Name: modified drop tower impact tests for american football helmets
Uploaded: 2017-02-19T13:00:00.000+00:00
Duration: 7 min 8 s
Description: Watch this Scientific Journal Video about Modified Drop Tower Impact Tests for American Football Helmets at JoVE.com

The authors would like to acknowledge the Center for Advanced Vehicular Systems (CAVS) at Mississippi State University for providing testing facilities and Rush Sports Medical of Meridian, Mississippi for their monetary support.

注:所提出的测试方法的协议是指下列NOCSAE文件（可在http://nocsae.org/）:NOCSAE DOC.002-13m13:"标准性能规格新生产的橄榄球头盔"18。 NOCSAE DOC.011-13m14d:"制造商程序指引本公司产品样本选择进行测试，以NOCSAE标准"24。 NOCSAE DOC.087-12m14:"对于足球FACEGUARDS冲击试验性能要求标准方法"25。 NOCSAE DOC.100-96m14:"故障排除指南测试设备和冲击试验"26。 NOCSAE DOC.101-00m14a:"设备的校准规程"27 1.测试装置<ol><li>构建NOCSAE双线下降支架组件作为NOCSAE DOC的第15.1节定义。 001，18， 如图5所示。确认大会所有组件都安装牢固。 </li><li>对准与头型旋转调节所需位置的头型领口和拧紧头型螺纹锁环安装尺寸"大"NOCSAE头型到放置支架组件。 注意:如果头模是新的或修理，参阅NOCSAE DOC的第5节。 100. 26 </li><li>牢固的三轴加速度计附接到位于所述头模的重心的加速度板。放置加速度在加速度计盘排队在与加速度计板中的孔的加速度两个孔的中心。使用内六角螺丝刀插入两个螺丝，直至该加速计牢固地安装在加速度计板以顺时针方向拧紧。 </li><li> 根据制造商的规范配置数据采集系统。 28 <ol><li> CONNEC吨的数据采集组件的电缆。 <ol><li>加速度计电缆连接到三路同轴分离器，那么同轴电缆连接到同轴分离器的每一个输出。 </li><li>每个同轴电缆的自由端从三通同轴分离器到通道1，2的传感器输入端口，和3位于放大器模块的后部连接。 </li><li>从放大器模块（信道1，2和3）上的数据采集系统（信道1，2和3，分别地）的前输入连接的输出端口连接的同轴线缆。 </li><li>在RS-232电缆的分裂端连接到数据采集系统的后部连接器。 </li><li>剩下的RS-232电缆连接到个人计算机（PC）的COM端口1。 </li></ol></li><li>电源的个人电脑（PC）和登录上。 </li><li>下载并安装数据采集系统软件到计算机上。 </li><li>上电数据采集组件:插上每个组件120伏电源插座插入电源，然后翻转放大器拨动开关至"ON"位置。 </li><li>双击位于桌面打开的软件的数据采集程序图标。 </li><li>观察一个提示，询问检查模块状态，请单击"是"。 </li><li>加载测试设置文件。点击"设置"选项卡上，向下滚动到"打开"，然后选择"测试设置"。 <ol><li>浏览电脑目录下，找到并选择标有"NOCSAE1.TSF"测试设置文件。点击"加载"。 </li></ol></li><li>输入该加速度传感器的信息。 <ol><li>单击活动模块通道3黄色传感器输入图标。 </li><li>插入的z轴加速度校准值（毫伏/ G）进入"CAL值"文本框。 </li><li>点击"上一个"按钮。 </li><li>重复步骤1.4.8.1 - 1.4.8.3对于y轴加速度（信道2）和用于第E X轴加速度计（信道1）。 </li><li>点击绿色的"返回"按钮，退出传感器。 </li></ol></li><li>点击绿色的"保存"图标，然后命名测试设置为"NOCSAE-朱庇特"。 </li><li>点击"保存"。 </li></ol></li></ol> 2.准备头盔<ol><li>选择冲击试验头盔模型。用于头盔的认证，用于根据NOCSAE DOC.011测试选择的样品。 24试验按表1和图1和2中所示的样品。 </li><li>选择每个选定的头盔模型对应的faceguards。从NOCSAE标准不同，与基线面甲这样的头盔进行基础安全帽冲击试验。 </li><li>使用飞利浦螺丝刀，牢固地安装正确的面甲，所有面甲特定的硬件来选择测试每个头盔。与此相反的NOCSAE标准测试方法具D，测试附加faceguards所有的头盔。 </li><li> 根据表1，NOCSAE DOC在温度条件头盔。 002 7，以及NOCSAE DOC.087 25 通过暴露于实验室环境或环境室中。在室温下进行初步头盔跌落测试。 <ol><li>测试之前将所选头盔到实验室环境中，72°F±5°F（22℃，±2℃）中，在至少4个小时。 </li><li>如果所有的环境温度的影响已经进行，暴露的头盔的调节温度，根据表1，对于4但不超过24小时的长。 7 注:至少有两个，但没有导致最高记录SI四个以上的撞击位置环境温度下降会在高温下进行测试值。 </li></ol></li></ol> 3.校准<ol><li> 执行校准头型:每头型必须使用三轴加速度计测试之前进行校准，3"校准MEP垫和放置位置/为该特定的校准MEP垫确定的年度NOCSAE校准垫鉴定报告的速度。 <ol><li>牢固地连接3"校准MEP垫用内六角扳手砧。 </li><li>使用年度NOCSAE校准垫鉴定报告，选择一个撞击位置和相应的冲击速度。 </li><li>使用头模旋转器组件和砧座导轨，调整头模和砧座到所需冲击方向（正面，侧面，或者顶部）。参考表1，NOCSAE DOC的附录2。 001，18日和NOCSAE DOC。 100. 26 <ol><li>移除头模旋转体组件上的锥形-LOC螺栓和定向头模调节到对准螺栓孔到所需的位置。插入和安全地发斯登锥度-LOC螺栓。 </li><li>松开头型螺纹锁环和旋转头型鼻翼位置到所需方向。拧紧头型螺纹锁环。 </li><li>松开两个底板砧螺栓，直到达到预期的效果的位置，实现滑动砧。拧紧基地板状砧螺栓并确保所有连接是否紧固。 </li></ol></li><li>附加发布系统下降支架组件。解除降托架组件到释放系统的高度。居中释放系统的下拉滑座组件的连接点然后为电磁释放系统的切换开关拨至"ON"位置。 </li><li>提高车厢掉落装配决心达到预期的冲击速度的具体高度。注意:特定高度可以为每个系统由于摩擦而变化。更多的影响，可能需要进行变化的高度，以确保正确的入速度是一个chieved。 </li><li>准备用于记录的事件数据采集系统（根据制造商的规格28）。 <ol><li>加载测试设置文件。点击"测试"选项卡，然后单击"收集数据"。 </li><li>浏览电脑目录下，找到并选择标有"NOCSAE-JoVE.TSF"测试设置文件。点击"加载"。 </li><li>点击"确定"。 </li><li>键入测试说明"说明"对话框，然后按"Tab"键。 </li><li>提供了5个字符的测试ID，输入"JoVE1"，然后点击"继续"。 </li><li>点击"继续"。 </li><li>观察仪表升温。一旦计数器达到15秒，单击"继续"。 </li><li>观察自动执行加速度校准该系统。一旦所有的箱子为绿色，单击"继续"。 </li></ol></li><li>使用发布制度，跌落马车assembly和触发数据采集系统通过同时翻转位于释放系统电源控制箱既拨动开关来记录事件。 </li><li>计算并记录所得的SI值。确保结果是1200 SI±2％。 </li><li>重复步骤3.4.2-3.4.8直到结果为三个所需撞击位置而获得的。 注:校准垫应每年在由NOCSAE指定的实验室进行重新确认。 </li></ol></li><li>执行系统检查和维护的结果。 （见18，NOCSAE DOC.001 18） </li></ol> 4.测试过程<ol><li>执行系统检查和维护的结果。 </li><li>交换用于校准的MEP测试焊盘的MEP垫。 </li><li>选择冲击位置和根据表1的测试速度。 注意:影响必须从最低降速度至最高进行。环境温度影响，建议立即进行删除D是以前条件的影响进行。 </li><li>适当调整头模方向和砧座的位置，以达到预期的冲击的位置，如在图1和2，并根据在第3步骤中描绘。 </li><li>选择测试头盔。 </li><li>根据头盔制造商安装说明和NOCSAE程序选择正确头盔适合头型。调整和牢固地安装在头盔南极的头型。 注意:由于该面甲的附加约束，滑石粉的光应用可以在头盔的头模的嵌合帮助。 </li><li>附加的机械释放系统下降支架组件。 </li><li>提高车厢掉落装配决心达到预期的冲击速度的具体高度。 </li><li>准备的数据采集系统，用于记录一个事件。重复步骤3.4.1至3.4.8。 </li><li>使用机械释放系统跌落CARRI年龄组件和同时触发数据采集系统以记录该事件。 </li><li>撞击后，立即记录SI，HIC和峰值加速度的结果。 </li><li>比较记录的结果通过/失败的标准。从NOCSAE标准不同，设置了一通/所有5.46，4.88失败700 SI的价值，4.23米/秒的影响。保持合格/不合格300 SI的标准对所有3.46米/秒的影响。 </li><li>重复步骤4.3-4.11，直到结果为所有需要的影响获得的。 注:这是可以接受的改变头型的方向和位置，砧之前测试一个给定的冲击位置所有的头盔。 </li><li>执行测试完成后系统检查和维护的效果。 </li><li>数据验证:比较检测前和后测系统的检查和确保任何变化是7％或更少。 </li></ol><img alt="图1" src="/files/ftp_upload/53929/53929table1.jpg" /> 表格1:橄榄球头盔跌落试验矩阵表示由滴落速度（米/秒）和冲击位置所需的影响。 （表从NOCSAE DOC修改。002-13m13） <a href="https://jove.unicartagenaproxy.elogim.com/files/ftp_upload/53929/53929table1large.jpg" target="_blank">点击此处查看该图的放大版本。</a>

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The authors have nothing to disclose.

报告的方法，夫妻NOCSAE橄榄球头盔面甲并跌落冲击试验提供了一个独特的技术来评估现代足球头盔更好的性能。评价现代足球头盔这更好的性能特点，最关键的步骤如下:1）正确设置机械试验装置; 2）准确地进行校准程序; 3）正确连接头盔/面甲的头型。 这种方法需要适当的测试设置和校准程序。有由于制造过程中的限制，其中包括在聚合材料的孔隙率每NOCSAE头模之间固有可?...

动机 这个修改后的落塔试验方法的主要目标是要更紧密地代表美国橄榄球头盔系统对场的影响，促进提高安全标准。该entailed试验方法可以提供头盔，有效地开发脑震荡预防头饰增强系统需要应对的知识。脑震荡的发生一贯困扰接触的运动，比如美式足球。仅在美国，与体育有关的脑震荡被估计将要发生，每年1.6至3.8万次。 1橄榄球运动员可以有超过1500个每个赛季头的影响。 2，3虽然大多数影响的程度可能是次震荡，这些影响是由于被称为慢性创伤性脑病（CTE）的冲击引起的神经变性疾病的积累可能导致长期的脑损伤。 4CTE被链接到tau蛋白在大脑中积聚，导致记忆丧失，行为和人格改变，帕金森氏综合征，和语音和步态异常已有时会导致自杀。 5橄榄球头盔已经在过去15年中取得了一定的技术进步，但即使是当今最先进的头盔并不能完全缓解所有的事件力量在头盔上，因此，运动员仍然招致脑震荡。通过BARTSCH 等人进行的一项研究。 6表明，在许多情况下，头部撞击剂量和在穿着老式Leatherhead的头盔是可比的那些穿着广泛使用的21 世纪的头盔，示出了用于在设计和测试标准橄榄球头盔的改进的需要头部受伤的风险。特别是，NOCSAE认证7不需要面甲要包括在该头盔的跌落试验。从t附加的刚度他面甲连接到头盔将极大地改变整个机械响应。本研究需要一种方法，以提供更强大的头盔安全标准，将作为驱动力来促进安全头盔设计。 背景 颅脑损伤指标 有关脑震荡的确切生物学机制仍然不明。虽然很多工作已经在试图通过各种损伤指标来量化颅脑损伤容限已经完成，意见分歧已经出现在关于这些标准的生物医学界。这些损伤的机制都应该涉及到一些实体:直线加速，旋转加速度，冲击持续时间和冲动。 8，9，10，11的几个损伤标准已经用于定义一个震荡线性加速度的量度。韦恩州立公差曲线（WSTC） <suP类="外部参照"&gt; 12，13，14被开发通过定义线性加速度随冲击持续时间的阈值的曲线边界正面碰撞时，预测为汽车撞车颅骨骨折。 WSTC曾担任其他伤害的标准，例如严重程度指数（SI）11基地 而头部伤害指数（HIC），15这是两种最常用的标准。的SI和HIC基于所述线性加速度 - 时间曲线加权积分两个量度影响严重性。而这些标准定义了线性加速度的阈值，其他的标准，已经提出以考虑转动加速度，如头部冲击功率索引。 8，10，16今天的头盔测试标准通常使用基于韦恩州立要伤害标准lerance曲线（即HIC或SI）或峰值加速度标准或在某些情况下，这两个。虽然需要一些修改角加速度添加到标准的性能标准，基于线性加速度标准仍然占主导地位。 在这项研究中，使用的指标来评估的相对安全性，所提供的每个头盔是峰值所得加速度，SI和HIC值。这些指标中，只有SI是用于当前全国工作委员会标准田径设备（NOCSAE）橄榄球头盔的标准评价。在SI是基于以下等式， <img alt="式（1）" src="/files/ftp_upload/53929/53929eq1.jpg" width="100" /> （1） 其中A是重力的头部的中心（CG）的平移加速度，和t是加速度的持续时间。 11，17 SI计算根据:õNOCSAE标准18，其中，计算由沿所得加速度曲线的4G阈限定。的HIC值通过下列公式计算， <img alt="式（1）" src="/files/ftp_upload/53929/53929eq2.jpg" width="325" /> （2） 其中a是头部的重心的平移加速度，和叔 1和t 2是最初和最后的时间，分别在其HIC达到最大值的时间间隔的。所有的HIC值在这项研究中分别为HIC 36，其中该时间间隔的持续时间被限制为36毫秒计算的。 NOCSAE橄榄球头盔测试标准 NOCSAE概述 1969年NOCSAE成立，以开发用于美式橄榄球头盔/ faceguards等运动设备，减少运动伤害的目标性能标准。 17 NOCSAE橄榄球头盔标准由韦恩州立大学的沃伊特霍奇森博士9人开发的建立影响衰减和结构的完整性要求橄榄球头盔/ faceguards，以减少头部受伤。这些橄榄球头盔标准包括认证测试和头盔年度换发新证手续。到2015年，实现NOCSAE需要使用特定的美国国家标准协会（ANSI）认可的机构头盔认证的质量保证计划。 NOCSAE测试方法 该NOCSAE橄榄球头盔标准不包括与faceguards头盔的测试，因为它正在开展头盔滴之前要求其删除。所述NOCSAE头盔测试标准17利用依赖于重力，以加速头模和头盔组合到所需冲击速度双线滴撞击。该NOCSAE头模的仪表W¯¯在重心i个三轴加速度计。头型和头盔的组合，然后在特定的速度下降到覆盖着厚12.7mm的硬质橡胶弹性体的模块化编程（MEP）垫钢砧。在冲击，瞬时加速度被记录和计算的SI值。这些SI值是针对一通比较/失败的标准在各种需要的撞击位置和速度以及两个温度，包括环境和高温的影响。如果任何影响所产生的SI值超出阈值，则该头盔将无法通过测试。 一个单独的标准测试方法用于足球甲头盔认证。所述NOCSAE足球面甲标准包括结构完整性分析以及评估所述面甲，南极的冲击衰减性能，和它们的附连系统。每一次撞击测试必须低于1200 SI通过测试，没有正面接触，也没有我任何部件的机械故障，如由NOCSAE标准定义的。 19 有一个提议增加NOCSAE测试（线性冲击器（LI））20，其中包括与面甲头盔，而是因为它不能承认冠的影响是不恰当的橄榄球头盔认证。对LI使用一个气动推杆撞击位于配备以诱导角加速度安装在一个线性轴承表的混合动力车第三虚设颈部NOCSAE头模头盔。由于这个原因，李试验是额外的试验，以目前的双网NOCSAE跌落试验过程而不是替代。 20，21相反的李测试中，我们提出简单地两个场景添加到当前双网跌落试验过程。 足球头盔认证NOCSAE标准测试方法目前包括六个规定的影响LOCAtions和单随机冲击的位置。该规定的撞击位置包括以下内容:前（F），前老板（FB），侧面（S），后（R），后老板（RB）和上衣（T）。随机冲击位置试验可以从头盔的规定的可接受影响区域内的任何点选择一个区域。我们修改NOCSAE落塔试验的撞击位置包括什么被命名为前上（FT）和前大老板（FTB）撞击位置替换先前定义的接待和前老板撞击位置。我们前面顶板和前大老板撞击位置相同，为长曲棍球头盔的NOCSAE标准和右前老板撞击位置，其中也包括跌落试验的面甲。 22头盔壳冲击地点，包括被替换的正面和前老板位置，在图1中描绘。 此外，我们目前的研究修改安全帽测试方法包括两个面甲IMPAC这被命名为FG接待和FG底部T形的位置。两个面甲的影响的位置是相同的，为当前NOCSAE面甲认证程序所需的冲击的位置。用于本研究的改性NOCSAE冲击测试八个撞击位置示于图2。 <img alt="图1" src="/files/ftp_upload/53929/53929fig1.jpg" /> 图1:橄榄球头盔近似撞击位置。这六个当前所需要NOCSAE跌落试验头盔撞击位置，前（F），前老板（FB），侧面（S），上衣（T），后（R）和后部凸台（RB），和两个建议撞击位置，前顶（FT）和前大老板（FTB）。注:安全帽的NOCSAE标准测试方法不包括前顶板和前大老板撞击位置（以红色文字显示），本研究中，他们更换前和前老板撞击位置。 （图片来自NOCSAE DOC修改。001-13m15b） <aHREF ="https://jove.unicartagenaproxy.elogim.com/files/ftp_upload/53929/53929fig1large.jpg"目标="_空白"&gt;点击此处查看该图的放大版本。 <img alt="图2" src="/files/ftp_upload/53929/53929fig2.jpg" /> 图2: 修改NOCSAE跌落测试设置显示8次位置。前顶，前顶boss，边，面甲（FG）正投，背投，背投老大，顶部和底部面甲（FB）。注:NOCSAE标准不包括面甲附件，这里接待顶板和前大老板取代标准的接待和前老板撞击位置。 （图片来自NOCSAE DOC修改。002-11m12） <a href="https://jove.unicartagenaproxy.elogim.com/files/ftp_upload/53929/53929fig2large.jpg" target="_blank">点击此处查看该图的放大版本。</a> 头盔设计在过去十年中已逐步改变，而NOCSAE足球头盔标准从未附带小时面甲ELMET在评价足球头盔性能规格。虽然，最近一项修正案已取得包括合格/不合格的最低速度的影响（3.46米/秒），一般通过/失败1200 SI的上限300 SI的价值自1997年17 1997年之前并没有改变，该NOCSAE使用1500 SI PASS / FAIL标准。 Hodgson 等人。 （1970年）显示，大于1000的SI值是对生命的危险，而540 SI值非头盔尸体碰撞试验已经产生线性颅骨骨折。 23最现代化的橄榄球头盔表明通过远低于1200 SI限制，但不是全部低于540 SI。

<table><tbody><tr><td>PCB Triaxial Accelerometers</td><td>PCB</td><td>Model 353B17</td><td></td></tr><tr><td>TDAS2 Data Acqusition System</td><td>Diversified Technical Systems, Inc.&amp;nbsp;</td><td>TDAS2</td><td>Or an equivalent Data Acquisition System</td></tr><tr><td>Current Source (Amplifier)&amp;nbsp;</td><td>Dytran Instruments, Inc.</td><td>4114B1</td><td>Or equivalent</td></tr><tr><td>Velocity gate and flag</td><td>CADEX</td><td>SB203</td><td>Or an equivalent velocimeter</td></tr><tr><td>Selected Football Helmet(s)/faceguard assem.</td><td></td><td>including chinstrap and faceguard hardware</td><td></td></tr><tr><td>Height Gauge</td><td></td><td></td><td></td></tr><tr><td>Torque wrench</td><td>Snap-on</td><td>QD21000</td><td>range to 200 in/lb minimum, 5% accuracy</td></tr><tr><td>&lt;strong&gt;Twin-wire Guide Assembly&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Drop Carriage&amp;nbsp;</td><td>SIRC</td><td>1001</td><td></td></tr><tr><td>1/2&quot; MEP Testing Pad</td><td>SIRC</td><td>1006</td><td></td></tr><tr><td>1/8&quot; Faceguard Testing Pad</td><td>SIRC</td><td>1007</td><td></td></tr><tr><td>3&quot; MEP Calibration Pad</td><td>SIRC</td><td>1005</td><td>Including Annual NOCSAE Calibration Pad Qualification Report</td></tr><tr><td>3/8&quot; Hook-eye Turnbuckle</td><td>SIRC</td><td>1043</td><td>Forged Steel with a 6&quot; take-up</td></tr><tr><td>1/8&quot; Wire Rope Thimble&amp;nbsp;</td><td>SIRC</td><td>1044</td><td></td></tr><tr><td>1/8&quot; Spring Music Wire&amp;nbsp;</td><td>SIRC</td><td>1045</td><td></td></tr><tr><td>1/8&quot; Wire Rope, Tiller Rope Clamp, Bronze&amp;nbsp;</td><td>SIRC</td><td>1046</td><td></td></tr><tr><td>3/8&quot; 16 x 3&amp;ldquo; Eye Bolt&amp;nbsp;</td><td>SIRC</td><td>1041</td><td></td></tr><tr><td>3/8&quot; Forged Eye Bolt</td><td>SIRC</td><td>1040</td><td></td></tr><tr><td>Right Angle DC Hoist Motor&amp;nbsp;</td><td>SIRC</td><td>2000</td><td></td></tr><tr><td>Single Groove Sheave (Pulley), 3 &amp;frac34;&quot;&amp;nbsp;</td><td>SIRC</td><td>2002</td><td></td></tr><tr><td>Top Mount Plate</td><td>SIRC</td><td>2003</td><td></td></tr><tr><td>18&quot; Top Channel Bracket&amp;nbsp;</td><td>SIRC</td><td>2004</td><td></td></tr><tr><td>Wall Mount Channel Bracket, 4&#039; x 1 5/8&quot;&amp;nbsp;</td><td>SIRC</td><td>2005</td><td></td></tr><tr><td>Mechanical Release System&amp;nbsp;</td><td>SIRC</td><td>2006</td><td></td></tr><tr><td>Lift Cable, Wire Rope, 20&#039; Coil&amp;nbsp;</td><td>SIRC</td><td>2007</td><td></td></tr><tr><td>Anvil Base Plate&amp;nbsp;</td><td>SIRC</td><td>2010</td><td></td></tr><tr><td>Anvil&amp;nbsp;</td><td>SIRC</td><td>2011</td><td></td></tr><tr><td>Headform Adjuster&amp;nbsp;</td><td>SIRC</td><td>2012</td><td></td></tr><tr><td>Headform Rotator Stem</td><td>SIRC</td><td>2013</td><td></td></tr><tr><td>Headform Threaded Lock ring</td><td>SIRC</td><td>2016</td><td></td></tr><tr><td>&amp;nbsp;Headform Collar&amp;nbsp;</td><td>SIRC</td><td>2014</td><td></td></tr><tr><td>Nylon Bushing&amp;nbsp;</td><td>SIRC</td><td>1803</td><td></td></tr><tr><td>Small Headform&amp;nbsp;</td><td>SIRC</td><td>1100</td><td></td></tr><tr><td>Medium Headform&amp;nbsp;</td><td>SIRC</td><td>1101</td><td></td></tr><tr><td>Large Headform</td><td>SIRC</td><td>1102</td><td></td></tr><tr><td>Taper-Loc Bolt</td><td></td><td></td><td></td></tr><tr><td>DC Motor Speed Controller (Reversible)&amp;nbsp;</td><td>SIRC</td><td>2001</td><td></td></tr></tbody></table>

modified drop tower impact tests for american football helmets

A modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test method for American football helmet drop impact test standards is presented that would provide better assessment of a helmet's on-field impact performance by including a faceguard on the helmet. In this study, a merger of faceguard and helmet test standards is proposed. The need for a more robust systematic approach to football helmet testing procedures is emphasized by comparing representative results of the Head Injury Criterion (HIC), Severity Index (SI), and peak acceleration values for different helmets at different helmet locations under modified NOCSAE standard drop tower tests. Essentially, these comparative drop test results revealed that the faceguard adds a stiffening kinematic constraint to the shell that lessens total energy absorption. The current NOCSAE standard test methods can be improved to represent on-field helmet hits by attaching the faceguards to helmets and by including two new helmet impact locations (Front Top and Front Top Boss). The reported football helmet test method gives a more accurate representation of a helmet's performance and its ability to mitigate on-field impacts while promoting safer football helmets.

结果此方法的详细定量分析拉什等人提出。 （提交）的结果的概要和一个耦合面甲-壳头盔测试方法的相关联的有效性被显示在使用罗林斯量子另外，里德尔360，舒特离子4D和Xenith X2头盔作为例子跌落试验结果。这些头盔与faceguards显示不同的结果（大小的"大"）的每个相比没有faceguards头盔。 图3比较绘制每个例子头盔的SI值有和没有5.46米/秒的冲?...

Watch this Scientific Journal Video about Modified Drop Tower Impact Tests for American Football Helmets at JoVE.com

Modified Drop Tower Impact Tests for American Football Helmets

This article provides a novel technique to assess the performance characteristics of American football helmets by inclusion of faceguards during NOCSAE Standard drop tests. Additionally, two more impact locations are proposed to be added to the NOCSAE certification.

修改落塔冲击试验为美国橄榄球头盔

A modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test method for American football helmet drop impact test standards ...

modified-drop-tower-impact-tests-for-american-football-helmets

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SCIENTISTS IN ACTION

10.8K 次观看.  Mississippi State University. This article provides a novel technique to assess the performance characteristics of American football helmets by inclusion of faceguards during NOCSAE Standard drop tests. Additionally, two more impact locations are proposed to be added to the NOCSAE certification. 

视频: Modified Drop Tower Impact Tests for American Football Helmets

An Investigation of the Effects of Sports-related Concussion in Youth Using Functional Magnetic Resonance Imaging and the Head Impact Telemetry System

One of the most commonly reported injuries in children who participate in sports is concussion or mild traumatic brain injury (mTBI)1. Children and youth involved in organized sports such as competitive hockey are nearly six times more likely to suffer a severe concussion compared to children involved in other leisure physical activities2. While the most common cognitive sequelae of mTBI appear similar for children and adults, the recovery profile and breadth of consequences in children remains largely unknown2, as does the influence of pre-injury characteristics (e.g. gender) and injury details (e.g. magnitude and direction of impact) on long-term outcomes. Competitive sports, such as hockey, allow the rare opportunity to utilize a pre-post design to obtain pre-injury data before concussion occurs on youth characteristics and functioning and to relate this to outcome following injury. Our primary goals are to refine pediatric concussion diagnosis and management based on research evidence that is specific to children and youth. To do this we use new, multi-modal and integrative approaches that will:
 1.Evaluate the immediate effects of head trauma in youth 
2.Monitor the resolution of post-concussion symptoms (PCS) and cognitive performance during recovery 
3.Utilize new methods to verify brain injury and recovery
To achieve our goals, we have implemented the Head Impact Telemetry (HIT) System. (Simbex; Lebanon, NH, USA). This system equips commercially available Easton S9 hockey helmets (Easton-Bell Sports; Van Nuys, CA, USA) with single-axis accelerometers designed to measure real-time head accelerations during contact sport participation 3 - 5. By using telemetric technology, the magnitude of acceleration and location of all head impacts during sport participation can be objectively detected and recorded. We also use functional magnetic resonance imaging (fMRI) to localize and assess changes in neural activity specifically in the medial temporal and frontal lobes during the performance of cognitive tasks, since those are the cerebral regions most sensitive to concussive head injury 6. Finally, we are acquiring structural imaging data sensitive to damage in brain white matter.

This article provides an overview of a multi-modal approach to mild traumatic brain injury diagnosis and recovery in youth. This approach combines neuropsychological testing with functional magnetic resonance imaging and the Head Impact Telemetry System to monitor the relationship between head impacts and brain activity during cognitive testing.

在使用功能性磁共振成像和头部撞击遥测系统的青年与体育有关的震荡影响的调查

One of the most commonly reported injuries in children who participate in sports is concussion or mild traumatic brain injury (mTBI)1. Children and youth ...

科研

医学

Laboratory Drop Towers for the Experimental Simulation of Dust-aggregate Collisions in the Early Solar System

For the purpose of investigating the evolution of dust aggregates in the early Solar System, we developed two vacuum drop towers in which fragile dust aggregates with sizes up to ~10 cm and porosities up to 70% can be collided. One of the drop towers is primarily used for very low impact speeds down to below 0.01 m/sec and makes use of a double release mechanism. Collisions are recorded in stereo-view by two high-speed cameras, which fall along the glass vacuum tube in the center-of-mass frame of the two dust aggregates. The other free-fall tower makes use of an electromagnetic accelerator that is capable of gently accelerating dust aggregates to up to 5 m/sec. In combination with the release of another dust aggregate to free fall, collision speeds up to ~10 m/sec can be achieved. Here, two fixed high-speed cameras record the collision events. In both drop towers, the dust aggregates are in free fall during the collision so that they are weightless and match the conditions in the early Solar System.

We present a technique to achieve low-velocity to intermediate-velocity collisions between fragile dust aggregates in the laboratory. For this purpose, two vacuum drop-tower setups have been developed that allow collision velocities between &#60;0.01 and ~10 m/sec. The collision events are recorded by high-speed imaging.

实验室落塔的粉尘聚集在碰撞早期太阳系的实验模拟

For the purpose of investigating the evolution of dust aggregates in the early Solar System, we developed two vacuum drop towers in which fragile dust ...

工程学

Vision Training Methods for Sports Concussion Mitigation and Management

There is emerging evidence supporting the use vision training, including light board training tools, as a concussion baseline and neuro-diagnostic tool and potentially as a supportive component to concussion prevention strategies. This paper is focused on providing detailed methods for select vision training tools and reporting normative data for comparison when vision training is a part of a sports management program. The overall program includes standard vision training methods including tachistoscope, Brock&#8217;s string, and strobe glasses, as well as specialized light board training algorithms. Stereopsis is measured as a means to monitor vision training affects. In addition, quantitative results for vision training methods as well as baseline and post-testing *A and Reaction Test measures with progressive scores are reported. Collegiate athletes consistently improve after six weeks of training in their stereopsis, *A and Reaction Test scores. When vision training is initiated as a team wide exercise, the incidence of concussion decreases in players who participate in training compared to players who do not receive the vision training. Vision training produces functional and performance changes that, when monitored, can be used to assess the success of the vision training and can be initiated as part of a sports medical intervention for concussion prevention.

This paper describes a protocol to conduct, quantitatively monitor, and assess the success of vision training initiated as part of a sports medical management program including intervention for concussion prevention and performance enhancement.

视觉训练方法体育震荡缓解与管理

There is emerging evidence supporting the use vision training, including light board training tools, as a concussion baseline and neuro-diagnostic tool ...

行为学

A Contusive Model of Unilateral Cervical Spinal Cord Injury Using the Infinite Horizon Impactor

While the majority of human spinal cord injuries occur in the cervical spinal cord, the vast majority of laboratory research employs animal models of spinal cord injury (SCI) in which the thoracic spinal cord is injured. Additionally, because most human cord injuries occur as the result of blunt, non-penetrating trauma (e.g. motor vehicle accident, sporting injury) where the spinal cord is violently struck by displaced bone or soft tissues, the majority of SCI researchers are of the opinion that the most clinically relevant injury models are those in which the spinal cord is rapidly contused.1 Therefore, an important step in the preclinical evaluation of novel treatments on their way to human translation is an assessment of their efficacy in a model of contusion SCI within the cervical spinal cord. Here, we describe the technical aspects and resultant anatomical and behavioral outcomes of an unilateral contusive model of cervical SCI that employs the Infinite Horizon spinal cord injury impactor.
Sprague Dawley rats underwent a left-sided unilateral laminectomy at C5. To optimize the reproducibility of the biomechanical, functional, and histological outcomes of the injury model, we contused the spinal cords using an impact force of 150 kdyn, an impact trajectory of 22.5&deg; (animals rotated at 22.5&deg;), and an impact location off of midline of 1.4 mm. Functional recovery was assessed using the cylinder rearing test, horizontal ladder test, grooming test and modified Montoya's staircase test for up to 6 weeks, after which the spinal cords were evaluated histologically for white and grey matter sparing.
The injury model presented here imparts consistent and reproducible biomechanical forces to the spinal cord, an important feature of any experimental SCI model. This results in discrete histological damage to the lateral half of the spinal cord which is largely contained to the ipsilateral side of injury. The injury is well tolerated by the animals, but does result in functional deficits of the forelimb that are significant and sustained in the weeks following injury. The cervical unilateral injury model presented here may be a resource to researchers who wish to evaluate potentially promising therapies prior to human translation.

A reliable and repeatable way to produce a cervical unilateral spinal cord injury using the Infinite Horizon impactor is described. The method takes advantage of a custom designed frame and clamp to stabilize the spine. The standardized procedure and biomechanical injury parameters result in sufficient and sustained injuries.

单侧颈脊髓损伤的挫伤模型，利用无限的地平线冲击

While the majority of human spinal cord injuries occur in the cervical spinal cord, the vast majority of laboratory research employs animal models of ...

Data Acquisition Protocol for Determining Embedded Sensitivity Functions

The effectiveness of many structural health monitoring techniques depends on the placement of sensors and the location of input forces. Algorithms for determining optimal sensor and forcing locations typically require data, either simulated or measured, from the damaged structure. Embedded sensitivity functions provide an approach for determining the best available sensor location to detect damage with only data from the healthy structure. In this video and manuscript, the data acquisition procedure and best practices for determining the embedded sensitivity functions of a structure is presented. The frequency response functions used in the calculation of the embedded sensitivity functions are acquired using modal impact testing. Data is acquired and representative results are shown for a residential scale wind turbine blade. Strategies for evaluating the quality of the data being acquired are provided during the demonstration of the data acquisition process.

The data acquisition procedure for determining embedded sensitivity functions is described. Data is acquired and representative results are shown for a residential scale wind turbine blade.

数据采集​​协议确定嵌入式灵敏度功能

The effectiveness of many structural health monitoring techniques depends on the placement of sensors and the location of input forces. Algorithms for ...

In Vivo Protocol of Controlled Subconcussive Head Impacts for the Validation of Field Study Data

Subconcussive hits pose a threat to neuronal health as they have shown to induce neuronal structural damage and functional impairment without causing outward symptomology and appear to be a key contributor to an irreversible neurodegenerative disease, chronic traumatic encephalopathy (CTE). In addition, athletes can incur more than 1,000 of these hits per season. The subconcussive soccer heading model (SSHM) is a relevant, reproducible, and leading method of isolating and examining the effects of these subconcussive head impacts. By controlling variables such as ball traveling speed, the frequency of impacts, interval, ball placement to the head, as well as by measuring head impact magnitude, the SSHM provides the scientific community with a superior avenue of investigating the acute subconcussive effects on neuronal health. In this paper, we demonstrate the utility of SSHM in studying a time-course expression of neurofilament-light polypeptide (NF-L) in plasma in a repeated measures fashion. NF-L is an axonal injury marker that has previously been shown to be elevated in boxers and football players following subconcussive head trauma. Thirty-four adult aged soccer players were recruited and randomly assigned to either a soccer heading (n = 18) or kicking (n = 16) group. The heading group executed 10 headers with soccer balls projected at a velocity of 25 mph over 10 min. The kicking group followed the same protocol with 10 kicks. Plasma samples were obtained before and at 0 h, 2 h, and 24 h after heading/kicking and assessed for NF-L expressions. The heading group showed a gradual increase in plasma NF-L expression and peaked at 24 h after the heading protocol, whereas the kicking group remained consistent across the time points. These results confirmed the NF-L data from clinical field studies, encouraging the use of SSHM to validate clinical subconcussion data.

The subconcussive soccer heading model is a safe and concise methodological approach to isolate and measure the effects of subconcussive head impacts.

控制下冲击头冲击的活体协议对现场研究数据的验证

Subconcussive hits pose a threat to neuronal health as they have shown to induce neuronal structural damage and functional impairment without causing ...

Cutting Procedures, Tensile Testing, and Ageing of Flexible Unidirectional Composite Laminates

Many body armor designs incorporate unidirectional (UD) laminates. UD laminates are constructed of thin (&#60;0.05 mm) layers of high-performance yarns, where the yarns in each layer are oriented parallel to each other and held in place using binder resins and thin polymer films. The armor is constructed by stacking the unidirectional layers in different orientations. To date, only very preliminary work has been performed to characterize the ageing of the binder resins used in unidirectional laminates and the effects on their performance. For example, during the development of the conditioning protocol used in the National Institute of Justice Standard-0101.06, UD laminates showed visual signs of delamination and reductions in V50, which is the velocity at which half of the projectiles are expected to perforate the armor, after ageing. A better understanding of the material property changes in UD laminates is necessary to comprehend the long-term performance of armors constructed from these materials. There are no current standards recommended for mechanically interrogating unidirectional (UD) laminate materials. This study explores methods and best practices for accurately testing the mechanical properties of these materials and proposes a new test methodology for these materials. Best practices for ageing these materials are also described.

The goal of the study was to develop protocols to prepare consistent specimens for accurate mechanical testing of high-strength aramid or ultra-high-molar-mass polyethylene-based flexible unidirectional composite laminate materials and to describe protocols for performing artificial ageing on these materials.

柔性单向复合层压板的切割程序、拉伸测试和老化

Many body armor designs incorporate unidirectional (UD) laminates. UD laminates are constructed of thin (&#60;0.05 mm) layers of high-performance yarns, ...

Method and Instrumented Fixture for Femoral Fracture Testing in a Sideways Fall-on-the-Hip Position

Mechanical testing of femora brings valuable insights into understanding the contribution of clinically-measureable variables such as bone mineral density distribution and geometry on the femoral mechanical properties. Currently, there is no standard protocol for mechanical testing of such geometrically complex bones to measure strength, and stiffness. To address this gap we have developed a protocol to test cadaveric femora to fracture and to measure their biomechanical parameters. This protocol describes a set of adaptable fixtures to accommodate the various load magnitudes and directions accounting for possible bone orientations in a fall on the hip configuration, test speed, bone size, and left leg-right leg variations. The femora were prepared for testing by cleaning, cutting, scanning, and potting the distal end and greater trochanter contact surfaces in poly(methyl methacrylate) (PMMA) as presented in a different protocol. The prepared specimens were placed in the testing fixture in a position mimicking a sideways fall on the hip and loaded to fracture. During testing, two load cells measured vertical forces applied to the femoral head and greater trochanter, a six-axis load cell measured forces and moments at the distal femoral shaft, and a displacement sensor measured differential displacement between the femoral head and trochanter contact supports. High speed video cameras were used to synchronously record the sequence of fracture events during testing. The reduction of this data allowed us to characterize the strength, stiffness, and fracture energy for nearly 200 osteoporotic, osteopenic, and normal cadaveric femora for further development of engineering-based diagnostic tools for osteoporosis research.

In this manuscript, we present a protocol to fracture test cadaveric proximal femora in a sideways fall on the hip configuration using instrumented fixtures mounted on a standard servo hydraulic frame. Nine digitized signals comprising forces, moments, and displacement along with two high speed video streams are acquired during testing.

方法和股骨骨折测试在横盘整理的秋天在臀部位置检测的夹具

Mechanical testing of femora brings valuable insights into understanding the contribution of clinically-measureable variables such as bone mineral density ...

生物工程

A Test Bed to Examine Helmet Fit and Retention and Biomechanical Measures of Head and Neck Injury in Simulated Impact

Conventional wisdom and the language in international helmet testing and certification standards suggest that appropriate helmet fit and retention during an impact are important factors in protecting the helmet wearer from impact-induced injury. This manuscript aims to investigate impact-induced injury mechanisms in different helmet fit scenarios through analysis of simulated helmeted impacts with an anthropometric test device (ATD), an array of headform acceleration transducers and neck force/moment transducers, a dual high speed camera system, and helmet-fit force sensors developed in our research group based on Bragg gratings in optical fiber. To simulate impacts, an instrumented headform and flexible neck fall along a linear guide rail onto an anvil. The test bed allows simulation of head impact at speeds up to 8.3 m/s, onto impact surfaces that are both flat and angled. The headform is fit with a crash helmet and several fit scenarios can be simulated by making context specific adjustments to the helmet position index and/or helmet size. To quantify helmet retention, the movement of the helmet on the head is quantified using post-hoc image analysis. To quantify head and neck injury potential, biomechanical measures based on headform acceleration and neck force/moment are measured. These biomechanical measures, through comparison with established human tolerance curves, can estimate the risk of severe life threatening and/or mild diffuse brain injury and osteoligamentous neck injury. To our knowledge, the presented test-bed is the first developed specifically to assess biomechanical effects on head and neck injury relative to helmet fit and retention.

Using an anthropometric head and neck, optical fiber-based fit force transducers, an array of head acceleration and neck force/moment transducers, and a dual high speed camera system, we present a test bed to study helmet retention and effects on biomechanical measures of head and neck injury secondary to head impact.

测试床, 检查头盔的拟合和保留, 以及在模拟撞击时头颈部损伤的生物力学措施

Conventional wisdom and the language in international helmet testing and certification standards suggest that appropriate helmet fit and retention during ...

Development of an Uncomplicated Mild Traumatic Brain Injury Model Modified by Weight-Drop Method and Evidenced by Magnetic Resonance Imaging

Mild traumatic brain injury (mTBI), known as concussion, accounts for more than 85% of brain injuries globally. Specifically, uncomplicated mTBI showing negative findings in routine clinical imaging in the acute phase hinders early and appropriate care in these patients. It has been acknowledged that different impact parameters may affect and even accelerate the progress of subsequent neuropsychological symptoms following mTBI. However, the association of impact parameters during concussion to the outcome has not been extensively examined. In the current study, an animal model with closed-head injury (CHI) modified from the weight-drop injury paradigm was described and demonstrated in detail. Adult male Sprague-Dawley rats (n = 20) were randomly assigned to CHI groups with different impact parameters (n = 4 per group). Longitudinal MR imaging studies, including T2-weighted imaging and diffusion tensor imaging, and sequential behavioral assessments, such as modified neurological severity score (mNSS) and the beam walk test, were conducted over a 50-day study period. Immunohistochemical staining for astrogliosis was performed on day 50 post-injury. Worse behavioral performance was observed in animals following repetitive CHI compared to the single injury and sham group. By using longitudinal magnetic resonance imaging (MRI), no significant brain contusion was observed at 24 h post-injury. Nevertheless, cortical atrophy and alteration of cortical fractional anisotropy (FA) were demonstrated on day 50 post-injury, suggesting the successful replication of clinical uncomplicated mTBI. Most importantly, changes in neurobehavioral outcomes and image features observed after mTBI were dependent on impact number, inter-injury intervals, and the selected impact site in the animals. This in vivo mTBI model combined with preclinical MRI provides a means to explore brain injury on a whole-brain scale. It also allows the investigation of imaging biomarkers sensitive to mTBI across varying impact parameters and severity levels.

Here, we present a protocol to establish a closed-head injury animal model replicating the neuroimage outcome of uncomplicated mild traumatic brain injury with the preserved brain structure in the acute phase and long-term brain atrophy. Longitudinal magnetic resonance imaging is the primary method used for evidence.

开发一种通过重量下降法修改并通过磁共振成像验证的简单轻度创伤性脑损伤模型

Mild traumatic brain injury (mTBI), known as concussion, accounts for more than 85% of brain injuries globally. Specifically, uncomplicated mTBI showing ...

修改落塔冲击试验为美国橄榄球头盔

摘要

探索更多视频

此视频中的章节

在使用功能性磁共振成像和头部撞击遥测系统的青年与体育有关的震荡影响的调查

实验室落塔的粉尘聚集在碰撞早期太阳系的实验模拟

视觉训练方法体育震荡缓解与管理

单侧颈脊髓损伤的挫伤模型，利用无限的地平线冲击

数据采集协议确定嵌入式灵敏度功能

控制下冲击头冲击的活体协议对现场研究数据的验证

柔性单向复合层压板的切割程序、拉伸测试和老化

方法和股骨骨折测试在横盘整理的秋天在臀部位置检测的夹具

测试床, 检查头盔的拟合和保留, 以及在模拟撞击时头颈部损伤的生物力学措施

开发一种通过重量下降法修改并通过磁共振成像验证的简单轻度创伤性脑损伤模型

修改落塔冲击试验为美国橄榄球头盔

摘要

探索更多视频

此视频中的章节

在使用功能性磁共振成像和头部撞击遥测系统的青年与体育有关的震荡影响的调查

实验室落塔的粉尘聚集在碰撞早期太阳系的实验模拟

视觉训练方法体育震荡缓解与管理

单侧颈脊髓损伤的挫伤模型，利用无限的地平线冲击

数据采集​​协议确定嵌入式灵敏度功能

控制下冲击头冲击的活体协议对现场研究数据的验证

柔性单向复合层压板的切割程序、拉伸测试和老化

方法和股骨骨折测试在横盘整理的秋天在臀部位置检测的夹具

测试床, 检查头盔的拟合和保留, 以及在模拟撞击时头颈部损伤的生物力学措施

开发一种通过重量下降法修改并通过磁共振成像验证的简单轻度创伤性脑损伤模型

数据采集协议确定嵌入式灵敏度功能