Facilities

The VTTI Crash Sled Lab houses an impact laboratory along with a high-speed biplane X-ray suite. The centerpiece of this lab is a 1.4-meganewton ServoSled System crash sled manufactured by Seattle Safety. This crash sled has unique capabilities in high-rate impact testing and imaging and is used primarily to study transportation-related trauma. Although the sled is often used for basic research, more applied studies are conducted by fastening reinforced vehicle structures, or “bucks,” to the deck of the sled, which can accommodate payloads of up to 2500 kg. The bucks are used to evaluate vehicle interior components and restraint systems. The sled starts from rest and is pneumatically driven (maximum of 20 MPa) to the desired speed while following a prescribed acceleration pulse. The pulse is shaped using a hydraulic braking system with high-frequency (500 Hz), closed-loop control of acceleration and brake pressure. The acceleration pulse is selected to mimic the crash performance of a specific vehicle or other impact event, and the pulse is quickly and easily modified and programmed to suit. The ServoSled can provide large acceleration late in an event and is capable of producing bipolar acceleration pulses. Frontal-, rear-, and side-impact car crashes can be simulated using human surrogates, including crash dummies. More than 200 transducer channels can be collected using onboard signal conditioning and data acquisition hardware. Multiple high-speed video cameras positioned both off and on the sled are used to capture event kinematics. The ServoSled System is capable of delivering 475,000 N-m, which translates to a maximum 90 kph and 93 g (20 g/ms) within a 2-m driving stroke. At full payload, the sled can achieve 57 kph and 37 g. This crash sled is helping Virginia Tech to better understand injury mechanisms and develop mitigation schemes and protection systems.