Fasteners—usually the less glamorous part of a mechanical design—have been grabbing headlines lately. First it was a lack of fasteners that created (or was at least blamed for) the first delay announcement for the Boeing Dreamliner. Now two metallurgists have put out a book that really dredges up the past. In “What Really Sank the Titanic” , coauthors Jennifer Hooper McCarty and Tim Foecke say that substandard rivets were responsible for the rapid descent of the supposedly unsinkable vessel. Metallurgical testing of 48 rivets recovered from the Titanic showed that slag concentrations were at 9 percent, six or seven percent higher than they should have been. Slag is a brittle byproduct of the iron making process. Design engineers put the weaker rivets in areas expected to see less stress, such as the bow. Unfortunately, that is right where the Titanic scraped an iceberg. McCarty and Foecke postulate that fewer compartments would have burst if better rivets had been used. It’s possible, they say, that the Titanic could even have limped into Halifax. They also suggest that the bad rivets may have resulted from a rush to get the boat built at a time when rivets were in tight supply.
HP revealed more of its 3D printing plans in a recent webinar. Senior vice president of inkjet and graphics solution business Stephen Nigro spoke about how the technology works and expanded on HP's vision of open collaboration to commercialize its Multi Jet Fusion 3D printing technology for end-production, and open collaboration on new materials. He also said HP will create software to help users decide when to use Multi Jet Fusion versus conventional subtractive manufacturing.
A lightweight electric urban concept car designed by several European companies weighs only 992 lb without its battery. It would have weighed 26.7 lb more if its windows were made of glass instead of the specially coated LEXAN polycarbonate resin from SABIC Innovative Plastics.
Skylar Tibbits' team in MIT's Self-Assembly Lab is now 4D printing self-assembling shapes made of programmable carbon composites and custom wood grain. The composites are being used in a sport car airfoil, and the wood grain is beautiful.
The NanoSteel Company has produced high-hardness ferrous metal matrix composite (MMC) parts using a new nanosteel powder in a one-step 3D-printing process. Parts are 99.9% dense, crack-free, and with wear resistance comparable to M2 tool steels.
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