An innovative seat belt concept aimed at reducing chest injuries was evaluated by means of mechanical tests and mathematical modelling. The tools used were mechanical THOR dummy, mathematical THOR dummy model, THUMS human body model and (Post Mortem Human Surrogates) PMHS. The potenital chest injury reducing benfits with a innovative seat belt concept relative to a state of the art belt system was evaluated in sled tests. The reference belt system was a state of the art belt system with a pretensioning of 2kN at the retractor, a force limiter of 4.5kN and an outer lapbelt pretensioner with a pretensioning force of 3.5kN. The innovative seat belt concept was consisting of a retractor equipped with a 2kN pretensioner at the retractor, a force limiter of 6kN and two 3.5kN pretensioners at the buckle and outer lap belt anchorage. The belt was split at the buckle and the lower end of the diagonal belt was moved 50mm forward. With the altered belt geometry the load on the lower part of the chest was reduced and the peak chest deflection was reduced relative to a state of the art belt system. In mechanical sled tests with rigid seat and an impact velocity of 35 and 30kph with the THOR dummy peak chest deflection was reduced by 8.0mm compared to a state of the art belt system. In the corresponding sled model with the THOR dummy model peak chest deflection was reduced by 13mm. Head x-displacement was increased by 26mm for the mechanical THOR dummy and 24mm for the THOR dummy model. For the THUMS model pleak chest deflection was reduced by 10mm with the split buckle system.

Generally for the mechanical THOR dummy, the THOR dummy model and the Autoliv THUMS model peak chest deflection was reduced by approximately 8-13mm with the split buckle belt system while only a minor increase in head x-displacement was observed relative to a state of the art belt system.