 2011 Chevrolet Cruze in crash testing. Click image to enlarge |
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Follow Autos on TwitterBy Jil McIntosh; photos courtesy General Motors
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A tour of GM’s crash-test facilities
Milford, Michigan – At General Motors’ crash-testing facility in Michigan, the company rolls some film of an early frontal crash test. A Chevrolet sedan, circa 1936, barrels toward a brick wall; just before the impact, you can clearly see the driver open the door and leap out. It took a certain type of person to do the job in those days.
Today, crash tests are performed in a variety of ways, using sophisticated devices and multi-million-dollar facilities. Not only that, but thanks to advanced computer programs, the idea is to crash as few actual vehicles as possible.
   2011 Chevrolet Cruze in crash testing (top); The range of dummies from large adult to infant (middle); Dummy heads are used to test headliners (bottom). Click image to enlarge |
I visited the facility to watch the company smash up a Chevrolet Cruze, in preparation for the model’s market launch later this year. It all happens in a state-of-the-art facility, upgraded in 2006 to add a $10 million addition specifically for tests involving vehicle rollovers. The research lab tests everything from whole vehicles to some of the smallest components.
Crash-testing is both labour-intensive and expensive. An anthropomorphic test device – what we call a crash test dummy – costs between $100,000 and $150,000, and there are some 200 of them at this location alone. They’re costly because they carry up to 75 measuring and regulator devices inside, and newer ones store their own data for downloading. GM uses a “family” of them, including a new male model that stands six-foot-one (if it could stand: these are built only to sit down) and weighs 230 lbs, versus the “standard” male at 5-foot-10 and 180 lbs. The family also includes an adult female, child and infant, and while it’s still under development, a “pregnant” dummy will eventually be added. Stand-up dummies are also available, used to test for crashes with pedestrians, while disembodied heads are slammed into headliners to assess injuries that could be prevented with better vehicle designs or more use of impact-absorbing materials.
Testing takes place over four buildings, covering a total of 400,000 square feet. Four types are done: component, subsystems, barrier, and suppression tests, which include systems that deactivate airbags when sensors determine that a child is in the seat. Each year, researchers perform some 5,200 component tests, 1,100 subsystem tests, 300 barrier tests, and 250 series tests for suppression systems. Just making sure that everything is accurate is a task in itself: some 2,000 calibrations and repairs are made on the crash test dummies alone, and another 1,100 are done on other equipment. There are also 11,000 videos made and 72,000 still photos snapped each year.
 2011 Chevrolet Cruze in crash testing. Click image to enlarge |
As mentioned, the idea these days is to smash up a minimum of actual vehicles. Thanks to the extensive use of other, more modern methods, crashing is a relatively inefficient method of testing. Instead, automakers use mathematical “models,” or calculations, to determine what forces will act on a vehicle and how they will perform in a crash. GM has been using math models since the 1980s, and while those early ones were crude in comparison, they laid the groundwork for today’s systems, which include sophisticated computer simulations. Actual crash tests are still performed, and probably always will be, but their primary purpose now is to validate the mathematical data. It’s extremely rare that the actual crash test tells the researchers something they didn’t already know.
The math models are important because they can be incorporated fairly early in the vehicle’s design process. In days gone by, companies had to build a car, crash it, determine what had to be changed, and incorporate the changes into the design. With modern methods, crash data can follow the vehicle throughout the process, long before the first car comes down the assembly line.
The company also does subsystem testing using specialized “sleds,” which are partial vehicle bodies mounted on a track. They cost some $6 million each, and GM has three of them. Because the test doesn’t damage the structure, they’re used for as many as three tests a day. Unusually, they don’t move forward toward a barrier; rather, a hydraulic ram pushes the sled backwards, at an acceleration rate that’s 40 times faster than a Corvette, the company said. To the test dummy inside, the forces are exactly the same as in a frontal collision. Twelve onboard imagers in the sled capture high-speed video that’s immediately available to the engineers, and a windshield clamping system allows for quick change of any broken glass, without having to wait for traditional sealant to cure. The sleds are used to test airbags and other systems.
