Evaluating low-speed rear-end impact severity and resultant occupant stress parameters

Automotive Systems Analysis, Inc. (ASA) and Lowell Hicks, Inc. (LHI) have developed a ground-up set of sensor instrumentation and recording method to document vehicle-artifact/occupant-stress parameters occurring from a continuing series of low-speed rear-end multi-vehicle impact tests (approximately 2 to 8 MPH). This work has four goal areas: 1) calculate impacted vehicle (TARGET) barrier equivalent velocity (BEV) from isolator Artifacts; 2) correlate calculated BEV' to occupant stress; 3) calibrate injury potential of occupant stress impulse; 4) compare occupant stress with everyday volunteer activities. The test collision series now includes several different vehicle pairs with varying impact/escape speeds, weight ratios, and parallel parameters from a driver side manikin and passenger side volunteer. Observable physical vehicle isolator artifacts (piston stroke scrapes) were compared with computer-recorded linear sensor time traces, and these data were fitted to a 'calculated BEV' worksheet/algorithm. The worksheet/algorithm method shown here was found to be reasonably repeatable, per vehicle model and series tested. Next, manikin and volunteer occupant stress data, measured along with TARGET vehicle BEVs, were charted and compared with injury-threshold-impulse criteria referenced in the literature. Lastly, the occupant-stress impulses were compared with sample stress impulses for various volunteer physical activities, as a practical calibration of vehicle occupant stress.