Investigation on an Injury Criterion Related to Traumatic Brain Injury Primarily Induced by Head Rotation

The high frequency of fatal head injuries is one of the important issues in traffic safety, and Traumatic Brain Injuries (TBIs) without skull fracture account for approximately half of them in both occupant and pedestrian crashes. In order to evaluate vehicle safety performance for TBIs in these crashes using anthropomorphic test dummies (ATDs), a comprehensive injury criterion calculated from the rotational rigid motion of the head is required. While many studies have been conducted to investigate such an injury criterion with a focus on diffuse brain injuries in occupant crashes, there have been only a limited number of studies focusing on pedestrian impacts. The objective of this study is to develop a comprehensive injury criterion based on the rotational rigid body motion of the head suitable for both occupant and pedestrian crashes.

In this study, an injury criterion that correlates with the tissue-level predictors of diffuse brain injuries in both occupant and pedestrian crashes is proposed by incorporating the change of the rotational velocity during a certain maximum time. A mid-sized male human head/brain FE model was used to investigate the correlation between injury criteria based on the rotational rigid body motion of the head and the tissue-level predictors of diffuse brain injuries such as Cumulative Strain Damage Measure (CSDM) and Maximum Principle Strain (MPS) to compare the applicability of the proposed criterion to that of the currently proposed injury criteria.