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During GM's 10,000th crash test, a Chevrolet Cavalier carrying a dummy passenger crashes into wall at 35 mph. Safety features, including air bags, seat belts and a collapsible steering column, met federal regulations. The first challenger was the more sophisticated EuroSID, from government laboratories in Europe. But U.S. automakers say EuroSID's chest is too rigid. And so GM researchers, working with the industry-wide Society of Automotive Engineers, created the even more refined BioSID, or "Biofidelic Side Impact Dummy." 'Biofidelic" means "close mimicry of the human body." And biofidelity has won BioSID many auto industry fans, who hope the new dummy will replace SID as the federal standard. As Steve Rouhana puts it: "With BioSID, you can compute the viscous criterion." The viscous criterion is a formula developed by GM researchers. It can exploit BioSID's keener sensors and biofidelic body to better portray a side collision. The formula accounts for how much, and how fast, a body compresses on impact. The more rapidly tissues compress, the more they stiffen and become vulnerable to damage. According to industry experts, SID's relatively crude instruments mainly reveal what a crash does to his bones. BioSID, on the other hand, can give a better reading on the overall risk of internal organ injury. In dummydom, such sensitivity is what test pilots call the right stuff. But the first modern, instrumented dummies, which came along just after World War 11 as test pilot stand-ins, didn't have much stuff at all. In the beginning there was Parachute Man. That was in the late 1940s, when jet fighters first appeared. Crashtest dummies were needed to test ejection seats, but the early dummy designers had no knowledge of how to build a human simulacrum. And so they started with rulers. "One guy went around measuring people-how long is a femur?" says H. L. (Bud) Mertz, a GM expert on biomechanics and safety restraint development. Mertz is reminiscing with his longtime Milford Proving Grounds associate Tom Terry. The early ejection-seat dummies, they point Out, were basically steel barrels with limbs and heads. It was the auto industry, starting in the 1950s, that started the dummies evolving. With enactment of the National Highway Traffic Safety Act of 1966, dummy evolution took off. Now the engineers were working on seat belts and air bags, which exerted complicated forces on a body. GM took the lead in 1971, creating the Hybrid I dummy, which GM made available to the entire industry, a practice it has continued. By 1976 researchers had produced the sophisticated Hybrid 111, which will be the standard federal dummy after September 1, 1997, although it is already widely used. It is the most humanlike dummy so far, with major exceptions: Hybrid III's designers omitted ears, eyes, nose and mouth. As physicist Steve Rouhana puts it: "At even 30 miles per hour, if you hit the windshield, your nose disappears anyway." Except for their blank faces, Hybrid Ills come from the factory fully loaded. At GM's ATD Lab (''ATD'' stands for "Anthropomorphic Test Device," officialese for "dummy") senior supervisor Joseph Balser shows off the After visiting GM labs 10 research this story, writer Richard Wolkomir reports that he is "very, very careful" to adjust shoulder and seat belts Property. low AV Hybrid III 50th Percentile Male. "Its head decelerates when it hits the steering wheel, and it has three accelerometers inside its head to measure that deceleration in three directions," says Balser, adding that the readings show what the crash would do to a human's head. Balser gazes paternally at Hybrid 111. If you press the dummy's forehead, it feels oddly human, like skin over a skull. However, Hybrid III is only a highly sensitive machine. Sensors in its neck (it moves just like ours), in its steel, vinyl-graphite-layered ribs (they deflect just like ours) and on down in its lower legs, measure everything from impact on the pelvis to knee shear and loading on the tibia, sending the data to computers. Safety engineers are studying "submarining"--wear your lap belt too high and you may slide under it at impact, possibly injuring your abdomen. To work out anti-submarining belt designs, engineers gave Hybrid III a styrofoam abdominal insert: how much it crushes reveals the potential injuries to a human. Hybrid III is still evolving. For one thing, seat belts and air bags have reduced fatalities and upper-body injuries, with serious head in injuries juries down substantially. So researchers are looking at other dangers, like leg injuries. "We're designing knee restraints; this may require more leg instrumentation in the dummies," says Bud Mertz. Such refinements must be meticulous. Tom Terry displays a Hybrid III steel pelvis. "It's important to get the geometry of the load-bearing bones right; to design this pelvis we went to the University of Michigan and measured pelvic size on a bunch of skeletons," he says. Mertz and Terry recall dummy design's Paleozoic Era, when they both were graduate students at Wayne State University, a center for such studies. The stumbling block was that nobody really knew how a human body would respond to ejection-seat or car-crash forces. And so, many researchers got on sleds and tested themselves. Scientists at our service "my major professor volunteered for everything, so we'd instrument him and put him on an impact sled," says Tom Terry. "You'd start at very low forces and work up in discrete increments, to keep in the safe zone." In the unsafe zone, the scientists manned the sleds with cadavers, using bodies willed to research. These days bioengineers also visit trauma clinics to learn from actual accident victims, while some cadaver research continues at universities. So do volunteer studies. When GM researcher Annette Irwin helped develop a child dummy that would have accurate shoulder movements, she measured her own kids. Still, dummies remain mere contraptions. At First Technology Safety Systems, in Plymouth, Michigan, where the 90 workers manufacture most of the world's crash-test dummies-about 300 a year-you can watch dummies take shape from blocks of steel, aluminum and plastic goo. "Now, here they're making a clavicle," says Gordon Morgan, director of quality assurance. "We x-ray the part to check the porosity of the aluminum bones to make sure they don't break prematurely in a crash." Other workers are brewing skin from liquid polyvinyl chloride plastic. After the plastic bakes into skin of correct thickness, grinding disks and hot irons make it smooth. "Now we're developing a facial skin that shows lacerations and abrasions," says Morgan. At First Technology it is perpetual Halloween. Benches are strewn with feet and hands. Here are the bones of the neck being molded together, the metal vertebrae separated by rubber disks. And over here, like something from a discarded Stephen King first draft, is a dummy's disembodied behind, inscribed with quality control graffiti: "Poor cosmetics," "Bad surface," "No bumps." Beside it is a head with a message scribbled across the chin: "Bad!" And here is a finished Hybrid III supine in its coffin-like shipping box, flanked by its unassembled legs. It might be a Neolithic burial. But this dummy is actually just starting its macho career. |