Numerical study on dynamic mechanism of brain volume and shear deformation under blast loading

Numerical study on dynamic mechanism of brain volume and shear deformation under blast loading

Zhijie

Li1·Zhibo

Du1·Xiaochuan Luo1·Dongyang

You1·Zhanli Chu1·Shaowu

Liu1·Jian Ning1·Yue

Cheng1·Chengcheng

Kang2·Ce Yang3·Zhuo Zhuang1

【摘 要】Abstract Blast-induced traumatic brain injury(b-TBI)is a kind of significant injury to soldiers in the current military conflicts.However,the mechanism of b-TBI has not been well understood, and even there are some contradictory conclusions. It is crucial to reveal the dynamic mechanism of brain volume and shear deformations under blast loading for better understanding of b-TBI.In this paper,the numerical simulation method is adopted to carry out comprehensive and in-depth researches on this issue for the first time.Based on the coupled Eulerian-Lagrangian method,the fluid-structure coupling model of the blast wave and human head is developed to simulate two situations,namely the head subjected to the frontal and lateral impacts.The simulation results are analyzed to obtain the underlying dynamic mechanisms of brain deformation.The brain volume deformation is dominated by the local bending vibration of the skull,and the corresponding frequency for the forehead skull under the frontal impact and the lateral skull faced to the lateral impact is as high as 8 kHz and 5 kHz,respectively.This leads to the high-frequency fluctuation of brain pressure and the large pressure

gradient along the skull,totally different from the dynamic response of brain under head collisions.While the brain shear deformation mainly depends on the relative tangential displacement between the skull and brain and the anatomical structure of inner skull,being not related to the brain pressure and its gradient.By further comparing the medical statistics,it is inferred that diffuse axonal injury and brain contusion,the two most common types of b-TBI,are mainly attributed to brain shear deformations.And the von Mises stress can be adopted as the indicator for these two brain injuries.This study can provide theoretical guidance for the diagnosis of b-TBI and the development of protective equipment.

【期刊名称】《力学学报：英文版》 【年(卷),期】2019(035)005 【总页数】16

【关键词】Keywords Blast-induced traumatic brain injury·Numerical head model·Fluid-structure coupling model·Diffuse axonal injury·Brain contusion

Received:1 March 2019/Revised:10 April 2019/Accepted:15 April 2019/Published online:21 June 2019

?The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag GmbH Germany,part of Springer Nature 2019,corrected publication 2019

?Xiaochuan You youxiaochuan@tsinghua.edu.cn ?Zhanli Liu liuzhanli@tsinghua.edu.cn

1 School of Aerospace Engineering,Tsinghua University,Beijing 100084,China 2

School

of

Materials

Science

and

Engineering,Tsinghua

University,Beijing 100084,China

3 Daping Hospital,Army Medical University,Chongqing 400038,China

1 Introduction

According to the analysis of relevant reports about the injuries in modern warfare,the number of military personnel suffering from traumatic brain injury(TBI)in the US military is 20%of the total number of people in service,and the brain injury induced by blast waves accounts for 40%-60%[1]. The blast-induced traumatic brain injury (b-TBI) can be divided into four broad categories[2-4]:(1)primary blast injury because of the blast wave directly propagating through brain tissue,(2)secondary blast injury due to the interaction with fragments or shrapnel,(3)tertiary blast injury induced by the impact between body and environmental structures,and(4)quaternary blast injury caused by heat,electromagnetic pulses or toxic detonation products.

In view of primary blast injury,many scholars have carried out a lot of relevant research works and proposed a variety of injury mechanisms.Garcia-Gonzalez et al.[5]carried out the animal experiments