Analysis of individual variabilities for lumbar and pelvic alignment in highly reclined seating postures and occupant kinematics in a collision

Izumiyama, Tomohiro<sup>1</sup>; Nishida, Norihiro<sup>2</sup>; Yamagata, Hiroki<sup>2</sup>; Asahi, Ryusuke<sup>1</sup>; Chen, Xian<sup>3</sup>; Ohgi, Junji<sup>3</sup>; Sugimoto, Shigeru<sup>1</sup>; Fukushima, Masanobu<sup>1</sup>

Affiliations

¹Vehicle Development Division, Mazda Motor Corporation, Japan

²Department of Orthopaedic Surgery, Yamaguchi University Graduate School of Medicine, Japan

³Department of Mechanical Engineering at Yamaguchi University, Japan

Abstract and keywords

The primary objective of this study was to investigate the effect of the postural change between a normal seating posture and a reclined posture in vehicles by using X-ray to measure individual variabilities of skeletal alignments in a reclined seat. Another objective was to understand the effects of this postural change on injury outcomes. Therefore, human body models representing those individual variabilities were constructed by modifying THUMS ver.4, and occupant kinematics in frontal crashes were analyzed. Three target seating postures were defined, at 24, 35 and 45 degrees. Based on the analysis results of the X-ray data, the lumbar and pelvic alignments of THUMS were modified. Three different reclining angles and skeletal alignment types were compared. At 45 degrees, the forward displacement of whole body and the downward movement of the pelvis were observed. Additionally, the differences in kinematics of the upper body by the different alignment types was also confirmed. Furthermore, more head acceleration, chest rib fractures and lumbar spine stress were observed, as well as a higher risk of submarining. It was found that a reclined posture could significantly affect occupant kinematics and injury outcomes in a collision.

Keywords: Reclined posture; individual variabilities; skeletal alignment; occupant kinematics; submarining

Links

URL: http://www.ircobi.org/wordpress/downloads/irc22/pdf-files/22113.pdf

Cited Works (11)

Year	Entry
2020	Izumiyama T, Nishida N, Iwanaga H, Chen X, Ohgi J, Asahi R, Sugimoto S, Fukushima M. Identification of influential factors for seatbelt kinematics in a collision and analysis of their influence degree to the kinematics. In: Proceedings of the 2020 International IRCOBI Conference on the Biomechanics of Injury. 2020; Munich, Germany.456-469.
2019	Hasija V, Kelkar R, Takhounts EG. Simulation assessment of injury trends for 50th percentile males using potential seating configurations of future automated driving system (ADS) equipped vehicles. In: Proceedings of the 26th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 10-13, 2019; Eindhoven, Netherlands.
2019	Boyle KJ, Reed MP, Zaseck LW, Hu J. A human modelling study on occupant kinematics in highly reclined seats during frontal crashes. In: Proceedings of the 2019 International IRCOBI Conference on the Biomechanics of Injury. September 11-13, 2019; Florence, Italy.282-292.
2011	Kindig M, Lau AG, Kent RW. Biomechanical response of ribs under quasistatic frontal loading. Traffic Inj Prev. August 2011;12(4):377-387.
2015	Schafman MA. Dynamic Structural Properties of Human Ribs in Frontal Loading [Master's thesis]. The Ohio State University; 2015.
2020	Mroz K, Östling M, Richardson R, Kerrigan J, Forman J, Gepner B, Lubbe N, Pipkorn B. Effect of seat and seat belt characteristics on the lumbar spine and pelvis loading of the safer human body model in reclined postures. In: Proceedings of the 2020 International IRCOBI Conference on the Biomechanics of Injury. 2020; Munich, Germany.470-486.
2020	Gepner BD, Rawska K, Kerrigan JR. Occupant response in frontal, oblique and side impacts in highly automated vehicles environment. In: Proceedings of the 2020 International IRCOBI Asia Conference on the Biomechanics of Injury. 2020; Beijing, China.114-117.
2005	Charpail E, Trosseille X, Petit P, Laporte S, Lavaste F, Vallancien G. Characterization of PMHS ribs: a new test methodology. Stapp Car Crash J. 2005;49:183-198. SAE 2005-22-0009.
2020	Gepner BD, Toczyski J, Rawska K, Moreau D, Kerrigan JR. Sensitivity of human body model response relative to the lumbar spine and pelvic tissue formulation. In: Proceedings of the 2020 International IRCOBI Conference on the Biomechanics of Injury. 2020; Munich, Germany.156-168.
2020	Richardson R, Jayathirtha M, Donlon JP, Forman JL, Gepner B, Ostling M, Mroz K, Pipkorn B, Kerrigan JR. Pelvis kinematics and injuries of reclined occupants in frontal impacts. In: Proceedings of the 2020 International IRCOBI Conference on the Biomechanics of Injury. 2020; Munich, Germany.499-515.
2018	Izumiyama T, Nishida N, Iwanaga H, Chen X, Ohgi J, Mori K, Hayashi T, Sakuramoto I, Asahi R, Sugimoto S, Ueno M. The analysis of an individual difference in human skeletal alignment in seated posture and occupant behavior using HBMs. In: Proceedings of the 2018 International IRCOBI Conference on the Biomechanics of Injury. September 12-14, 2018; Athens, Greece.549-560.

Cited By (2)

Year	Entry
2023	Rieger L, Neumann F, Asahi R, Izumiyama T, Draper D, Pipkorn B, Sprenger M, Peldschus S. First target datasets for the consideration of postural variety in FE HBM analysis of the lumbar spine. In: Proceedings of the 2023 International IRCOBI Conference on the Biomechanics of Injury. September 13-165, 2023; Cambridge, United Kingdom.713-714.
2023	Iraeus J, Poojary YN, Jaber L, John J, Davidsson J. A new open-source finite element lumbar spine model, its tuning and validation, and development of a tissue-based injury risk function for compression fractures. In: Proceedings of the 2023 International IRCOBI Conference on the Biomechanics of Injury. September 13-165, 2023; Cambridge, United Kingdom.1048-1072.