Assessment of an Innovative Seatbelt with Independent Control of the Shoulder and Lap Portions Using THOR Tests, the THUMS Model and PMHS Tests

Journal article, 2016

Objectives: What are the potential chest injury benefits and influence on occupant kinematics of a belt system with independent control of the shoulder and lap portions.

Methods: This paper investigates the kinematics and dynamics of human surrogates in 35 km/h impacts with two different restraints: a pretensioning (PT), force-limiting (FL) seat belt, a reference belt system, and a concept design with a split buckle consisting (SB) of two separate shoulder and lap belt bands. The study combines mathematical simulations with the THOR dummy and THUMS human body model, and mechanical tests with the THOR dummy and two PMHS tests of similar age (39 and 42 years) and anthropometry (62 kg, 181 cm vs. 60 kg, 171.5 cm). The test setup consisted of a rigid metallic frame representing a standard seating position of a right front passenger. The THOR dummy model predictions were compared to the mechanical THOR dummy test results. The THUMS predicted number of fractured ribs were compared to the number of fractured ribs in the PMHS.

Results: THOR sled tests showed that the SB seat belt system decreased chest deflection significantly without increasing the forward displacement of the head. The THOR model and the THOR physical dummy predicted a 13mm and 7mm reduction in peak chest deflection respectively. Peak diagonal belt force in the mechanical test with the reference belt was 5582N while the predicted force was 4770N. The THOR model also predicted lower belt forces with the SB system than the ones observed in the tests (5606N vs. 6085N). THUMS predicted somewhat increased head displacement for the SB system compared to the reference system. Peak diagonal force with the reference belt was 4000N and for the SB system it was 5200N. The PMHS test with the SB belt resulted in improved kinematics and in a smaller number of rib fractures (2 vs. 5 fractures) compared to the reference belt.

Conclusion: Concepts for a belt system that can reduce the load on the chest of the occupant in a crash and thereby reduce the number of injured occupants, in particular elderly, was proposed.