Recent field accident statistical studies dealing with injury risk assessment of rear seated children in rear impacts indicated a doubling of AIS 2+ injuries when front seats deformed, and a 61 percent increase in fatal injury for rear-seated children, as compared to front-seated children, in rear impacts. Several interrelated factors, which influence child injury risk in rear impacts, were not evaluated in these field accident statistical studies. These factors include: rear-impact severity levels; front occupant sizes; front seat strength variations and protection levels; vehicle type; (i.e. minivan, sedan, etc.); rear child sizes; and, rear child restraint types. This current study uses an experimental “multi-variable” crash test approach, and “inferred statistical” methodology, to scientifically evaluate the several key factors that effect rear child injury risk in rear impacts. This “multi-variable” methodology was previously utilized by the authors for study of front-seated adult injury risk assessment. Various sizes of rear child surrogates (i.e. 6 month-old up to the 6 year-old Hybrid III size), located behind different sizes of front adult surrogates (i.e. small 50kg female up to larger male surrogates ballasted to 110kg) seated in different strength front seats, were dynamically tested at rear-impact severity speed change levels ranging from about 20 to 50 kph. Both sled-body-buck and full vehicle crash tests were used in this study. Front seat strength levels ranged from the weaker 3.2kN level for single recliner (SR) seats, without belts attached to the seatback, up to the stronger belt-integrated seat (BIS) levels of about 14.7kN. The study results demonstrate that, even absent rear crush intrusion, the easily deforming SR front seats pose a high risk of injury to the rear child, regardless of vehicle type, in contrast to stronger and safer BIS designs.
SIMULATION OF VEHICULAR FRONTAL CRASH-TEST
