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Citation
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Bohman K, Fågelberg E, Jakobsson L. 27th International Technical Conference on the Enhanced Safety of Vehicles (ESV); April 3-6, 2023; Abstract #: 23-0300, pp. 16p. Washington, DC USA: US National Highway Traffic Safety Administration, 2023 open access. |
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Abstract
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27th International Technical Conference on the Enhanced Safety of Vehicles (ESV): Enhanced and Equitable Vehicle Safety for All: Toward the Next 50 Years
https://www-esv.nhtsa.dot.gov/Proceedings/27/27ESV-000300.pdf
Car occupants may choose a wide range of sitting postures, including rearward rotation and forward excursion of the pelvis, through slouching. The overall objective of the study was to contribute to the understanding of restraint interaction, as a function of pelvis orientation and lumbar spine posture. Specifically, the aim was to investigate kinematics of and loading to the occupant in frontal impacts by comparing slouched and upright sitting postures using state-of-the-art restraints.
A human body model (HBM) of a mid-sized male, the SAFER HBM, was restrained in a simulation model of the rear seat of a large passenger car and exposed to a full frontal 50 km/h impact. Three different sitting postures, with constant seat backrest angle were included; a nominal upright sitting posture and two slouched sitting postures, representing moderate and extreme slouching, respectively. The position of the seat in front of the occupant was varied to the mid-track position and the most forward-track position, respectively, to allow for different knee-interaction.
When the front seat was in a mid-track position, submarining did not occur in any of the slouched postures, while partial submarining occurred for the extreme slouched posture with the front seat in the most forward-track position in the model.
During the impact, both slouched postures of the HBM resulted in less torso pitch compared to the nominal posture. The shoulder belt moved up the sternum to a higher extent in the slouched postures, leading to less balanced kinematics with the pelvis moving forward and the upper torso held back by the shoulder belt, contributing to the less torso pitch. These changes in kinematics for the slouched postures resulted in higher lumbar spine compression and lower chest loading, relative to the nominal posture.
In summary, slouched sitting postures affect occupant kinematics and loadings in a frontal impact. By exploring variations in sitting posture in terms of slouching using a HBM, knowledge can be gained in understanding the mechanisms of submarining and lumbar spine loading. These findings are relevant for sitting postures in conventional cars today, in addition to a wider range of sitting postures as a result of future seat developments.
Keywords: sitting posture, slouching, HBM, rear seat, submarining, pelvis orientation |