1 00:00:15,960 --> 00:00:17,733 Ok. Why does this matter? 2 00:00:17,733 --> 00:00:19,250 Well, this is one reason. 3 00:00:19,250 --> 00:00:23,816 If you don't plan your cold work carefully, 4 00:00:23,816 --> 00:00:26,083 you might make the material too brittle. 5 00:00:26,083 --> 00:00:27,983 You wanted it to be so hard because this 6 00:00:27,983 --> 00:00:31,783 was such an important ship and it was going to be a big deal 7 00:00:31,783 --> 00:00:33,233 and the launch was really exciting. 8 00:00:33,233 --> 00:00:36,900 And then it cracks in half, the entire ship. 9 00:00:36,900 --> 00:00:37,533 Why? 10 00:00:37,533 --> 00:00:41,300 Because you didn't look up what dislocations mean. 11 00:00:41,300 --> 00:00:46,800 You didn't take 3.091, that's why. 12 00:00:46,800 --> 00:00:47,883 That's a pretty big crack. 13 00:00:50,933 --> 00:00:52,316 The main why this matters-- 14 00:00:52,316 --> 00:00:54,133 oh, I couldn't help it. 15 00:00:54,133 --> 00:00:57,950 I am a big fan of wind. 16 00:00:57,950 --> 00:01:00,150 Wind energy is growing and growing 17 00:01:00,150 --> 00:01:04,450 and it's such a great national resource. 18 00:01:04,450 --> 00:01:07,016 Here's the global capacity. 19 00:01:07,016 --> 00:01:12,333 This is install capacity for wind turbines. 20 00:01:12,333 --> 00:01:17,183 But see, this is a mechanical materials problem 21 00:01:17,183 --> 00:01:24,383 that you are now equipped to think about more deeply. 22 00:01:24,383 --> 00:01:29,050 Because, you see, you can do a lot of different experiments 23 00:01:29,050 --> 00:01:29,800 on those turbines. 24 00:01:29,800 --> 00:01:32,783 So the blades here are critical. 25 00:01:32,783 --> 00:01:35,850 You can imagine that you want them to be light, 26 00:01:35,850 --> 00:01:38,583 but if they're too light, they may not be strong enough. 27 00:01:38,583 --> 00:01:40,200 And then how do they need to be strong? 28 00:01:40,200 --> 00:01:45,083 Because you've got huge amounts of wind coming at them. 29 00:01:45,083 --> 00:01:48,666 And it turns out, you need to hit just the right balance 30 00:01:48,666 --> 00:01:54,583 of elastic deformation before it goes into some plastic regime. 31 00:01:54,583 --> 00:01:57,133 You need to hit just the right balance of ductility. 32 00:01:57,133 --> 00:01:58,700 So here's, for example-- 33 00:01:58,700 --> 00:01:59,850 these are some simulations. 34 00:01:59,850 --> 00:02:03,300 Here are some experiments on a new material for a wind turbine 35 00:02:03,300 --> 00:02:04,233 blade. 36 00:02:04,233 --> 00:02:08,583 And then you put it out there and look at what happens-- ice. 37 00:02:08,583 --> 00:02:12,183 By the way, this ice comes off at hundreds of miles an hour 38 00:02:12,183 --> 00:02:13,200 in chunks. 39 00:02:13,200 --> 00:02:16,200 These farmers are not happy about that. 40 00:02:16,200 --> 00:02:17,650 Seriously. 41 00:02:17,650 --> 00:02:18,483 And those are bugs. 42 00:02:21,100 --> 00:02:24,366 Actually, bugs in wind turbine blades is a serious problem. 43 00:02:24,366 --> 00:02:26,733 How do you clean bugs off of it? 44 00:02:26,733 --> 00:02:29,250 Because it dramatically changes the aerodynamics 45 00:02:29,250 --> 00:02:30,300 and the efficiency. 46 00:02:30,300 --> 00:02:33,550 It also can damage the blade itself. 47 00:02:33,550 --> 00:02:35,383 So there's all sorts of work going on. 48 00:02:35,383 --> 00:02:38,600 How do you make bug-proof wind turbine blades? 49 00:02:38,600 --> 00:02:39,100 OK. 50 00:02:39,100 --> 00:02:40,716 Well, now just spray it with something. 51 00:02:40,716 --> 00:02:43,566 Ah, but then does it have the right plastic deform-- 52 00:02:43,566 --> 00:02:45,200 does it have the right yield point 53 00:02:45,200 --> 00:02:46,416 or is it just going to crack? 54 00:02:49,133 --> 00:02:53,200 And by the way, it's got to have 5 times 10 to the 9 cycles 55 00:02:53,200 --> 00:02:54,516 before it can fail. 56 00:02:54,516 --> 00:02:56,000 That's the metric. 57 00:02:56,000 --> 00:02:58,200 So that's a pretty big ask of a material. 58 00:02:58,200 --> 00:03:01,233 It all comes down to understanding this curve. 59 00:03:01,233 --> 00:03:05,500 And in the broader sense of materials, this to me 60 00:03:05,500 --> 00:03:08,400 is a very exciting ask. 61 00:03:08,400 --> 00:03:09,850 Why? 62 00:03:09,850 --> 00:03:15,283 Because if you look at a plot of the density of materials-- 63 00:03:15,283 --> 00:03:16,700 heavy, light. 64 00:03:16,700 --> 00:03:17,533 Good. 65 00:03:17,533 --> 00:03:18,850 Kilograms per meter cubed. 66 00:03:18,850 --> 00:03:20,783 And the Young's modulus-- 67 00:03:20,783 --> 00:03:25,483 now, this is a measure of the strength of the material. 68 00:03:25,483 --> 00:03:28,750 It's a measure of how much strain 69 00:03:28,750 --> 00:03:31,850 you could put on the material before it breaks or goes 70 00:03:31,850 --> 00:03:32,683 through deformation. 71 00:03:32,683 --> 00:03:34,033 But look at this. 72 00:03:34,033 --> 00:03:36,466 Different materials are here-- 73 00:03:36,466 --> 00:03:38,316 rubbers, foams. 74 00:03:38,316 --> 00:03:42,250 OK, foams have relatively low Young's modulus, 75 00:03:42,250 --> 00:03:43,300 but they're really light. 76 00:03:43,300 --> 00:03:44,783 That could be good. 77 00:03:44,783 --> 00:03:48,733 Up here you've got metals and alloys, ceramics, 78 00:03:48,733 --> 00:03:50,650 you've got polymers in here. 79 00:03:50,650 --> 00:03:54,550 But notice, I've got so many different applications 80 00:03:54,550 --> 00:03:57,133 and needs in the applications and I've 81 00:03:57,133 --> 00:04:01,333 got this plot where I've got nothing here and nothing here, 82 00:04:01,333 --> 00:04:05,883 even though, if I could fill this out and dial up 83 00:04:05,883 --> 00:04:11,650 any stress/strain curve for any density or Young's modulus, 84 00:04:11,650 --> 00:04:13,233 you can make a big difference in a lot 85 00:04:13,233 --> 00:04:14,300 of different applications. 86 00:04:14,300 --> 00:04:16,882 So I think this is a great challenge.