Detroit’s Big Three love to show off advanced plastics in concept cars, but when the rubber hits the road they are favoring lighter and thinner metals as a fundamental weight reduction strategy. I’ve had the privilege in the last two weeks to interview the top materials engineers at GM, Ford and Chrysler for an upcoming feature story on vehicle light weighting. Development of electric cars is ramping up light weighting efforts so that battery sizes can be minimized. As a result, the autos OEMs are willing to consider higher materials costs than might normally be the case.
One example: polycarbonate was used to make the roof module on the Chevy Volt concept car last year. PC is lighter than steel, and offers improved styling. Yet GM and Ford both have serious technical issues with the material for that application. “Its durability and robustness over time is the question,” comments Mark Verbrugge, the director of GM’s Materials and Process lab. “We’d very much like to use it. We’ve wanted to for years, but we haven’t been able to resolve all of the problems that have come up in our validation programs.” Shawn Morgans, Ford’s body structure technical leader, comments: “It’s (PC for roof modules) something we’ve looked at quite a bit, but it’s another technology that just isn’t ready for prime time. We’re finding some limitations to the material.” Those include weathering and scratch resistance.
The Detroit Three are planning increased use of thinner, high-strength steels, thanks in part to new structural adhesive technology. They are also expanding use of aluminum and magnesium.
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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