爆炸冲击波作用下颅脑损伤机理的数值模拟研究

爆炸引起的颅脑损伤已经成为现代战场单兵的主要致伤形式，而相关的致伤机理尚未完全阐明。本文中，针对头部在爆炸冲击波作用下的动态响应及相关致伤机理进行了数值模拟研究。首先，基于颅脑的核磁共振切片建立了人体头部三维数值模型，该模型真实地反映了颅脑的生理特征与细节构造；利用该模型对人体头部碰撞实验进行数值模拟，模拟结果与实验结果吻合良好，验证了头部模型的有效性。在此基础上，基于欧拉-拉格朗日耦合(Euler-Lagrangian coupling method，CEL)方法发展了爆炸冲击波-头部流固耦合模型，对头部受到爆炸冲击波正面冲击工况进行了数值模拟，分别从流场压力分布、脑组织压力、颅骨变形与加速度等方面对头部动态响应过程进行了分析。爆炸冲击波峰值压力在流固耦合作用下增大为入射波的3.5倍，致使受到直接冲击处的颅骨与脑组织发生高频振动，相应的振动频率高达8 kHz，这与碰撞载荷下的脑组织动态响应是完全不同的。同时，该处颅骨的局部弯曲变形会沿着颅骨进行“传播”，影响着整个颅骨的变化构型，从而决定了脑组织压力与损伤的演化过程。

Numerical simulation of the mechanism of traumatic brain injury induced by blast shock waves

Blast-induced traumatic brain injury (b-TBI) is a signature injury in the current military conflicts. However, the relevant mechanism of injury has not been fully elucidated. In this paper, numerical simulation study is carried out to investigate the dynamic response of brain injury mechanics during the blast loading. Firtstly, the 3D numerical head model is established based on magnetic resonance imaging (MRI) of the human head, whose physiological characteristics and detailed structures are included. The numerical model is adopted to simulate the head collision and the results are in good agreement with the experimental data, demonstrating the validity of the numerical model. Based on the coupled Eulerian-Lagrangian (CEL) theory, a fluid-solid coupling model of explosive shock wave-head is developed. The coupled model is used to simulate the situation of head subjected to frontal impacts by explosion shock wave. The dynamic response of the head is analyzed from the pressure distribution of flow field, brain pressure, skull deformation and acceleration. The peak pressure of explosion shock wave increases 3.5 times as much as that of incident wave under fluid-structure interaction, resulting in high-frequency vibration of skull and brain tissue at the site of direct shock. The corresponding vibration frequency is as high as 8 kHz, which is completely different from the dynamic response of brain tissue under head collision. At the same time, the local bending deformation will “propagate” along the skull, affecting the whole skull configuration, which determines the evolution process of brain tissue pressure and injury.