Seifert Jack, Koser Jared, Shah Alok, Frazer Lance, Pintar Frank A, Yoganandan Narayan, Nicolella Dan, Bentley Timothy B, Stemper Brian D
Joint Biomedical Engineering Department, Marquette University and Medical College of Wisconsin, Milwaukee, USA.
Neuroscience Research Labs - Research 151, Zablocki VA Medical Center, 5000 W. National Ave, Milwaukee, WI, 53295, USA.
Ann Biomed Eng. 2025 Jul 14. doi: 10.1007/s10439-025-03797-w.
Body armor is used to protect the wearer from penetrating injuries. However, when the armor defeats the projectile, it deforms at high rates into the wearer, referred to as back face deformation (BFD). This deformation can cause a variety of superficial and internal injuries and consequently should be considered when designing body armor. However, current design standards do not adequately consider the effects of BFD, and new data are necessary to inform future design thresholds for BFD. The objective of this study was to develop blunt impact injury risk curves for in vitro thoraco-abdominal organs and determine their applicability in predicting in situ BABT injuries.
In vitro tests Healthy isolated liver and heart specimens were perfused and placed on a bed of gelatin underneath a drop tower and impacted with a 3-cm hemisphere impactor. Each organ was exposed to an incremental loading protocol, wherein initial displacement of penetration was 2 mm, and increased by 2 mm for each subsequent impact on the organ. Injury was defined as the presence of laceration. Injury probability curves were developed using a generalized mixed linear model (proc GENMOD). Univariate models were analyzed for predictive variables, including peak displacement, percent compression, and peak force. In situ tests An intact postmortem human subject (PMHS) was instrumented and subsequently impacted with an impactor that had a profile representative of BFD and a velocity of 65 m/s. One impact was aimed at the heart and one impact was aimed at the liver.
The final predictive models for isolated organ injuries demonstrated 50% probability of injury for impact displacement of 12.4 mm (95% CI [10.1 mm, 17.6 mm]) and 13.8 mm (95% CI [11.5 mm, 16.8 mm]) for the liver and heart, respectively. During the PMHS tests, total impactor displacement into the PMHS was 45.8 mm and 59.2 mm for the impacts aimed at the liver and heat, respectively. Post-rib fracture impactor displacement did correlate to the isolated organ risk curves, equating to an 88% and 86% of liver and heart injury risk, respectively. Despite high risk of injury for both organs, only the liver was lacerated, suggesting that isolated organ risk curves do not fully translate to in situ testing.
These experimental tests and developed risk curves can be used as validation and injury risk estimates for future isolated organ and whole body computational models. Simulated BFD impacts with PMHS tests highlight the complexity of BABT injury mechanisms and shows the significant anisotropy of the thoraco-abdominal region that should be considered when developing future protective equipment.
防弹衣用于保护穿戴者免受穿透性伤害。然而，当防弹衣抵御住射弹时，它会高速变形并冲向穿戴者，这被称为背面变形（BFD）。这种变形会导致各种体表和内部损伤，因此在设计防弹衣时应予以考虑。然而，当前的设计标准并未充分考虑背面变形的影响，需要新的数据来为未来背面变形的设计阈值提供参考。本研究的目的是建立体外胸腹器官钝性冲击损伤风险曲线，并确定其在预测原位弹道致腹部钝性创伤（BABT）损伤方面的适用性。
体外试验 健康的离体肝脏和心脏标本经灌注后置于落塔下方的明胶床上，用一个3厘米的半球形撞击器进行撞击。每个器官都接受递增加载方案，其中初始穿透位移为2毫米，随后每次对器官的撞击位移增加2毫米。损伤定义为出现撕裂伤。使用广义混合线性模型（proc GENMOD）建立损伤概率曲线。对单变量模型分析预测变量，包括峰值位移、压缩百分比和峰值力。原位试验 对一具完整的尸体（PMHS）进行仪器安装，随后用一个具有代表背面变形特征且速度为65米/秒的撞击器进行撞击。一次撞击针对心脏，一次撞击针对肝脏。
离体器官损伤的最终预测模型显示，肝脏和心脏的撞击位移分别为12.4毫米（95%置信区间[10.1毫米，17.6毫米]）和13.8毫米（95%置信区间[11.5毫米，16.8毫米]）时，损伤概率为50%。在尸体试验中，针对肝脏和心脏的撞击，撞击器进入尸体的总位移分别为45.8毫米和59.2毫米。肋骨骨折后的撞击器位移与离体器官风险曲线确实相关，分别相当于肝脏和心脏损伤风险的88%和86%。尽管两个器官的损伤风险都很高，但只有肝脏出现撕裂伤，这表明离体器官风险曲线并不能完全转化为原位测试结果。
这些实验测试和建立的风险曲线可用于验证未来的离体器官和全身计算模型，并估计损伤风险。尸体试验中的模拟背面变形撞击突出了弹道致腹部钝性创伤损伤机制的复杂性，并显示了胸腹区域显著的各向异性，在开发未来的防护装备时应予以考虑。
