Abstract:
Vehicle rollover accidents frequently result in occupant head-roof interaction, which
transfers the load to the spinal column and induces severe injuries. This study aims to
evaluate the response of lower lumbar spinal intervertebral disc damage and enhance
passive safety mechanisms in minibus rollover accidents. After an in-depth studying of
the upper body biomechanics of the occupant, a hybrid model that incorporated finite
element analysis and lumped parameter model was developed and validated with
previous works of literature. A minibus rollover accident scenario is mathematically
computed, and the whole configuration analysis is numerically conducted using LSDYNA software. With given criteria of displacement increment 0.582mm, pressure
1.87MPa, and Von-Mise’s stress 1.27MPa is recorded and damage of the intervertebral
disc with a roof intrusion 0.455m/s
2
acceleration. In addition to a variety of passive
safety features, padding materials are introduced to the roof body components to
mitigate intervertebral disc injury. The mechanical properties of the utilized padding
materials are numerically validated with other work. CONFOR green pad shows the
best performance followed by polyurethane foam, Micro-agglomerated cork, Dax, and
IMPAXX. Which dramatically reduced intervertebral disc damage by limiting
displacement by 59.27%, 57.2% of pressure drop, and lowering Von-Mise's stress by
66% compared with no padding. Furthermore, this research investigated the
bioinspired geometry of the trapezoidal-shaped pad that contributes an intervertebral
disc displacement reduction of 4%, reduced stress by 4.6%, and 3.785% pressure is
dropped. As a result, the incorporation of padding materials in minibus has yielded
promising results in terms of improving the reduction of occupant lower lumbar spinal
intervertebral disc impairment.
Keywords: Padding materials; passive safety; rollover accident; finite element
analysis; bioinspired; biomechanics; hybrid model; LS-DYNA