Effects of seat pan and pelvis angles on the occupant response in a reclined position during a frontal crash

Abstract

Current highly automated vehicle concepts include reclined seat layouts that could allow occupants to relax during the drive. The main objective of this study was to investigate the effects of seat pan and pelvis angles on the kinematics and injury risk of a reclined occupant by numerical simulation of a frontal sled test. The occupant, represented by a detailed 50th percentile male human body model, was positioned on a semi-rigid seat. Three seat pan angles (5, 15, and 25 degrees from the horizontal) were used, all with a seatback angle of 40 degrees from the vertical. Three pelvis angles (60, 70, and 80 degrees from the vertical), representing a nominal and two relaxed sitting positions, were used for each seat pan angle. The model was restrained using a pre-inflated airbag and a three-point seatbelt equipped with a pretensioner and a load limiter before being subjected to two frontal crash pulses. Both model kinematic response and predicted injury risk were affected by the seat pan and the pelvis angles in a reclined seatback position. Submarining occurrence and injury risk increased with lower seat pan angle, higher pelvis angle, and acceleration pulse severity. In some cases (in particular for a 15 degrees seat pan), a small variation in seat pan or pelvis angle resulted in large differences in terms of kinematics and predicted injury. This study highlights the potential effects of the seat pan and pelvis angles for reclined occupant protection. These parameters should be assessed experimentally with volunteers to determine which combinations are most likely to be adopted for comfort and with post mortem human surrogates to confirm their significance during impact and to provide data for model validation. The sled and restraint models used in this study are provided under an open-source license to facilitate further comparisons.

Personalization of human body models and beyond via image registration

“…Finite element (FE) human body models (HBMs) are becoming increasingly important numerical tools in vehicle safety for understanding injury mechanisms and developing prevention strategies (Östh et al, 2015;Boyle et al, 2019;Hu et al, 2019;Jakobsson et al, 2019;Pipkorn et al, 2019;Boyle et al, 2020;Hwang et al, 2020;Tang et al, 2020;Grebonval et al, 2021;Leledakis et al, 2021;Larsson et al, 2022;Bohman et al, 2022;Booth et al, 2022;Corrales et al, 2022;Erlinger et al, 2022;Mishra et al, 2022;Piqueras et al, 2022;Putra et al, 2022;Östh et al, 2022). HBMs have advantages over crash test dummies, such as representing varying loading directions, different anthropometries and sex, and muscle tonus (Jakobsson et al, 2019).…”

Assessment of the sensitivity of thoracic injury criteria to subject-specific characteristics using human body models

“…In addition, Mendoza-Vazquez et al (2015) also found that injury metrics based on multi-point measurements (DcTHOR and Cmax) were less sensitive to variations in the material properties of the FE-HBM, making these metrics particularly suitable to be used with FE models. Current studies show multiple examples of the application of deformation-based criteria to the prediction of chest injuries using FE-HBM such as Brolin and Wass (2016) , which used DcTHOR and Dmax metrics with the THUMS model for the assessment of the injury protection provided by a safety-vest in equestrian riders, or Grébonval et al (2021) , which used the Cmax and PC Score to compare the thoracic injury risk predicted by the GHBMC HBM and the THOR ATD in frontal impacts in reclined occupant positions.…”

Influence of a Passenger Position Seating on Recline Seat on a Head Injury during a Frontal Crash

“…The most severe and commonly investigated factor occurring in a frontal crash with a reclined seat is submarining-i.e., the occupant's hips sliding under the lap belt, restraining the body at the abdomen [12][13][14]. Submarining causes severe injuries to the lumbar spine and internal organs [15][16][17][18][19]. Accident data analysis shows that the submarining phenomenon is the reason for many fatalities and serious injuries during a frontal impact [20][21][22].…”