Department of Biomedical Engineering, Duke University, 136 Hudson Hall, Box 90281, Durham, NC 27708, USA.
Ann Biomed Eng. 2012 Jul;40(7):1530-44. doi: 10.1007/s10439-012-0519-2.
Blast-related traumatic brain injury is the most prevalent injury for combat personnel seen in the current conflicts in Iraq and Afghanistan, yet as a research community,we still do not fully understand the detailed etiology and pathology of this injury. Finite element (FE) modeling is well suited for studying the mechanical response of the head and brain to blast loading. This paper details the development of a FE head and brain model for blast simulation by examining both the dilatational and deviatoric response of the brain as potential injury mechanisms. The levels of blast exposure simulated ranged from 50 to 1000 kPa peak incident overpressure and 1–8 ms in positive-phase duration, and were comparable to real-world blast events. The frontal portion of the brain had the highest pressures corresponding to the location of initial impact, and peak pressure attenuated by 40–60% as the wave propagated from the frontal to the occipital lobe. Predicted brain pressures were primarily dependent on the peak overpressure of the impinging blast wave, and the highest predicted brain pressures were 30%less than the reflected pressure at the surface of blast impact. Predicted shear strain was highest at the interface between the brain and the CSF. Strain magnitude was largely dependent on the impulse of the blast, and primarily caused by the radial coupling between the brain and deforming skull.The largest predicted strains were generally less than 10%,and occurred after the shock wave passed through the head.For blasts with high impulses, CSF cavitation had a large role in increasing strain levels in the cerebral cortex and periventricular tissues by decoupling the brain from the skull. Relating the results of this study with recent experimental blast testing suggest that a rate-dependent strain-based tissue injury mechanism is the source primary blast TBI.
爆炸相关的创伤性脑损伤是目前在伊拉克和阿富汗冲突中战斗人员最常见的损伤，但作为一个研究团体，我们仍然不完全了解这种损伤的详细病因和病理学。有限元（FE）建模非常适合研究头部和大脑对爆炸载荷的力学响应。本文通过研究大脑的膨胀和偏斜响应作为潜在的损伤机制，详细介绍了一种用于爆炸模拟的 FE 头和脑模型的开发。模拟的爆炸暴露水平范围从 50 到 1000kPa 峰值入射超压和 1-8ms 的正相持续时间，与实际的爆炸事件相当。大脑的前部区域具有与初始冲击位置相对应的最高压力，并且当波从额部传播到枕部时，峰值压力衰减了 40-60%。预测的脑压主要取决于冲击爆炸波的峰值超压，并且预测的最高脑压比冲击表面的反射压力低 30%。预测的剪切应变在脑和 CSF 之间的界面处最高。应变幅度在很大程度上取决于爆炸的脉冲，主要是由于大脑和变形颅骨之间的径向耦合引起的。最大的预测应变通常小于 10%，并且在冲击波穿过头部后发生。对于具有高脉冲的爆炸，CSF 空化通过使大脑与颅骨解耦，在大脑皮层和脑室周围组织中产生较大的应变水平，在大脑皮层和脑室周围组织中产生较大的应变水平。将本研究的结果与最近的实验爆炸测试相关联表明，基于应变的组织损伤机制是原发性爆炸性脑外伤的主要原因。
