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.
NASA's MAVEN spacecraft has entered Mars' atmosphere, carrying instruments to help Earthlings figure out what happened to it. Launched last November, the spacecraft arrived at the red planet right on time after a journey of 442 million miles.
Airbus Defence and Space has 3D printed titanium brackets for communications satellites. The redesigned, one-piece 3D-printed brackets have better thermal resistance than conventionally manufactured parts, can be produced faster, cost 20% less, and save about 1 kg of weight per satellite.
At IMTS last week, Stratasys introduced two new multi-materials PolyJet 3D printers, plus a new UV-resistant material for its FDM production 3D printers. They can be used in making jigs and fixtures, as well as prototypes and small runs of production parts.
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