Pellini explosion bulge test development

This is called a ratio analysis diagram. It was developed by Pellini in the 1950s or '60s at the Naval Research Laboratory, and it's a complicated slide. I haven't given you this particular one. My paper, "The Future of Metals," has kind of a composite. This one is the fracture toughness versus strength of steels. I'm going to show it for titanium, for aluminum, and then I'm going to show you composites and ceramics and plastics. Your fracture energy for steels of low strength — these are your carbon steels down here; this is yield strength, so your bridge steels and stuff would be even lower, way back at the end of the slide — 10,000 foot-pounds, that's a lot of dynamic tear energy. This is the plastic region. As you get up to higher strengths like 180,000 pounds per square inch, you're approaching the strength of what we use for landing gear on aircraft. The toughness drops off, the energy of fracture drops off as you increase the strength, and it keeps on dropping off until you get up to things like piano wire, and the stuff really doesn't have much toughness.

Pellini at NRL develops fracture methods for Navy nuclear submarine steels; retires to MIT Ocean Engineering; his "ratio analysis diagram" referenced as the diagnostic plot to be discussed.

Then there was another place. A guy named Bill Pellini of the Naval Research Lab in Washington. Later, when Pellini retired from the Naval Research Lab, he came to a place called MIT in the Ocean Engineering Department, now known as Mechanical Engineering. Pellini wrote books, and I'll show you some of the things that he developed for the Navy to figure out how to build nuclear submarines without having them fall apart like the merchant ships did during the war.

Pellini, at NRL, developed the ratio analysis diagram from his work on WWII Liberty ship brittle fracture. Tom built on Pellini's diagram thirty years ago.

Okay, so here's Ashby and fracture toughness versus strength — we've talked about this. But here's a plot I put together thirty years ago, which is called a ratio analysis diagram. Now, I didn't do the ratio analysis diagram. This guy Pellini, who worked at the Naval Research Lab on the Liberty ships that were breaking up due to brittle fracture, was the first person to put together a ratio analysis diagram, which is just fracture toughness versus yield strength on linear scales, not Ashby's logarithmic scales.