Biomechanics of 4-point seat belt systems in frontal impacts.

Author(s)
Rouhana, S.W. Bedewi, P.G. Kankanala, S.V. Prasad, P. Zwolinski, J.J. Meduvsky, A.G. Rupp, J.D. Jeffreys, T.A. & Schneider, L.W.
Year
Abstract

The biomechanical behavior of 4-point seat belt systems was investigated through MADYMO modeling. dummy tests and post mortem human subject tests. This study was conducted to assess the effect of 4-point seat belts on the risk of thoracic injury in frontal impacts. to evaluate the ability to prevent submarining under the lap belt using 4-point seat belts. and to examine whether 4-point belts may induce injuries not typically observed with 3-point seat belts. The performance of two types of 4-point seat belts was compared with that of a pretensioned, load-limited, 3-point seat belt. A 3- point belt with an extra shoulder belt that "crisscrossed" the chest (X4) appeared to add constraint to the torso and increased chest deflection and injury risk. Harness style shoulder belts (V4) loaded the body in a different biomechanical manner than 3-point and X4 belts. The V 4 belt appeared to shift load to the clavicles and pelvis and to reduce traction of the shoulder belt across the chest, resulting in a reduction in chest deflection by a factor of two. This is associated with a 5 to 500-fold reduction in thoracic injury risk, depending on whether one assumes 4-point belts apply concentrated or distributed load. In four of six post mortem human subjects restrained by V4 belts during 40 km/h sled tests. chest compression was zero or negative and rib fractures were nearly eliminated. Submarining was not observed in any test with post mortem human subjects. Though lumbar. sacral and pelvic injuries were noted. they are believed to be due to the artificial restraint environment (no knee bolsters. instrument panels. steering systems or airbags). While they show significant potential to reduce thoracic injury risk. there are still many issues to be resolved before 4-point belts can be considered for production vehicles. These issues include, among others, potential effects on hard and soft neck tissues, of interaction with inboard shoulder belts in farside impacts and potential effects on the fetus of latch/buckle junctions at the centerline of pregnant occupants. Work continues at Ford Motor Company to resolve these issues. (Author/publisher)

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Publication

Library number
20042032 q ST (In: ST 20042032 [electronic version only])
Source

In: Stapp Car Crash Journal Volume 47 : papers presented at the 47th Stapp Car Crash Conference, San Diego, California, USA, October 2003, Technical Paper 2003-22-0017, p. 367-399, 46 ref.

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