Takhounts Erik G, Ridella Stephen A, Hasija Vikas, Tannous Rabih E, Campbell J Quinn, Malone Dan, Danelson Kerry, Stitzel Joel, Rowson Steve, Duma Stefan
U.S. Dept. of Transportation, National Highway Traffic Safety Administration, NVS-323, W46-471. 1200 New Jersey Avenue, SE, Washington, DC 20590, USA.
Stapp Car Crash J. 2008 Nov;52:1-31. doi: 10.4271/2008-22-0001.
The objective of this study was to investigate potential for traumatic brain injuries (TBI) using a newly developed, geometrically detailed, finite element head model (FEHM) within the concept of a simulated injury monitor (SIMon). The new FEHM is comprised of several parts: cerebrum, cerebellum, falx, tentorium, combined pia-arachnoid complex (PAC) with cerebro-spinal fluid (CSF), ventricles, brainstem, and parasagittal blood vessels. The model's topology was derived from human computer tomography (CT) scans and then uniformly scaled such that the mass of the brain represents the mass of a 50th percentile male's brain (1.5 kg) with the total head mass of 4.5 kg. The topology of the model was then compared to the preliminary data on the average topology derived from Procrustes shape analysis of 59 individuals. Material properties of the various parts were assigned based on the latest experimental data. After rigorous validation of the model using neutral density targets (NDT) and pressure data, the stability of FEHM was tested by loading it simultaneously with translational (up to 400 g) combined with rotational (up to 24,000 rad/s2) acceleration pulses in both sagittal and coronal planes. Injury criteria were established in the manner shown in Takhounts et al. (2003a). After thorough validation and injury criteria establishment (cumulative strain damage measure--CSDM for diffuse axonal injuries (DAI), relative motion damage measure--RMDM for acute subdural hematoma (ASDH), and dilatational damage measure--DDM for contusions and focal lesions), the model was used in investigation of mild TBI cases in living humans based on a set of head impact data taken from American football players at the collegiate level. It was found that CSDM and especially RMDM correlated well with angular acceleration and angular velocity. DDM was close to zero for most impacts due to their mild severity implying that cavitational pressure anywhere in the brain was not reached. Maximum principal strain was found to correlate well with RMDM and angular head kinematic measures. Maximum principal stress didn't correlate with any kinematic measure or injury metric. The model was then used in the investigation of brain injury potential in NHTSA conducted side impact tests. It was also used in parametric investigations of various "what if" scenarios, such as side versus frontal impact, to establish a potential link between head kinematics and injury outcomes. The new SIMon FEHM offers an advantage over the previous version because it is geometrically more representative of the human head. This advantage, however, is made possible at the expense of additional computational time.
本研究的目的是在模拟损伤监测器（SIMon）的概念框架内，使用新开发的、几何细节丰富的有限元头部模型（FEHM）来研究创伤性脑损伤（TBI）的可能性。新的FEHM由几个部分组成：大脑、小脑、大脑镰、小脑幕、联合软脑膜 - 蛛网膜复合体（PAC）与脑脊液（CSF）、脑室、脑干和矢状旁血管。该模型的拓扑结构源自人体计算机断层扫描（CT）扫描，然后进行统一缩放，以使大脑质量代表第50百分位男性大脑的质量（1.5千克），头部总质量为4.5千克。然后将该模型的拓扑结构与通过对59个人进行普氏形状分析得出的平均拓扑结构的初步数据进行比较。基于最新的实验数据为各个部分分配材料属性。在使用中性密度目标（NDT）和压力数据对模型进行严格验证之后，通过在矢状面和冠状面同时施加平移（高达400g）与旋转（高达24,000rad/s²）加速度脉冲来测试FEHM的稳定性。损伤标准按照Takhounts等人（200）中所示的方式确定。在经过全面验证并确定损伤标准（用于弥漫性轴索损伤（DAI）的累积应变损伤度量 - CSDM、用于急性硬膜下血肿（ASDH）的相对运动损伤度量 - RMDM以及用于挫伤和局灶性病变的膨胀损伤度量 - DDM）之后，该模型基于从大学水平的美国橄榄球运动员获取的一组头部撞击数据，用于研究活体人类的轻度TBI病例。研究发现，CSDM尤其是RMDM与角加速度和角速度具有良好的相关性。由于大多数撞击的严重程度较轻，DDM接近零，这意味着大脑中任何部位都未达到空化压力。发现最大主应变与RMDM和头部角运动学测量具有良好的相关性。最大主应力与任何运动学测量或损伤指标均无相关性。然后该模型被用于美国国家公路交通安全管理局（NHTSA）进行的侧面碰撞试验中的脑损伤可能性研究。它还被用于各种“如果……会怎样”情景的参数研究，例如侧面碰撞与正面碰撞，以建立头部运动学与损伤结果之间的潜在联系。新的SIMon FEHM比之前的版本具有优势，因为它在几何形状上更能代表人类头部。然而，这种优势是以额外的计算时间为代价实现的。
