Assessment of an innovative seat belt with independent control of the shoulder and lap portions using THOR tests, the THUMS model, and PMHS tests

Evaluación de sistemas de retención innovadores

Objectives: The objective of this study was to determine 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 article investigates the kinematics and dynamics of human surrogates in 35 km/h impacts
with 2 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 2 separate shoulder and lap belt bands. The study
combinesmathematical simulations with the THOR dummy and THUMS human body model, andmechanical
tests with the THOR dummy and 2 postmortem human surrogate (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 13- and 7-mm reduction in peak chest deflection, respectively. Peak diagonal belt force in the
mechanical test with the reference belt was 5,582 N and the predicted force was 4,770 N. The THOR model
also predicted lower belt forces with the SB system than observed in the tests (5,606 vs. 6,085 N). THUMS
predicted somewhat increased head displacement for the SB system compared to the reference system.
Peak diagonal force with the reference belt was 4,000 N and for the SB system it was 5,200 N. The PMHS test
with the SB belt resulted in improved kinematics and 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 the elderly, was proposed.