Impact Dynamics of Unrestrained, Lap Belted, and Lap and Diagonal Chest Belted Vehicle Occupants
A comparison is presented of the forces, accelerations, and kinematics of an anthropomorphic dummy for identical sled impacts for unrestrained, lap belted, and lap and diagonal chest restrained conditions. Biaxial accelerometers were mounted in the head, chest, and on the proximal end of the femur to obtain the accelerations during the impacts. Seat belt load cells were put in series with the belts at each anchor point. Biaxial load cells were positioned to be impacted by the head, chest, and each knee for the unrestrained condition and by the head and chest for the lap belted configuration. For the lap and diagonal chest restrained condition these load cells were not used. Impacts of 10 and 20 miles per hour were made with sled stopping distance of 4 and 9 inches, respectively.
At 20 miles per hour the head struck with a force of 1580 pounds in the unrestrained mode, 600 pounds with the lap belt, and did not hit with the lap and shoulder harness. The corresponding A-P head accelerations were 80, 67, and 45 G's. The total lap belt load was 3500 pounds for the lap belt only. With the lap and cross chest combination the lap belt load was 2260 pounds and the cross chest belt load was 2245 pounds for a total load of 4505 pounds. Displacements of the hip, shoulder, and head were measured from the high speed movies and are presented graphically.