§1. Sign-up and course staffing [00:03]
This is organization day. Let me pass some of these around. I still do the old-fashioned thing because I've never trusted the registrar for the last 37 years. These are sign-up sheets just so I know your email and department and your name. It has nothing to do with signing up for the course — you have to do that through the registrar. But it helps me know early on, because the registrar doesn't give me a list until much later in the term.
My name's Tom Eagar, and some of you have taken a version of this before. I teach three courses during the year: 3.370, 3.371, and 3.372. They're all something about Structural Materials. This semester I'll be lecturing, Dr. Belmar will be lecturing, and Mike Bonforth will be lecturing. Mike is a certified welding engineer and a certified welding inspector, and my module — which Mike will be doing with me jointly — is welding metallurgy. Simone is going to be talking about uses of Structural Materials. It has to do with quality control and capacity of materials.
Today is sort of an introduction. The course is actually taught in a series of modules, and you have to take about 36 hours of lectures.
§2. The module catalog [02:18]
This is a sheet from my website. If you go to the MIT website and put in my name, you'll find something called Eagar Group, and on that you will see this list of 12-unit modules I have taught in previous years. The website now lists the year. Last summer I taught Fusion Welding. During the summer I teach the Course 2-N students — Navy officers, around thirty years old plus or minus a couple of years, who come back to get a couple of master's degrees at MIT before they go off and design ships for the Navy. They have to have certain things according to the Naval Sea Systems Command for their curriculum at MIT, one of which is welding metallurgy, which was covered years ago by Professor Masubuchi. When he retired, I started covering it.
You might find one or two lectures on welding metallurgy in the 12 units of Fusion Welding, but probably not. This semester Mike and I decided we would try to put together a real fusion welding course. It is the metallurgy of welding, so in a sense you can think of it as a crash course in physical metallurgy of different materials. In welding metallurgy this semester, Mike and I will do a number of lectures on steels, then high alloys — stainless steels and nickel-base alloys — then aluminum alloys, titanium alloys. We can do any alloy you want.
We can do iridium if you want. There is actually an application for welding of iridium about once every 25 years. They weld up little iridium spheres around plutonium. When NASA has a space shot that goes into deep space — passing by Uranus or Neptune or Pluto — there's not enough sunlight energy to power the spacecraft for 40 years. So they put a piece of plutonium in there which generates heat, and they have thermoelectric generators, which are very reliable electrical sources. The Voyager spacecraft that's been going for 30 or 40 years is powered by a piece of plutonium surrounded in iridium. Just in case it blows up when it's going up into orbit, rather than spreading plutonium all over the Atlantic Ocean, they end up with one little iridium sphere they can go look for. Don't tell anybody they're putting plutonium in spacecraft that could crash during the boost stage of the rocket, because the environmentalists would get all upset. NASA doesn't advertise that anymore.
There are applications of welding all kinds of Structural Materials. Fusion welding is something where I basically start out with flames, go through arcs, lasers, and electron beams, and talk about the process. You go from a thousand watts per square centimeter as a heat source up to a million watts per square centimeter. What are the different physical interactions that occur? If someone wanted to take Fusion Welding, that's a 12-unit module. You basically have to get three full modules of 12 units. We will be teaching one and a half modules this semester live, and you're going to have to pick up some other modules on your own.
Those of you who've taken the course before know that Manufacturing and Use of Structural Materials was Dr. Belmar's. That focuses on Structural Materials. My Material Selection is sort of a 100,000-foot view of how you select materials and get into economics and externalities. Dr. Belmar's is basically looking at what type of properties you can get out of aluminum alloys or titanium alloys or steels, and how you can use those in design.
Solid State Welding is the first part of my total welding course. It's 12 units on adhesive bonding, brazing, soldering, and diffusion bonding — anything that's not melting metal to make a fusion weld. All those other welding processes — explosive welding, cold welding — go in there.
§3. Codes and standards [07:32]
Codes and Standards is on there twice because it was a new course. If I'm going out to manufacture something, I can't just go do anything I want — there are lots of rules and regulations out there in the world. The government tells me that some things are by force of law: if I don't do it the way the city of New York says, or the federal government in the Department of Transportation says, I can't sell the product. By the same token, some standards contain the historical knowledge of how to do things right and not have a big screw-up.
Historically, some of our codes and standards have been written to correct for major mistakes. For example, the Northridge earthquake in Southern California 20 years ago — a lot of buildings and bridges came tumbling down, or were damaged to the tune of like $15 billion worth of damage. A lot of the building codes were modified to allow for earthquake vibrations. The Japanese have been doing that for 20 years because they have a lot more earthquakes than we do, but back in the 50s and 60s we didn't design bridges and buildings in Southern California to accommodate those things. You still read in the news about an earthquake in Chile or Iran, and 10,000 people died because the concrete buildings just collapsed on people. We actually can design things, because of different codes and standards.
I talk about the politics of how codes and standards fit into both regulation of the government and engineering — how it can be the corporate knowledge that teaches us from the mistakes of the past, but also can stifle innovation.
§4. The remaining modules [09:38]
Deformation Processing — if you're interested in forging, sheet metal forming, wire drawing, any way to form ductile materials — that course goes through the physics of forming and processing using stamping presses, forging machines, wire drawers, and so on. Structural Life Assessment, Dr. Belmar taught a module on that. It's basically fatigue and fracture, but from the point of view of a designer, of what you have to consider, as opposed to getting deep into the physics of the fracture. There is another course on the physics of the fracture in the department Dr. Belmar teaches in.
There's a casting course here, and I call it Intro to Materials Processing, because this is where I take my shot at nanomaterials. It's only about a lecture and a half about how nanomaterials will never be used for Structural Materials. They may be interesting for functional materials, but structural nanomaterials are going to be too expensive for most Structural Materials, unless you're talking about spacecraft. If you're building a bridge across the Charles River, you're not going to make it out of nanomaterials in spite of what all the researchers around tell you. I haven't had that discussion with the department head since last Thursday — we had a faculty meeting offsite, and I made some comment about nanomaterials and he started telling me how wonderful they were. We have a difference of opinion.
Solid State Welding is the old version. I try to renew these every three years, so there's the old version of that. Material Selection, Fracture, NDT, and Welding Metallurgy — you're getting the welding metallurgy. This is where I had three or four lectures on NDE. I may teach a course on that this summer to the Navy guys. I used to teach some fracture mechanics, but that's sort of been supplanted. Material Selection has been supplanted by the one I did last fall, Introduction to Material Selection — that's the 100,000-foot view. Fusion Welding is the old version of this one up here. I've been videotaping these for over 20 years now, and how an old one got in here I don't know, but it's on there. Then there are some other archetype ones that are just a selection of some of these from even older times.
Christine, which modules did you take last time? You can tell people what that is. You also took my live course, and you probably took Dr. Belmar's course. So you took 24 units live and 12 units by video. Jonathan, what did you take last time? Anyway, you're welcome to take whatever you want, but you can't take something you took last time. You have to take approximately 36 lectures, because that's what you get in the 12-unit course at MIT.
§5. Schedule and assignment options [13:42]
Some of you know that I schedule this quite a bit differently than the regular MIT course. We meet every day of the week that's a scheduled class day, 9 to 10 in this room. If everything goes perfectly, we would be finished by the end of February with the lectures. We actually probably won't finish until early March, because I've got to be out of town on Friday. Dr. Belmar's lecturing on Friday. I'm lecturing today and tomorrow, and Dr. Belmar — I'm lecturing on the 10th. I'll give you the schedule in a little more detail tomorrow. Mike Bonforth is doing the 12th and 13th of next week, and I'm doing the 14th — come here for Valentine's Day.
We do the lectures, and it's front-loaded. You get things to read. You don't have to read them, but you can. If you read the course evaluations from prior years, one student says you can get a lot or a little out of the course depending on how much you want to do outside of class.
Student: What are you required to do outside of class? What's the assignment?
If you really want to do a term paper, it would be a 10-page term paper. If you don't want to do a term paper — the preferred method, most students do a presentation in class. This will probably come right after spring break, beginning of April. We'll do two or three of your presentations a day. Those of you who did it last term, you have to come up with another topic — you can't give the same presentation you gave last term. Or if you really couldn't do either one, you can talk to me. I do have an old homework set on the old welding stuff of 10 problems, and you could do the 10 problems. You only have to do one of these.
Those of you that have been in this class before know that I give a little lecture at the beginning of how I have a bad attitude about the way we do education — that students both in high schools and in colleges are just prepped to take quizzes. I don't think that's a very good learning environment. I started realizing this 20-some years ago. One of my kids left their high school math book on the kitchen table, and I was sitting there eating breakfast, flipping through it. It had two pages on every mathematical topic you can think of: matrices, exponentials, logarithms, differentials, integration. So everything in math could be taught in two pages by definition, in this high school book. And I look at it and say, well, this is just coaching you to answer some of the questions on the SAT exam.
That's to a certain extent what happens at MIT. What do we get at MIT? We get some of the brightest students in the world who have proven that they know how to take quizzes. You couldn't have gotten here if you didn't know how to take quizzes. So many MIT students like to compete with their peers by showing that they can get good grades on a quiz. You take my course and you're out of luck. There's no quizzes, there's no final exams. You can't show how much smarter you are than your classmates. But hopefully you can just enjoy learning.
You don't have to take a copy of this if you were in the class last term, but I hand out this article I wrote for the faculty newsletter on education at MIT. It's the same one I handed out in all my classes, to tell you about my good or bad attitude about education. I was very pleased for years that no one had to take my course — it wasn't required for anyone. If you want to take the course, we're here to try to learn about different things.
That's the assignment. I'm supposed to tell you, therefore there is no possibility of cheating in this class, so I don't have to tell you about cheating. You shouldn't cheat. I don't know how you would cheat in a class like this. Are you going to download some presentation off the internet and try to give it? I don't care — you're the one who's paying big tuition to try to get around the system.
That's all I had: sign up, schedule, assignments, and the different modules. Any questions on overviews?
Student: [inaudible question about deadline for the videos]
You have to have them done before I have to turn the grades in, in May. You can start watching them now, or you can start watching them on May 10th and cram them in at the end.
That's another one of my philosophies. Students come to me and say, what do I have to do, or, give me a deadline. I've had my own doctoral students have to write up their thesis, and one of them said, well, give me a deadline. I said no. He says, well, I work better under deadlines. I said fine, set one for yourself. My job is to train students on how to be professionals, and a professional does not need someone else to give them a deadline. So you're a professional here. You get a schedule and you do these things.
One student on an evaluation said they watched them while they were fixing dinner at home. So I'm in the background. I put on a Celtics game while I'm working at home — fine, it's in the background. If there's a play, there's always going to be a replay and I can look up. So if you're fixing dinner and all of a sudden you hear a story you want to hear, you can let the carrots burn while you listen to my story. I don't care when you do it.
If I get involved in MITx or edX, I'm probably going to have some way to ensure that the students actually watch the videos. Those of you who took the thing last term will know I don't even check up on you. If you didn't want to listen to the live lectures, you could take 36 lectures all by video, and that's one of the beauties of it, to me. If we videotape the lectures, anybody in the world can take this course, but only you can get credit, because you paid the tuition.
I've been putting my course online for 15 years now, before MITx and edX. I know that there are professors at other universities, when they have to go out of town, who pull off one of my lectures and show it to the students while they're gone. Because it's just Tom Eagar and stories. It's kind of like having a guest lecturer, when someone tells a story.
§6. The teaching philosophy: analogies, not commandments [21:43]
From my point of view, you're here to learn, and one of the things I'm trying to do is help you draw analogies. There are some people who just spend all their time lecturing — telling you, it's kind of like Moses coming down from the mountain and giving you the Ten Commandments. These are the Ten Commandments of engineering and you should learn this.
I believe in a different philosophy. I would much rather convince you that you already know the answer to many things — you just never had someone tell you how to put it together. When I'm talking Fusion Welding and I have to talk about arcs, one of my favorite lectures is what I call the fluorescent light lecture, where I tell you the difference between a high-pressure arc — which is a welding arc at one atmosphere pressure, and that's what the physicists call it; one atmosphere is high pressure to a physicist — or a fluorescent light, which is at a lower pressure. If you break a fluorescent light, it implodes and you hear it go pop. It implodes because it's like a fifth of an atmosphere, and it's a glow discharge. We have fluorescent lights in this room.
Fluorescent lights are cooler than an incandescent light, but LEDs are even cooler. What's the physics of giving off light? And what does that have to do with welding? Zippo. Unless you're using light to weld — some people do, they use very intense light sources as a heat source to weld plastics. Some people have even welded some metals using very intense light sources.
Nonetheless, you need to understand the basic physics of how plasmas cause heating or non-heating. It turns out a fluorescent light is a two-temperature plasma: the electrons have a temperature of 100,000 degrees and the ions have a temperature of 100°C. That's why you can put your hand on a fluorescent light — what you feel is the ion temperature. You can't feel the electron temperature, but you can see it. It's the electrons that give you light. Same thing in an LED: it's the changing of the direction of the electrons that causes them to radiate and give off light. In that case you don't even have to heat up ions, so LEDs are more energy efficient than fluorescent lights.
So what I get to do by teaching you welding is teach you about all kinds of little physical things that I've learned over the years. You actually learned most of this in freshman physics, but no one ever told you how it fit together — because whoever was teaching you, a physicist, they haven't a clue how it fits together. I was a student here, and I look back and think, how come they never told me about these things. I learned in thermodynamics how to calculate a heat engine up one side and down the other, but I couldn't tell you how an air conditioner worked. Did you know an air conditioner is a heat engine? No one ever told me that. I had to learn that in the gutter of going out in the real world. But an air conditioner is a heat engine.
One of the things I'm trying to help you do is learn that all these things you learned when you got the MIT science education are actually useful pieces of knowledge, if someone actually shows you how to use them. If you learn how to use them in a few examples, I bet you can figure out how to use them in other examples and be creative in your own way. So it's a different philosophy than Moses coming down from the mountain saying, here are the Ten Commandments of welding. It's more, well, did you know that fluorescent lights are just a different type of arc?
Or my adhesive bonding lecture in Solid State Welding — someone asked me to give some examples — I call it the Scotch tape lecture. Why does Scotch tape, if you put it on the wall, later fall off if it's holding something up, whereas duct tape holds things much better and much longer? But if you put Scotch tape on and it falls off the wall, why do you go over and push it on even harder, hoping it'll stick longer? It just turns out to be a viscous flow equation. If you learn about the viscous flow equation, you'll understand why duct tape works better than Scotch tape, and why dirty Scotch tape doesn't work as well and doesn't last as long. You also learn about all kinds of adhesives. Jordan's learning about adhesives — she's doing a bachelor's thesis on adhesives. She's actually watched that lecture.
These equations have been around for years. It's just that no one ever teaches them to you in context. So I consider these context subjects. Any other questions? Simone, you want to give an example of some of yours?