Numerical analysis of driver thoracolumbar spine response in frontal crash reconstruction

Ye, Xin; Jones, Derek; Gaewsky, James; Miller, Logan; Stitzel, Joel; Weaver, Ashley

Affiliations

¹Wake Forest University School of Medicine

²Virginia Tech-Wake Forest University Center for Injury Biomechanics

Abstract

This study aimed to reconstruct 11 motor vehicle crashes (six with thoracolumbar fractures and five without thoracolumbar fractures), and analyze the fracture mechanism, fracture pattern, associated vehicle parameters and driver attributes affecting fracture risk. Eleven frontal crashes were reconstructed with a finite element simplified vehicle model (SVM). The SVM was tuned to each case vehicle and the Total HUman Model for Safety (THUMS) v4.01 was scaled and positioned in a baseline configuration to mimic the pre-crash driver posture. For the six thoracolumbar fracture cases, 120 simulations to quantify uncertainty and variation were performed using a Latin Hypercube Design of Experiments (DOE) to vary: seat track position, seatback angle, steering column angle, steering column position, and D-ring height. Vertebral loads and bending moments were analyzed. Maximum principal strain and stress were collected in the vertebral cortical and trabecular bone. DOE data were fit to regression models to examine occupant positioning and thoracolumbar response correlations. Of the 11 cases, both the vertebral compression force and bending moment progressively increased from superior to inferior vertebrae. Two thoracic spine fracture cases had higher compression force and bending moment across all thoracic vertebral levels, compared to nine cases without thoracic spine fractures (force: 1200.6 vs. 640.8 N; moment: 13.7 vs. 9.2 Nm). While there was no apparent difference in bending moment at the L1-L2 vertebrae, lumbar fracture cases exhibited higher vertebral bending moments in L3-L4 (fracture/non-fracture: 45.7 vs. 33.8 Nm). A rearward seat track position and reclined seatback increased the thoracic spine bending moment by 111-329%. A more reclined seatback increased the lumbar force and bending moment by 16-165% and 67- 172%, respectively. This study provided a computational framework for assessing thoracolumbar fractures, and also quantified the effect of pre-crash driver posture on fracture risk. Results aid in the understanding of factors contributing to thoracolumbar fractures.

Links

URL: http://ibrc.osu.edu/wp-content/uploads/2018/05/Ye_manuscript.pdf

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