Stretch R A
Sport Bureau, University of Port Elizabeth, South Africa.
J Sports Sci. 2000 Dec;18(12):959-64. doi: 10.1080/026404100446766.
To determine whether the helmets currently used by cricket batsmen offer sufficient protection against impacts of a cricket ball, the impact absorption characteristics of six helmets were measured using the drop test at an impact velocity equivalent to a cricket ball with a release speed of 160 km x h(-1) (44.4 m x s(-1)). An accelerometer transducer attached to a 5.0 kg striker was dropped from a height of 3.14 m onto the batting helmets to measure the impact characteristics at the three different impact sites: right temple, forehead and back of the helmet. These data were further expressed as a percentage above (-) or below (+) the recommended safety standard of 300 g. The results indicate that the force absorption characteristics of the helmets showed inter- and intra-helmet variations, with 14 of the 18 impact sites (66.7%) assessed meeting the recommended safety standards. Helmets 1, 2 and 4 succeeded in meeting the safety standards at all impact sites; helmets 5 and 6 both failed at the back and forehead, while helmet 3 failed at all impact sites. These differences were due to the structure and composition of the inner protective layer of the helmets. The helmets that succeeded in meeting the standards were made with a moulded polystyrene insert, a heat-formed ethylene vinyl acetate (EVA) insert, or EVA with a relatively high density that allows a minimal amount of movement of the helmet at ball impact.
为了确定板球击球手目前使用的头盔是否能为抵御板球撞击提供足够的保护，使用落锤试验，以相当于释放速度为160 km x h(-1)（44.4 m x s(-1)）的板球的撞击速度，测量了六种头盔的冲击吸收特性。将一个连接到5.0 kg撞锤上的加速度计传感器从3.14 m的高度落到击球头盔上，以测量在三个不同撞击部位（右太阳穴、前额和头盔后部）的撞击特性。这些数据进一步表示为高于（-）或低于（+）300 g的推荐安全标准的百分比。结果表明，头盔的吸能特性在头盔之间和头盔内部存在差异，在评估的18个撞击部位中有14个（66.7%）符合推荐安全标准。头盔1、2和4在所有撞击部位均符合安全标准；头盔5和6在后部和前额均未通过，而头盔3在所有撞击部位均未通过。这些差异是由于头盔内部保护层的结构和组成造成的。成功符合标准的头盔是由模制聚苯乙烯内衬、热成型乙烯-醋酸乙烯酯（EVA）内衬或具有相对高密度的EVA制成的，这种材料在球撞击时能使头盔的移动量最小。
