Titanic

The Titanic had brittle steel, but the problem was the iceberg cut through six compartments and all six of them flooded, and it became heavy on one end. It wasn't until the early 1930s that we started building critical structures of all-welded construction. The first one was the Big Inch pipeline from Louisiana up to New Jersey. It's a 30-inch diameter gas pipeline, and it was all-welded construction — first really critical thing that had been built. As far as I know it was successful; it probably was taken out of service for corrosion, or it just wasn't big enough — we have much bigger pipelines and higher strength pipelines now that can take more gas pressure. But it was World War II when we started to go into all-welded steel construction that allowed the Liberty ships, if you get a crack start it could run all the way around the ship and split the ship in two, because there was nothing to stop the crack.

Tied to the Kielland and Petrobras cases as a third "hatches and compartmentalization" failure — gash spanned six compartments where design tolerated four.

Which is actually also the reason the Titanic went down. It was unsinkable and had all these compartments, except the gash went for six compartments along the side and it could tolerate four. Who would ever expect a gash the length of six compartments? Sort of similar to this guy in Italy who went close to the rocks. The failures just keep coming back.

Brief reference — Tom mentions his History Channel appearance demonstrating paper-tearing as an analogy for flaw-controlled failure. Not developed; treated as a known external reference. ## Figures referenced These are framing-numeric anchors, not cases:

And why imperfections control the strength of materials. Anyone ever heard that bucky balls and nano graphene and stuff are super strong? Absolute garbage. A physicist's pipe dream. I can take a sheet of paper — you'll see me doing this on the History Channel when I talk about the Titanic — and pull on that piece of paper with pounds of force. But if I put a flaw in, that takes ounces. The inherent strength of a material may be millions of PSI, and you can do the calculation. I do it in the joining lectures. A carbon nanotube should have two or three million PSI strength. That's only true if you don't have a vacancy. If you have an atomic vacancy, then it's just like having a defect. If you really made a real carbon nanotube, it would fail at 1/10 the theoretical strength.

Referenced briefly in connection with Tom's History Channel appearance and the paper-tearing demonstration of flaw-induced strength loss in brittle materials. Not developed here. ## Figures referenced

To give you an example — you'll see me doing this on the History Channel, I talked about the Titanic — [Tom demonstrates with a piece of paper.] you can pull on the edge of this material, paper, with pounds of force. If I put a flaw in the material, which is what Griffith was looking at — flaws in glass — I can lose eighty to ninety percent of my strength because of a flaw in a brittle material. Whereas if I have a ductile material, like rubber — [Tom demonstrates with a rubber band.] — that is toughness. I can pull on that piece of rubber and I don't have a sharp notch, I blunt the notch, and so I get lots of deformation without fracture. There's a tremendous difference in ductility of fracture versus brittle fracture, and we're going to talk about that stuff on Monday. Have a good weekend.

Identifying mention only — ALVIN "went down and found the *Titanic*."

So they had a huge welding institute and they developed technologies like — if you've ever read The Hunt for Red October or seen the movie, they had titanium submarines. My first research project, in 1977, was from the US Navy to weld titanium for submarines. [Tom holds up a 1977-era titanium weld sample.] This probably belongs in the Smithsonian. We were welding 1-inch-thick titanium for submarines. The United States wanted to build titanium submarines. We never built one, other than the deep-sea research vessel Alvin that went down and found the Titanic. The Navy built that as part of a prototype program to learn to weld titanium for bigger ships, because titanium submarines have the same strength-to-weight ratio advantage that aircraft and fast-moving vehicles need. You want high strength-to-weight so you can dive deeper and, hopefully, if you lose power, pop to the surface rather than sink to the bottom — because if you sink to the bottom, everything gets crushed, including the people inside.

Listed as an example of a technology-focused paper topic past students have chosen. Not developed.

You could take a technology — one student did Japanese sword-smithing. They used to have a little display in the hallway of these students who had made a Japanese sword on their own. Some students have done the HMS Titanic. Some students from nuclear engineering have done nuclear power plants. A couple of students one year both did pole vaulting. They were both pole vaulters at MIT. Turns out a pole for a pole vaulter — you ever seen them, they bend more than 180 degrees and they don't break. It's because it's a composite material that's layered and has variable stiffness. It's actually very interesting technology.