• Mar 1st 2010 at 10:59AM
  • 8
Fisker Karma Aluminum Space Frame – Click above for high-res image

Fisker Automotive has finally taken the digital wraps off the advanced aluminum space frame around which the Karma plug-in hybrid (PHEV) will be built. In lieu of enjoying a new concept vehicle at the Geneva Motor Show this week, Fisker fans will have to make due with this peek at the bones of the Karma, the part that gives the luxury car its "new levels of rigidity and strength that will give the world's first premium plug-in hybrid electric vehicle world-class ride and handling characteristics."

The frame is made with 5,000- and 6,000-series aluminum alloys. The all-knowing Wiki says the 5,000-series are "suitable for cryogenic applications and low temperature work" but are susceptible to corrosion above 60°C. The 6,000-series are made with magnesium and silicon alloys and "are easy to machine, and can be precipitation hardened, but not to the high strengths that 2000, and 7000 can reach. Now you know.

You can read the original press release announcing the aluminum space frame here.

[Source: Fisker]

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    • 1 Second Ago
      • 5 Years Ago
      I'm a bit perplexed at the use of 5000 series aluminum. I imagine it's 5456 as the rest of the 5's have crap for yield strength. 5456 equally strong as 6061-T6 which is undoubtedly cheaper. The only think I can think of is that 5000 series is required to support some sort of battery cooling system which operates at super low temperatures but it'd have to be below -200 F or so to matter...
        • 5 Years Ago
        The battery pack does run down the backbone/spine of the chassis, so perhaps thats where the heavy cooling goes on - and where the 5000 series stuff is used.
        • 5 Years Ago
        5000 series aluminum have higher ductility and are suitable for stamping and folding operations common with sheet metal. I would imagine that this is used in stampings that have more than 2-3 sheet thicknesses' worth of draw or have small radius bends. In a lot of parts the yield strength is less important than the section modulus for making the part strong and stiff, so the ability to draw depth and section is of higher importance than material strength. A 5000 series would work well here (5052 is commonly used in stamping).

        6000 series aluminum is used in extrusions, which are straight lengths of a 2D cross section that can be machined/bent/welded post-extruding. A 6061/6063 is common and both can be hardened, 6063 can produce a near-mirror finish and may be used for any visible extrusions.

        I wonder if they're going to harden the entire chassis post-welding to strengthen the heat-affected zones. Welding pre-hardened alloy anneals the parent material at the weld and makes weld failure less likely as the parent material would rip away first.
      • 5 Years Ago
      attack of the aluminium frames from space !
      • 5 Years Ago
      Rigidity prevents intrusion into the passenger compartment, but in a side impact,
      there is little crumple zone energy absorption.
      NHTSA allows 80 g's on your spine in a side impact from a 3000 lb vehicle at 30 mph.

      I will soon be granted a patent for a new way to absorb side and rear impacts.
      My invention can reduce the g's to 20 or 30 instead of 80.

      Please help me promote this idea that will save gas and lives.
      • 5 Years Ago
      Wow - at least they are starting to have an actual car.

      Something tells me the Model S isn't engineered to nearly this point yet.
      • 5 Years Ago
      I think it's a good bet that Lotus did some of the engineering on this. Lotus originated the concept of using aluminum extrusions - bonding and riveting them together to build up the superstructure of the car. Extrusions are much cheaper to make than castings or forgings. They also, in the case of Lotus' flexible platform architecture, allow changes in the car's wheelbase or track relative easy since you can just use longer extrusions between the hard points. As far as I know, both Jaguar and Aston Martin have used Lotus' engineering shop to work on their aluminum space frames, and it stands to reason that a small company like Fisker, with limited in-house engineering resources, would also outsource this work.
      • 5 Years Ago
      wow... it actually looks... like a real car!