The occupant motion in rear impacts that is associated with Whiplash Associated Disorders (WAD) can be broken into four phases, each representing a distinct possible source for injury: retraction, extension, rebound and protraction. Injury criteria such as NIC and N(sub)km have been proposed to evaluate the injury potential of these mechanisms. Key vehicle design factors contributing to WAD motion include head restraint backset and height,seat stiffness, and vehicle structural characteristics. The hypothesis of this study was that different WAD phases would show different levels of sensitivity to vehicle design factors. A detailed 50th percentile male model with a biofidelic neck was used in a 100-run Monte Carlo analysis of a rear impact, varying design factors across the values documented in literature. Total energy was held constant and Delta V was 10 kph. Vehicle stiffness had strong influence on the retraction (70%), rebound (43%) and protraction (47%) phases. Backset (the initial distance from occupant head to vehicle headrest) demonstrated a strong influence on the extension (49%) and rebound (39%) phases. For design rating and WAD protection, it is important to view the vehicle as a system and not just a single design variable. For the covering abstract see ITRD E141807.
Samenvatting