基于数字仿真模型及交通事故重建的行人下肢损伤机制研究

Abstract: The pedestrian lower limb is vulnerable to trauma and causing deformity and disability in traffic accident. The trauma mechanism plays a key role in the case clarification and fact determination, which is one of the most difficult problems in the forensic identifications. The motion capture technology, multi-body model and finite element (FE) simulation provides new approaches for the mechanism exploration. Based on the preliminary reconstructed FE model of lower limb, this project will generate more accurate 3D structures of bones by original CT/MRI data and improve the 3D model of ligaments and muscular tissues around the long bones. Then verify the validation of the FE model with published literature data and real case materials. By loading both the real accident data and human lower limb motion capture data on the pedestrian-vehicle multi-body model, the traffic accident process was reconstructed. The kinematic parameters of multi-body model simulation results are loaded on the FE model of lower limb to analyze the injury mechanisms. By parameterizing the key factors causing the trauma including the external forces, the motion state and the physiological status of the lower limb, the parameter combinations of trauma causes were loaded onto the new limb FE model to run nonlinear and large deformation computation, and to study the trauma biomechanical response under different loading conditions. After the computation we will analyze the relationship between traumas of bones, ligaments, muscles and the stress/strain varieties and explore the connection law between stress/strain responses and parametric loading conditions. And we will explore the obvious distinctions among common trauma (impact injury, run-over injury or tumbling injury) in forensic practices, to recognize the trauma mechanism laws quantitatively and establish the trauma mechanism assessment system of the lower limb.

摘要：交通事故中行人下肢易受伤而致畸、致残，其损伤机制是查明案情、案件定性的关键，是法医学鉴定的难点问题之一。人体运动捕捉技术、多刚体及有限元仿真已成为损伤机制研究的新方法。本项目基于前期研发的下肢有限元模型，进一步完善骨骼、韧带、肌肉的3D模型，应用文献数据及真实案例验证模型的有效性。通过采集交通事故数据、结合人下肢运动状态记录数据，应用多刚体模型仿真交通事故过程，并提取多刚体仿真的下肢损伤参数，加载于下肢有限元模型上进行下肢损伤机制重建及分析。通过对外力作用、下肢运动状态以及下肢组织材料属性的参数化加载，求解不同致伤条件下肢损伤生物力学响应，研究骨骼、韧带、肌肉在参数化载荷下的外力-应变-损伤的响应关系，统计应力/应变响应与参数化载荷间的规律，研究常见损伤（碰撞伤、碾压伤、摔跌伤）成伤机制的差异，从而定量化研究下肢不同损伤的发生规律，建立以参数化有限元仿真为基础的下肢损伤机制评估体系。

法医学鉴定实践中下肢易受伤而致畸、致残，其损伤机制、致伤方式是查明案情、案件定性的关键，是法医学鉴定的难点问题。当前人体运动捕捉技术、激光扫描技术、多刚体及有限元仿真已成为损伤机制研究的新方法，但在法医学领域应用极少。课题应用了无人机倾斜摄影技术构建交通事故大现场模型、3D 激光扫描技术构建车辆变形构模与有限元车辆模型、三维面结构光扫描技术结合数字近景摄影测量法及虚拟解剖技术构建完整人体损伤模型、基于冲量/动量原理和多刚体动力学法的交通事故数字化重构、基于有限元法的交通事故损伤数字化重构，以及进行人体材料测试方法研究，以研究人体下骑行/推行的交通行为方式、二轮车人员驾乘关系分析、下肢高坠/碰撞伤机制、骨盆碰撞/碾压伤机制、人体软组织材料属性等科学问题。结果表明，数字仿真模型重建的生物力学证据能够辅助法医学鉴定实践，能够用于分辨特定的下肢损伤机制，辅助致伤方式的分析；数字仿真模型所保留的人体损伤、现场痕迹、车辆痕迹等三维可视化信息，具有永久保存、直观易懂、易于复制等特点，作为证据形式呈现具有较大优势；基于数字仿真模型的案例分析数据更加量化客观，对于经典法医学因果关系分析可提供量化数据，减少鉴定人的主观影响。本项目成功解决了多起复杂交通事故案例鉴定，课题组目前已发表论文10篇（SCI论文6篇），申请发明专利2项，实用新型2项（已授权），国内外会议作大会报告2人次，辅助培养硕士研究生5名。