Sarron Jean-Claude, Dannawi Marwan, Faure Alexis, Caillou Jean-Paul, Da Cunha Joseph, Robert Roger
Direction Centrale du Service de Santé des Armées, Action Scientifique et Technique--Bureau recherche (DCSSA/AST/REC), France.
J Trauma. 2004 Aug;57(2):236-42; discussion 243. doi: 10.1097/01.ta.0000133575.48065.3f.
Most military helmets are designed to prevent penetration by small firearms using composite materials in their construction. However, the transient deformation of the composite helmet during a non penetrating impact may result in severe head injury.
Two experimental designs were undertaken to characterize the extend of injuries imparted by composite panels using in protective helmets. In the first series, 21 dry skulls were protected by polyethylene plates, with gaps between the protective plate and skull ranging from 12 to 15 mm. In another design, using 9 cadavers, heads were protected by aluminum, aramid, or polyethylene plates. Specimens were instrumented with pressure gauges to record the impact response. The ammunition used in these experiments was 9 mm caliber and had a velocity of 400 m/s. A macroscopic analysis of the specimens quantified fractures and injuries, which were then related to the measured pressures.
Protective plates influenced both the levels of injury and the intracranial pressure. Injuries were accentuated as the plates was changed from aluminum to composite materials and ranged from skin laceration to extensive skull fractures and brain contusion. Fractures were associated with brain parenchymal pressures in excess of 560 kPa and cerebrospinal fluid pressure of 150 kPa. An air gap of a few millimeters between the plate and the head was sufficient to decrease these internal pressures by half, significantly reducing the level of injury.
Ballistic helmets made of composite materials could be optimized to avoid extensive transient deformation and thus reduce the impact and blunt trauma to the head. However, this deformation cannot be completely removed, which is why the gap between the helmet and the head must be maintained at more than 12 mm.
大多数军用头盔旨在通过在其结构中使用复合材料来防止小口径火器的穿透。然而，复合头盔在非穿透性撞击过程中的瞬态变形可能会导致严重的头部损伤。
进行了两项实验设计，以表征用于防护头盔的复合板造成的损伤程度。在第一个系列中，21个干燥的颅骨用聚乙烯板保护，保护板与颅骨之间的间隙为12至15毫米。在另一个设计中，使用9具尸体，头部用铝、芳纶或聚乙烯板保护。标本安装了压力计以记录撞击响应。这些实验中使用的弹药为9毫米口径，速度为400米/秒。对标本进行宏观分析以量化骨折和损伤，然后将其与测量的压力相关联。
防护板影响损伤程度和颅内压。随着防护板从铝质材料更换为复合材料，损伤加剧，范围从皮肤撕裂到广泛的颅骨骨折和脑挫伤。骨折与超过560千帕的脑实质压力和150千帕的脑脊液压力相关。防护板与头部之间几毫米的气隙足以将这些内部压力降低一半，显著降低损伤程度。
由复合材料制成的防弹头盔可以进行优化，以避免广泛的瞬态变形，从而减少对头部的撞击和钝性创伤。然而，这种变形无法完全消除，这就是为什么头盔与头部之间的间隙必须保持在12毫米以上的原因。
