Ji Songbai, Zhao Wei, Li Zhigang, McAllister Thomas W
Thayer School of Engineering, Dartmouth College, Hanover, NH, 03755, USA,
Biomech Model Mechanobiol. 2014 Oct;13(5):1121-36. doi: 10.1007/s10237-014-0562-z. Epub 2014 Mar 9.
Both linear [Formula: see text] and rotational [Formula: see text] accelerations contribute to head impacts on the field in contact sports; however, they are often isolated in injury studies. It is critical to evaluate the feasibility of estimating brain responses using isolated instead of full degrees-of-freedom (DOFs) accelerations. In this study, we investigated the sensitivities of regional brain strain-related responses to resultant [Formula: see text] and [Formula: see text] as well as the relative contributions of these acceleration components to the responses via random sampling and linear regression using parameterized, triangulated head impacts with kinematic variable values based on on-field measurements. Two independently established and validated finite element models of the human head were employed to evaluate model-consistency and dependency in results: the Dartmouth Head Injury Model and Simulated Injury Monitor. For the majority of the brain, volume-weighted regional peak strain, strain rate, and von Mises stress accumulated from the simulation significantly correlated with the product of the magnitude and duration of [Formula: see text], or effectively, the rotational velocity, but not to [Formula: see text]. Responses from [Formula: see text]-only were comparable to the full-DOF counterparts especially when normalized by injury-causing thresholds (e.g., volume fractions of large differences virtually diminished (i.e., [Formula: see text]1 %) at typical difference percentage levels of 1-4 % on average). These model-consistent results support the inclusion of both rotational acceleration magnitude and duration into kinematics-based injury metrics and demonstrate the feasibility of estimating strain-related responses from isolated [Formula: see text] for analyses of strain-induced injury relevant to contact sports without significant loss of accuracy, especially for the cerebrum.
在接触性运动中，线性加速度[公式：见正文]和旋转加速度[公式：见正文]都会导致头部在赛场上受到撞击；然而，在损伤研究中它们常常被单独考虑。评估使用单独的而非全自由度（DOF）加速度来估计大脑反应的可行性至关重要。在本研究中，我们通过基于现场测量的运动学变量值进行参数化三角测量头部撞击，并通过随机抽样和线性回归，研究了区域脑应变相关反应对合成加速度[公式：见正文]和[公式：见正文]的敏感性，以及这些加速度分量对反应的相对贡献。我们使用了两个人体头部独立建立并验证的有限元模型来评估结果中的模型一致性和依赖性：达特茅斯头部损伤模型和模拟损伤监测器。对于大脑的大部分区域，模拟中累积的体积加权区域峰值应变、应变率和冯·米塞斯应力与[公式：见正文]大小和持续时间的乘积（实际上就是旋转速度）显著相关，但与[公式：见正文]无关。仅由[公式：见正文]引起的反应与全自由度对应的反应相当，尤其是当通过致伤阈值进行归一化时（例如，在平均1 - 4%的典型差异百分比水平下，大差异的体积分数实际上减小（即[公式：见正文]1%））。这些模型一致的结果支持将旋转加速度的大小和持续时间纳入基于运动学的损伤指标，并证明了从单独的[公式：见正文]估计应变相关反应以分析与接触性运动相关的应变诱导损伤的可行性，且不会显著损失准确性，尤其是对于大脑。
