Investigations on the belt-to-pelvis interaction in case of submarining

This study focuses on the phenomenon of lap belt slip on the iliac spines of the pelvis, commonly named "submarining". The first objective was to compare the interaction between the pelvis and the lap belt for both dummies and Post Mortem Human Subjects (PMHS). The second objective was to identify parameters influencing the lap belt hooking by the pelvis. For that purpose, a hydraulic test device was developed in order to impose the tension and kinematics of the lap belt such that they mimic what occurs in frontal car crashes. The pelvis was firmly fixed on the frame of this sub-system test-rig, while the belt anchorages were mobile. Fourteen tests on four Post-Mortem Human Subjects (PMHS) and fifteen tests on the THOR NT, Hybrid III 50th and Hybrid III 95th percentile dummies were carried out. The belt tension was kept constant while a dynamic rotation was imposed on the belt anchorages. The test results show that, in the tests where submarining occurred, the belt angle relative to the pelvis was systematically greater for the pelves of dummies than for those of PMHS. An increase in the belt tension resulted in a greater submarining angle for both dummies and PMHS. The pelvis and abdomen stiffnesses were observed to be similar for the PMHS and the THOR NT dummy while significantly lower for the Hybrid III dummies.