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Meanwhile, over at Audi and TVR . . . for the floor of the luggage compartment where it acts as a shear plane to improve crash performance. Over at TVR, Gordon Murray Design (see: adandp. media/articles/mclaren's-pied-piper ) is the engineering might behind the brand's resurrection, where its iStream production process will be used. At the center of every iStream project is an iFrame structure, a lightweight, low-cost architecture built up from laser-cut and profiled large-diameter, thin-wall tubing. These tubes are welded together to create a spaceframe that joins all of the mountings for the seatbelts, seats, suspension, engine and transmission, door hinges, etc., and this structure is then coated with an organic corrosion-resistant material. Normally, low-cost composite panels—iPanels—are bonded to the structure. Made up of woven, unidirec- tional random mat glass or natural fibers sprayed with a low-cost, quick-cure resin, the panels are compressed and mated to a honeycomb core. However, iStream Carbon replaces the glass fibers with carbon fibers while retain- ing the honeycomb core. GMD claims the production system to make the carbon fiber panels is fully mecha- nized, has a cycle time of just 100 seconds, a price point that will allow it to be used in affordable vehicles, can support production of 1,000 to 350,000 units per year, and requires a physical footprint up to 75 percent smaller than that of a typical automotive assembly plant. Audi's R8 combines an aluminum spaceframe with a center tunnel, back wall and B-pillars made of carbon fiber. This lightweight structure weighs 200 kg., making it just over twice as heavy as McLaren's Monocage II. TVR tapped Gordon Murray Design for its new lineup, which will be built using GMD's iStream Carbon process. It consists of a spaceframe made up of large-diameter thin-wall tubes bonded to compressed carbon fiber panels that are built around a honeycomb core. Yamaha and GMD have built concepts around the technology (shown), but TVR will be the first into production. The R8 sports car's Audi Space Frame combines aluminum and carbon fiber, but in a much different mix than at McLaren. The 200-kg (441-lb.) structure uses resin transfer molding (RTM) to produce the carbon fiber cabin rear wall, center tunnel and three-piece B-pillars. In the rear wall crossmember, the fibers are aligned in one direction for maximum transverse strength, with up to 14 layers that form a 5-mm (0.2-inch) thick sheet. The layers used in the B-pillars, on the other hand, are aligned in multiple direc- tions in order to handle both transverse and longitudinal loads. Unlike the rear wall, which has a tensile strength of 3,950 MPa, the tensile strength of the B-pillars is 900 MPa. The R8's front and rear modules are made entirely of aluminum, and the A-pillar nodes, like the other cast nodes in the R8 ASF, have a complex interior geometry that helps to absorb large forces without adversely affecting styling freedom. They join key members of the front structure and occupant cell together, and have a tensile strength of 350 MPa. The bulk of the front and rear modules is formed by a combination of extrusions and cast nodes. Aluminum structural struts stiffen the rear body, while 1.0-kg. (2.2- pounds) oval sections are used to form the upper structure. In addition, the upright section between the rear strut mount and the axle chassis joint varies in wall thickness from 1.5 mm (0.06 inch) to 6.2 mm (0.24 inch) to save 1.3 kg. (2.9 pounds) of weight, while aluminum sheet is used 34 COVER STORY