Kinematics and dynamics of the pelvis in the process of submarining using PMHS sled tests

This study focused on a better understanding and characterization of the submarining phenomenon that occurs in frontal crashes when the lap belt slides over the anterior superi or iliac spine. Submarining is the consequence of the pelvis kinematics relative to the lap belt, driven by the equilibrium of forces and moments applied to the pelvis. The study had two primary purposes; the first was to provide new PMHS data in submarining test configurations, the second was to investigate the Hybrid II and Hybrid III dummies biofidelity regarding submarining. Several Post Mortem Human Subject (PMHS) studies have been published on this subject. However, the lack of information about the occupant initial positioning and the use of car seats make it difficult to reconstruct these tests. Furthermore, the two dummies are rarely compared to PMHS in submarining test configurations. A fifteen frontal sled test campaign was carried out on two Anthropomorphic Test Devices (ATDs) and nine PMHS. The test environment was designed to be reproducible. It consisted of a rigid seat, a 2-poi nts shoulder belt and a 2-points lap belt instrumented to record their 3D forces at anchorage. The subjects were instrumented with angular sensors at the sacrum, T1 and T12 levels to record their initial angles. Kinematics was measured at these three levels by means of three accelerometers and angular velocity sensors. A PMHS positioning procedure was developed to ensure repeatability. A pre-test was performed on each subject to characterize its lumbar spine static behavior. All the subjects were CT-scanned from head to toe prior to the test. The campaign was divided into three test configurations leading to different surrogates' interaction with the environment and different kinematics. This resulted in a wider range of behaviors for the dummies evaluation. The deceleration pulse, initial lap belt angle, lap belt slack, seat pan angle and footrest position varied. The Hybrid II and Hybrid III dummies and three PMHS were tested in each configuration. Forces and kinematics time history corridors based on the PMHS responses are provided for each configuration. The dummies' responses are evaluated against these targets. For the first configuration (40 km/h), the peak lap belt tension for both sides was between 3,000 N and 6,385 N for the three PMHS while it was around 4,700 N and 6,200 N in average for Hybrid II and Hybrid III respectively. The maximum pelvic rotation ranged from 41° to 80° for the PMHS and reached approximately 45° for the two dummies. For the other two configurations (50 km/h), the peak lap belt tension varied from 3,660 N to 7,180 N for the PMHS and was between 5,400 N and 6,100 N for Hybrid II and between 7,145 N and 7,900 N for Hybrid III. The maximum pelvic rotation ranged from 43° to 73° for the PMHS, while it reached approximately 54° and 46° for Hybrid II and Hybrid III respectively.