The Role of Three-Point Restraints for Occupants in Moderate Severity Frontal Collisions 2022-01-0845

Field accident data and vehicle crash and sled testing indicate that occupant kinematics, loading, and associated injury risk generally increase with crash severity. Further, these data demonstrate that the use of restraints, such as three-point belts, provides mitigation of kinematics and reduction in loading and injury potential. This study evaluated the role of seat belts in controlling occupant kinematics and reducing occupant loading in moderate severity frontal collisions. Frontal tests with belted and unbelted anthropomorphic test devices (ATDs) in the driver and right front passenger seats were performed at velocity changes (delta-Vs) of approximately 19 kph (12 mph) and 32 kph (20 mph) without airbag deployment. At the lower-moderate severity (19 kph), motion of the belted ATDs was primarily arrested by seat belt engagement, while motion of the unbelted ATDs was primarily arrested by interaction with forward vehicle structures. Occupant loading and injury risk was generally lower with proper belt use as compared to an unbelted occupant. At the higher-moderate severity (32 kph), both the belted and unbelted ATDs demonstrated lower extremity engagement with forward vehicle structures, though femur compression loads were substantially attenuated for the belted ATDs. With belt use, the pelvis and torso were restrained by the seat belt which reduced overall forward torso and head excursion. As the neck flexed due to torso restraint, increased lower neck flexion was observed relative to the unbelted ATDs, though upper neck flexion remained greater for the unbelted ATD. In the higher-moderate severity test, neck flexion about the torso restraint resulted in the belted driver ATD’s head contacting the steering wheel. The unbelted ATDs moved forward in an unrestrained fashion until motion was arrested via contact with forward vehicle structures, resulting in generally higher occupant loading in comparison to their belted counterparts. These findings support the effectiveness of seat belts in controlling occupant kinematics and reducing injury potential in moderate severity frontal collisions.