Lightweighting gives composites new life

Progress in fiber-reinforced resin composite technology opens the prospect of replacing metal chassis and body structures.

Back in the 1990s, when aerospace manufacturers started to build airframe components of business jets and commercial airliners from polymer composite materials, many industry observers felt that it would be only a few years before large-volume automakers would begin to follow suit. After all, the lightweight but strong and stiff composites of fiber-reinforced resin had already made the transition from military aircraft structures to civilian ones, and racecars and exotic sports car prototypes featuring mass-efficient carbon-fiber bodies had started to appear. Yes, composites were still too expensive, but many experts believed that continued technical advancement would in due time yield low-cost, mass-produced auto chassis and bodies that could save fuel while enabling new designs that were never previously possible.

More than a decade later, however, car structures are still made primarily of steel and other metals, and are likely to stay so for the foreseeable future. Plastics-reinforced and not-have found much greater application in interiors and some non-primary structural applications such as body panels and pickup truck boxes made of reinforced sheet molding compound (SMC), but the OEMs, having sunk large quantities of capital in metal-part fabrication and assembly plants as well as paint operations, have retained what critics call a “steel mentality.” In fact, between 2001 and 2007 utilization of thermoset composites-resins that harden permanently at high temperatures-has declined significantly in the automotive sector, according to data collected by the Automotive Composites Alliance, an industry consortium.