There seems to be a rush to judgment to find the flaws that caused the I-35W bridge to collapse in Minneapolis. The new theory—faulty steel gusset plates—strikes me as grasping at straws. Why after 40 years would faulty plates suddenly result in a catastrophic failure? Why has this never been raised before as a potential flaw in this type of bridge? As MIT metallurgist Ken Russell pointed out here recently, steel is made in huge batches, and its chemistry is carefully tested. Suddenly we discovered that this ancient batch was a bad one? Or that the designer used a wrong gauge or grade of steel?
It probably will take months for a meaningful analysis of the bridge failure to emerge. Undoubtedly, the investigators will find a frightening list of contributors to the collapse, starting with the corroded steel roller bearings already reported as deficient in 1990.
Artificially created metamaterials are already appearing in niche applications like electronics, communications, and defense, says a new report from Lux Research. How quickly they become mainstream depends on cost-effective manufacturing methods, which will include additive manufacturing.
SpaceX has 3D printed and successfully hot-fired a SuperDraco engine chamber made of Inconel, a high-performance superalloy, using direct metal laser sintering (DMLS). The company's first 3D-printed rocket engine part, a main oxidizer valve body for the Falcon 9 rocket, launched in January and is now qualified on all Falcon 9 flights.
Lawrence Livermore National Laboratory and MIT have 3D-printed a new class of metamaterials that are both exceptionally light and have exceptional strength and stiffness. The new metamaterials maintain a nearly constant stiffness per unit of mass density, over three orders of magnitude.
Smart composites that let the material's structural health be monitored automatically and continuously are getting closer to reality. R&D partners in an EU-sponsored project have demonstrated what they say is the first complete, miniaturized, fiber-optic sensor system entirely embedded inside a fiber-reinforced composite.
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