基于软组织材料本构模型寻优的交通事故钝性肝脏损伤机理研究

Liver is one of the most vulnerable organs suffering abdominal blunt injuries in vehicle accident and liver injuries are usually associated with high fatality risk. However, the blunt liver injury mechanism is still not clear due to the complexity in the physiological and mechanical characteristics of the human liver and the lack of knowledge on the material property of liver soft tissue. Therefore the current project aims to investigate the blunt liver injury mechanism by coupling the optimizing of material constitutive of liver soft tissue, reconstruction of real road traffic accident and numerical analysis of human blunt liver injury. Firstly, a mathematical material model of the liver soft tissue is derived by optimizing of its material property via physical material tests of both porcine liver soft tissue and organs and numerical simulations of these tests. Then a numerical human liver model, which can be used for predicting the liver injuries, is developed based on the optimal mathematical material model of the liver soft tissue. Secondly, the traffic accident cases with typical liver injuries are reconstructed using the defined numerical human liver model to investigate the dynamic responses and the injuries of the liver under blunt impact loading. Thirdly, car-to-pedestrian and car-to-car impact simulations under multiple loading conditions are constructed to study the influence of blunt impact loading to liver injuries. The simulation results are then employed to investigate the mechanism of blunt liver injury in vehicle crash accidents. Finally an evaluation function of the blunt liver injury risk is established based on the key parameters, including the impact velocity, loading orientation, loading area and impact force, which have a significant influence on blunt liver injury risk. The findings of this project could provide basic biomechanical knowledge and important technical references for the research of vehicle safety design and road traffic injury prevention.

肝脏是人体腹部钝性冲击中易受伤的器官，其损伤是引起交通事故伤亡的主因之一。由于肝脏组织复杂的生理和力学响应特征，其材料力学特性还未被充分掌握，钝性冲击下的肝脏损伤机理亦未被完全认知。本项目提出结合“肝脏软组织材料本构模型寻优-真实道路交通伤事故重建-人体肝脏损伤数值分析”的方法进行钝性肝脏损伤机理研究。研究内容包括：采用猪肝脏进行软组织材料力学实验和整体加载实验，结合数值仿真寻优最佳材料本构模型，获取能精确反映肝脏力学响应特性的人体数值模型；重构典型交通事故肝脏损伤，研究钝性冲击下的肝脏动力学响应及损伤参数；建立多工况的车-行人和车-车碰撞数值分析模型，研究冲击载荷对肝脏损伤参数的影响，阐明汽车碰撞事故中的钝性肝脏损伤机理；基于碰撞速度、载荷方向、受力面积和碰撞力等构建肝脏损伤风险评价函数P=f(v,c,s,f)。研究成果可为车辆被动安全设计及交通伤防护技术研究提供生物力学基础与技术参考。

道路交通事故所致人员伤亡已成为威胁人类安全的一大公害，全世界每年约有130万人死于道路交通事故。人体腹腔由于缺乏骨骼结构的保护，其损伤在交通事故中较为常见，而肝脏是人体腹部最大的器官，也是交通事故中容易受损的器官，其损伤在腹部损伤中占很大比重，且死亡率高于其他器官的损伤。针对交通事故中人体钝性肝脏损伤研究在材料本构模型、损伤机理、评价方式等方面的不足，本项目首先开展了一系列的动物（猪）肝脏的真实生物力学实验，并通过采取不同的实验速度，深入观察和分析了肝脏在动静态载荷条件下的生物力学特性；将实验数据与多种相关材料本构模型进行拟合对比，确定了其材料特性参数，并将其用于已有的人体胸腹部有限元数值模型中，为后续模拟其在受到车辆冲击时的损伤机制与特征奠定了基础；然后，由于人体肝脏有大部分处于胸腔内部，在受到冲击，如行人与车辆碰撞时，胸腔结构所受载荷条件可能直接影响内部脏器的损伤响应，因此本项目基于真实的人车碰撞事故案例，对我国比较普及的微型乘用车的前部结构及碰撞速度等因素对于肝脏所处胸腹部动力学及损伤响应的影响进行了深入研究；最后，在借鉴以上工作的基础上，本项目亦开展了部分人体颅脑组织生物力学的研究工作，主要集中在针对颅脑界面模拟方式和脑组织材料参数对脑组织响应的影响并对现有商业模型进行修正，及采用有限元-多体耦合模型的方法提升行人事故重建中的颅脑组织损伤响应预测和评价精度。本次课题的研究工作为车辆被动安全设计及人体肝脏/颅脑交通伤防护技术提供了有价值的生物力学基础和技术参考。