.
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The main metals you go into include aluminum,
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steel, stainless steel, titanium, copper, and so on.
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One important topic dealing with metals you'll learn is heat treating,
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which I'm going to explain a little so you can see its applications.
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You're going to learn how to analyze a graph that has temperature versus time.
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The temperature may go up to something like 800 degrees Celsius and down to let's say 100.
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And let's say this is for something like steel,
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which would be solid at all of these temperatures,
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because again you don't really go into liquids or gases.
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And the time may go from one second to something like a hundred thousand seconds or about 28 hours.
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Then on the graph you'd be given something like this.
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Don't even worry about what these are right now,
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just realize these are the different transformations the material can go through.
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Different materials have different looking graphs,
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just like this red and green curve actually represent two different steels.
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So let's say we heat up steel to about 800 degrees Celsius and start there.
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Then we cool it to 100 degrees Celsius in one second, so very quickly.
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That curve, or line in this case,
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tells us which transformations this material goes through during cooling.
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See how it goes through those regions with an M?
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This goes through different transformations than if we slowly cooled it to the same temperature over the course of about a day.
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So what does this do?
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Well, if it's cooled very quickly like that first line,
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that might yield a very hard but brittle material.
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If you cool the material slower,
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it may yield a slightly softer material,
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but that is much tougher and doesn't break easily.
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It's all the same material,
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but we can achieve different mechanical properties just by cooling it differently.
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Now moving on, you may do projects or reports on basic objects,
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but go into depth on the material beyond what you may know.
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These projects can be for anything,
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but since we are on the topic of metals,
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at one school students did a project on an ice cream scooper.
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Seems simple, but what you may not know is that there is heat conducting fluid within the scooper.
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This is designed to transfer the heat from your hand to the metal of the scooper,
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and this warms the metal so that when you scoop the ice cream,
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it kind of melts the ice cream,
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making it a little easier for you to scoop,
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as well as making it so that the ice cream does not stick to the metal.
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Also, you can't read the words on the box in this image,
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but on it it says new aluminum alloy that helps resist corrosion.
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So hopefully you're seeing how the materials used in nearly everything
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down to a simple ice cream scooper are optimized by the designers and how corrosion is a huge field as well.
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Now I want to skip to composites.
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This is something you may take an entire class on in undergrad.
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Composites are made up of at least two different materials from the other three categories.
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These are crucial because many technologies of today require materials with certain properties that cannot be met with normal metals,
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ceramics, and polymers.
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For example, when it comes to aircrafts,
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we are trying to find materials that are strong,
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stiff, and have low densities and more,
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which is a tough combination of properties to achieve.
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Often strong materials are also dense as an example.
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So engineers are trying to design and find materials that can provide the properties we want to achieve,
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which is where composites can come in.
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So you're gonna learn about these mechanical properties,
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look at stress strain curves of fiber reinforced composites as a random example,
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methods of manufacturing composites, and so on.
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Now I'm really not gonna cover ceramics and polymers in any detail,
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but if you wanna know some basic examples,
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Ceramics might be like a china cup,
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a brick, or a dining glass.
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And polymers or plastics might include a bicycle helmet,
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pool balls, dice, and so on.
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Now these are very basic examples,
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but in school you cover more advanced materials that have engineering applications,
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like silicon carbide that can be used to create very hard ceramics
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which can be used for car breaks all the way to bulletproof vests.
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Also note that there are many materials that we've all heard of,
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but there are way more that you probably haven't heard of.
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These are just a few out of hundreds that were just in an intro textbook on materials engineering.
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No, you don't have to memorize all of these,
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but this is a challenge with materials engineering
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because of the sheer amount of materials out there that all have their different properties.
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Now just briefly, when it comes to labs,
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the equipment you can expect to see would be like microscopes,
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tensile testers, hardness testers, and things like that.
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A lab you might do is cool a material very rapidly,
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then do tensile testing on it.
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You'll use a machine that pulls the object in opposite directions,
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which is what tensile stress is,
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and you'll notice the material is very brittle like we saw earlier.
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You'll use microscopes to look at the microstructures of various materials,
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which is very important.
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Like I said, you'll learn what these mean and how much they can tell you about a material.
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I said that they can reveal material properties,
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but they can even reveal how the object was made like with heat treating and how fast it was cooled.
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For those wondering how much math you see during college,
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there is math and calculus but it's not the majority of the curriculum.
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For example in a kinetics class which you will take,
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one thing you'll learn is diffusion and how atoms move throughout a material.
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So you may have a high concentration of let's say carbon.
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So to represent how the concentration changes over time you would have to use calculus
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because the rate that that concentration is changing at is not constant.
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Or remember that stress-strain curve?
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Well the area under it is the energy absorbed and for those who have taken calculus you know this involves an integral.
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So you see there is calculus and definitely math like algebra and linear algebra that I didn't mention,
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but it's definitely not as much calc and higher level math as an electrical,
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mechanical, or aerospace engineer might see.
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Then as you can see there's also a lot of chemistry which you will learn within your materials engineering classes.
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So if you struggle with math,
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you should expect it in this major and be ready for it,
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but you should also be able to handle it.
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Overall, materials engineering covers a wide range of sectors and there are still many challenges that we face,
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and materials engineers are doing research to overcome these challenges.
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Whether it be to reduce the weight of cars and aircrafts,
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reduce environmental pollutants in the production and fabrication of various materials,
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or finding better materials for fuel cells to improve their efficiency.
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Aerospace, mechanical, and civil engineers are just a few examples of majors
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that also learn about materials and material properties in their curriculum,
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but as you can see,
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materials engineers dive much deeper.
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And lastly, while there is a distinction that can be made between materials science
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and materials engineering and how we categorize and define them,
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at least in terms of undergrad,
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at many schools it will just be called one or the other,
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and you will likely be in the College of Engineering if you go into this major.
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If you liked this video don't forget to comment,
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like, and subscribe and I'll see you all next time.
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在本课中，学习者将通过查看有关材料工程的内容，练习英语口语和听力。通过理解视频中的关键概念和例子，您将增强对材料工程领域的了解，并在此过程中提高您的英语发音和表达能力。此外，您还将学习与材料工程相关的专业术语，以帮助您在相关领域中更有效地沟通。
关键词汇与短语
- 材料工程 (Materials Engineering)
- 结构 (Structure)
- 性能 (Performance)
- 加工 (Processing)
- 失效分析 (Failure Analysis)
- 微观结构 (Microstructure)
- 能量吸收 (Energy Absorption)
- 设计 (Design)
练习技巧
在进行影子跟读训练时，您可以通过 看YouTube学英语 来提升效果。建议您在观看视频时，先专注于听音频的节奏和语调，然后尝试模仿材料工程师的讲话。视频中材料工程师讲解的速度适中，语调清晰，非常适合进行 shadow speech。
为了提高您的跟读技巧，您可以逐段播放视频，并在每段结束后暂停，重复您刚听到的内容。使用 shadowspeaks 的方法可以帮助您更好地掌握发音和语调。重点关注材料工程师在描述不同材料和结构时的语气变化，并在您的练习中尝试模仿这些变化，使您的发音更自然、流利。在练习过程中，不妨记下您觉得特别难以发音的单词，反复练习，直到您能够流畅地说出它们。
什么是跟读法？
跟读法 (Shadowing) 是一种有科学依据的语言学习技巧，最初开发用于专业口译员的培训，并由多语言者Alexander Arguelles博士普及。这个方法简单而强大：您在听英语母语原声的同时立即大声重复——就像是一个延迟1-2秒紧跟说话者的影子。与被动听力或语法练习不同，跟读法强迫您的大脑和口腔肌肉同时处理并模仿真实的讲话模式。研究表明它能显着提高发音准确性，语调，节奏，连读，听力理解和口语流利度——使其成为雅思口语备考和真实英语交流最有效的方法之一。