As one of the last steps, the precisely positioned crash test dummies are given a chalk makeup job. The use of different colors allow exact analysis of how a chin, nose, forehead or cheek contact the deploying airbag. When all is ready, the ServoSled (short for servo-hydraulic sled) simulates a 35-mph collision impact involving an acceleration of over 50 Gs, knocking the vehicle sled weighing up to 3,000 pounds backward down a 100-foot-long tunnel. From four to 12 technicians and engineers cluster in the control room, which then is carefully locked and the lab entrances sealed for safety. A technician says “Here we go”; a voice counts down – “five, four, three, two, one” – and with a blast like a cannon being fired, the working cylinder thrusts the test rig backward. The noise comes not only from the piston, but also from as many as four airbags and seat belt pretensioners deploying simultaneously.
Like any collision impact event, the action takes place in milliseconds. Six to 12 high-speed cameras document the event at rates of 1,000, 3,000 or 10,000 frames per second. The data can show everything from the precise deployment track of an airbag to the interaction between test dummy, seat belt and active restraint system.
The ServoSled (short for servo-hydraulic sled) isn’t the only impressive feature at Washington Township. In the bottom of the building several labs thump, shake and rattle things. Unlike the spacious carpeted lobby or the architectural smoothness of the office atrium, passages down here are narrow and utilitarian. Different labs and test suites crop up at unexpected levels. Included are areas for sled, linear-impactor and out-of-position testing; dynamic testing that includes a 35-mile-per-hour bungee sled decelerator used to test seat belts and side-impact airbag systems; and a seat-belt reliability lab.
“Testing and simulation is a highly technical area, and we bring our customers the best possible safety evaluations. Our facilities are an investment in validating the future of occupant safety. We’re not just testing restraints, we’re simulating those restraints’ performance in the vehicle environment”, says Steven J. Peterson, Vice President Engineering, North America Region, Global Systems.