Impact parameters used to design the American football helmet and the parameters associated with mechanisms of concussive injury are not consistent. Head impacts resulting in concussive injury in football are characterized as events creating rotational motion of the head that generate brain tissue strain. The extent of tissue strain influences the resulting severity of injury. Helmet technology aimed to decrease brain tissue strain by reducing the extent of brain motion could help reduce injury risk. Current helmet performance and evaluation measures, such as peak resultant of linear and rotational acceleration, do not fully define directional brain motion and therefore cannot provide sufficient information for this type of improvement. This study was conducted to determine whether coordinate components (X, Y, and Z) of linear and rotational acceleration would correlate with maximum principal strain, a common measure of brain injury risk. Coordinate components define directional motion of the head and offer a specific design parameter more easily reduced using engineered structures than peak resultant acceleration. In addition to coordinate components, this study introduces the dominant component, defined as the coordinate component with the highest contribution to the resultant acceleration, for additional evaluation. The results show that the relationship between the X, Y, and Z coordinate components of acceleration and maximum principal strain is location- and direction-dependent. The study indicates a strong relationship between the peak resultant and dominant components of acceleration to maximum principal strain. Because the dominant component of acceleration accounts for direction and location, identifying the relationship between dominant acceleration and maximum principal strain demonstrates the potential use of this metric to improve future helmet innovation aimed at reducing tissue strain.

中文翻译：

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美式橄榄球头盔冲击的动态响应方向分量与最大主应变之间的关系

用于设计美式橄榄球头盔的冲击参数与与震荡损伤机制相关的参数不一致。在足球比赛中导致脑震荡的头部撞击被表征为产生头部旋转运动的事件，从而产生脑组织应变。组织应变的程度会影响由此产生的损伤严重程度。头盔技术旨在通过减少大脑运动的程度来减少脑组织应变，这有助于降低受伤风险。当前的头盔性能和评估措施，例如线性和旋转加速度的峰值结果，不能完全定义定向大脑运动，因此无法为此类改进提供足够的信息。本研究旨在确定坐标分量 (X, Y, 和 Z) 的线性和旋转加速度将与最大主应变相关，这是脑损伤风险的常用度量。坐标组件定义了头部的定向运动，并提供了一个特定的设计参数，使用工程结构比峰值合成加速度更容易减少。除了坐标分量外，本研究还引入了主导分量，定义为对合成加速度贡献最大的坐标分量，以进行额外评估。结果表明，加速度的 X、Y 和 Z 坐标分量与最大主应变之间的关系与位置和方向有关。该研究表明加速度的峰值合成分量和主要分量与最大主应变之间存在很强的关系。