汽车侧面碰撞乘员生物力学响应与损伤评价研究

1、博士学位论文汽车侧面碰撞乘员生物力学响应与损伤评价研究作学指所者科导在姓专教学名 业 师 马正伟 车辆工程 陈吉清 教授 院 机械与汽车工程学院2015年7月 论文提交日期 Study on the Biomechanical Responses and InjuryAssessment of the Occupant in Automobile Side ImpactsA Dissertation Submitted for the Degree of Doctor of PhilosophyCandidate ：Ma ZhengweiSupervisor ：Prof. Chen Jiqin

2、gSouth China University of TechnologyGuangzhou, China 摘 要汽车产品在为人类社会提供便利的同时，伴随发生的汽车碰撞事故也造成了大量的人员伤亡和财产损失。根据世界卫生组织最近一次的数据统计，全球每年有120多万人死于道路交通事故，有2000-5000万人在事故中受到伤害，造成的经济损失达5000多亿美元。侧面碰撞是汽车碰撞事故中一种十分常见并且非常危险的事故形式。相比正面碰撞，侧面碰撞由于结构强度薄弱、吸能部件较少，并且车门与乘员之间距离有限，更容易造成严重的乘员伤亡。汽车碰撞安全研究的目的是为了保证人的安全，汽车碰撞安全性能的高低也主要通过

3、碰撞过程中乘员的伤害程度来评价。因此，深入研究侧面碰撞过程中人体各个部位的生物力学响应、损伤机理以及损伤耐受限度，对于指导汽车结构安全设计，改进汽车碰撞安全评价标准，以及提高侧面碰撞乘员损伤防护水平，都具有非常重要的现实意义和工程应用价值。通过对侧面碰撞人体损伤生物力学的研究背景、基本理论以及国内外研究现状进行综述，指出了当前侧面碰撞安全与人体损伤生物力学领域存在的不足，特别是国内相关方面研究的不足，并由此提出论文的研究内容和技术路线。首先，在深入理解人体解剖学结构以及有限元理论的基础上，基于中国50百分位男性志愿者的医学影像数据，建立了新一代、更高精度的乘员生物力学模型；与之前模型相比，新版

4、乘员生物力学模型具有更加精细、更加真实的人体细节组织结构，模型在软组织建模、组织材料本构、关节连接、颅骨-颅脑系统和心脏-主动脉系统的流固耦合接触关系等方面进行了很大的改进和优化。然后，根据ISO/TR 9790技术规程推荐的人体模型侧面碰撞仿生可靠性验证实验和评价方法，对乘员生物力学模型进行了多种碰撞条件下整体和局部的侧面碰撞仿生可靠性验证与评价。结果表明：乘员生物力学模型具有良好的侧面碰撞仿生可靠性，能够用于任何侧面碰撞条件下乘员各部位的生物力学响应与损伤机理研究。利用已构建并经过验证的乘员生物力学模型开展不同角度侧面碰撞下乘员各部位的生物力学损伤研究。首先，根据FMVSS 201U法规选

5、取某自主品牌SUV 侧面A 柱和B 柱的两个内饰参考点，对比分析了侧面斜置碰撞和侧面垂直碰撞条件下乘员头部的脑组织损伤。结果表明：侧面斜置碰撞下乘员头部脑组织损伤更严重；乘员头部与内饰件碰撞过程中，脑组织呈典型的碰撞对侧伤分布模式，损伤部位主要集中在碰撞对侧大脑、小脑、脑干的交界区域；A 柱参考点不同水平角度和俯仰角度下乘员颅脑损伤的对比分析表明，头部脑组织损伤对于碰撞水平角度的变化更为敏感。针对侧面碰撞事故中致死率最高的创伤性主动脉破裂（TRA ），深入剖析了人体主动脉的解剖学结构以及TRA 的损伤机理。通过构建各向同性线弹性和各向正交异性线弹性两种主动脉材料本构的乘员生物力学模型，开展胸部

6、侧面垂直碰撞和侧面斜置碰撞下主动脉损伤的对比研究。研究结果表明：主动脉采用不同的材料本构模型对模型胸部侧面碰撞的整体响应和损伤没有影响，但主动脉的应变响应存在差异，采用各向正交异性线弹性材料的主动脉对于碰撞载荷的响应更为敏感；相同侧面冲击能量下，侧面斜置碰撞造成的肋骨以及内脏组织损伤程度也比侧面垂直碰撞更严重，但侧面垂直碰撞造成的胸部主动脉的损伤比侧面斜置碰撞更严重；两种侧面碰撞条件下胸腔和主动脉的运动变形不同是导致主动脉损伤存在差异的主要原因。针对侧面碰撞事故中极易受到伤害的骨盆部位，构建了四种不同类型的乘员骨盆生物力学模型（V-Hex 模型、C-Hex 模型、V-HS 模型和C-HS 模型

7、）。通过不同加载条件下骨盆模型响应精度的对比分析发现：皮质骨变厚度分布的全六面体单元骨盆模型（V-Hex 模型）具有最高的仿真准确度，该模型真实模拟了骨盆的微观结构，能够在降低皮质骨厚度的同时，同步增大骨髓腔内松质骨的范围，可以真实地反映人体老化过程中骨骼内部皮质骨和松质骨的变化；但由于模型更精细，所需计算量比较大，不适于较大规模的模型计算。通过不同皮质骨厚度和不同弹性模量下的损伤研究发现：皮质骨厚度和弹性模量对于骨盆侧面碰撞损伤具有重要影响；老年人由于骨质钙化，皮质骨厚度变薄，弹性模量降低，在侧面碰撞事故中更容易发生骨盆骨折。最后，在C-NCAP 侧面碰撞实验规程的框架下，利用乘员生物力学模

8、型对某自主品牌SUV 的侧面碰撞安全性进行评价，并与样车侧面碰撞试验中ES-II 假人的评价结果进行对比。结果表明：论文提出的基于乘员生物力学模型的汽车碰撞安全评价方法在理论和技术上切实可行；乘员生物力学模型的损伤评价结果比假人模型预测结果更加清楚、详细，用于汽车安全结构改进更加有针对性，因此利用乘员生物力学模型进行汽车碰撞安全设计和评价，相对传统方法具有独特的优势和先进性。论文的研究工作对于促进我国汽车安全设计与乘员损伤评价、完善汽车安全法规具有重要的借鉴意义和实用价值。关键字：汽车；侧面碰撞；乘员损伤；生物力学响应；损伤评价IIABSTRACTAutomobile products hav

9、e provided great convenience for human society. However, the loss of casualties and property caused by automobile collisions is also very huge. According to the latest statistics of the World Health Organization, there were more than 1.2 million people being killed and 20-50 million people geting hu

10、rt in road traffic accidents every year, which meaned an economic loss of more than 500 billion dollar. The side collisions is a kind of particularly frequent and dangerous form of vehicle accidents. Compared with the frontal collisions, side collisions can lead to more serious casualties owing to t

11、he weak strength of the side structure, the little energy absorption and the limited space between occupants and the vehicle door. As is well known to all, the ultimate purpose of vehicle safety design is to ensure human safety. And the performance of vehicle crash safety mainly depends on the injur

12、y severity of the occupant in the crash. Therefore, the in-depth study of the biomechanical responses, injury mechanism and injury tolerance in defferent parts of the human body in side impacts is of vital practical significance and engineering application value to the design of vehicle structure sa

13、fety, the improvement of vehicle safety assessment criterion and occupants protection.Limitations of the study on side impact and human injury biomechanics, in particular for the shortages of the related study in China, are summaried by reviewing the research background, the basic theory and the res

14、earch status at home and abroad, followedby the contents and technique route of this study. First of all, a new verion of occupant biomechanical model with higher precision is developed based on the CT and MR image data of a volunteer representing the physical characteristics of the 50th percentile

15、Chinese male. Compared with the old one, the current occupant biomechanical model has more detailed and more realistic human body tissues, which can be observed in the creation of soft tissues, the optimization of constitutive material model, the modeling of articular joints, and the simulation of t

16、he fluid-struture interaction in the aortic system and the skull-brain system. Afterwards, the biofidelity of the occupant biomechanical model is analyzed and evaluated based on the PMHS (Past Mortal Human Subject tests of defferent parts of human body inIIIvarious side impact conditions provided by

17、 ISO-TR9790 procedures. The results show that the occupant biomechanical model developed in this study can possess a high level of biofidelity in side impacts. And it can feel up to the study of the biomechanical responses and injury mechanism for defferent body parts in any side impact conditions.B

18、ased on the occupant biomechanical model developed in this study, thestudy of the biomechanical injury for defferent body parts in defferent derection of side impact is performed. First, the traumatic brain injury (TBI of the occupant in oblique and perpendicular side impacts is discussed by the imp

19、act simulations of the occupants head model with the reference points on the surface of the interior part in the A pillar and B pillar according to FMVSS 201U regulation. The results indicate that the occupants brain injury in oblique side impact is more serious than that in perpendicular side impac

20、t. During the impact, the brains inury type presents an obovious pattern of contralateral injury distribution comparing to the impact position. The brains inury manly distributes on the connected regions of the brain, the cerebellum and the brain stem opposite to the impact position of the forehead.

21、 In addition, the sensitivity study of occupants brain injury in defferent horizontal and defferent pitch angels impacting on the A pillar demonstrated that the brains inury is more sensitive to the change of the horizontal impact angel.In view of the high fatality resulting in the traumatic rupture

22、 of the aorta (TRA in side collisions, the anatomical structure and injury mechanism of TRA is investigated in-depth. Ultilizing the occupant biomechanical models with isotropic linear elastic material model and orthotropic linear elastic material model of the aortic tissue, the injuries of the thor

23、ax and aorta in perpendicular and oblique side impacts are analyzed. The results reveal that the change of the aortic constitutive material model has few infulunce on the thoracic responses and injury. However, the longitudinal Lagrange strain responses of the descending thoracic aorta are distinctl

24、y not equal. Comparatively speaking, the model with orthotropic linear elastic aortic material model presents more sensitive to the change of side impact. Under the same impact energy, the fractures of the thoracic ribcage and injuryies of the internal organs in oblique side impact are much more ser

25、ious than those in perpendicular side impact. Nevertheless, the aortic injury in perpendicular side impact is more serious than that in oblique side impact. The difference of injury severity in the aorta can be accounted for the IVdifference of their movements and deformations during perpendicular a

26、nd oblique side impacts.Given that the occupants pelvis is very vulnerable to side collisions, four different occupants pelvic model with different modeling in the element type and thickness of the pelvis coritical bone (the V-Hex model, the C-Hex model, the V-HS model and the C-HS model are created

27、. Through the comparisons of the four models predictions under different loading conditions, it is found that the all-hex model with variable cortical bone thickness (the V-Hex model shows the highest accurancy in simulations. The V-Hex model accurantely models the microstructures of the pelvic bone

28、. In the V-Hex model, the cortical bone thickness can be thinned with the marrow cavity (the cancellous bone being enlarged at the same time. This phenomenon agrees with the bone mineral content alterations in older people. However, the V-Hex model may not be favorable for some applicat ions, in whi

29、ch the models element number is too large. Compared with other types of pelvic model, the computing time of the V-Hex model is much longer owing to the small element size in it. From sensitivity studies of the the pelvis responses and injuries to variations in pelvis cortical bone thickness, bone ma

30、terial properties, and loading conditions, it is found that alterations of the thickness and Youngs modulus of the cortical bone has a more significant effect on pelvis injury. Along with aging, the bone mineral density and cortical bone Youngs modulus of the pelvis is gradually reducing. Meanwhile,

31、 the cortex thickness is thinning while the marrow cavity is enlarging. There fore, older people are more susceptible to severe injury in side impacts.Finally, the assessment of a SUVs safety performance in side impact is carried out ultalizing the occupant biomechanical model according to the side

32、impact regulations in C-NCAP (China-New Car Assessment Program. Moreover, the assessment results of the occupant biomechanical model are compared with those of the ES-II dummy in the side impact test of the sample car. The reaults indicate that the assessment metod of vehicle crash safety on the bas

33、is of the occupant biomechanical model in this tudy is feasible on the theory and technology. The assessment results of the occupant biomechanical model are much more detailed and clear than those of the mechanical dummy, and are more targetd to the improvement of automobile structure safety. Theref

34、ore, the design and assessment of vehicle crash safety based on the occupant biomechanical model have a unique advantage andVadvancement comparering to the traditional methods. In conclusion, the study in this paper will provide important significance and practical value to the improvement of vehicl

35、e safety design, occupants injury protection and automobile safety regulations.Keywords: Automobile; Side impact; Occupant injury; Biomechanical response; Injury assessmentVI目 录摘 要 . . I ABSTRACT . III第一章 绪论 . . 11.1 论文研究背景与意义 . 11.2 侧面碰撞生物力学损伤与安全法规标准 . 31.2.1 侧面碰撞与乘员损伤 . . 31.2.2 侧面碰撞乘员损伤评价标准 . . 6

36、1.2.3 侧面碰撞安全法规介绍 . . 111.3 侧面碰撞生物力学研究方法 . 141.3.1 事故损伤统计与分析 . . 141.3.2 生物样本实验 . . 151.3.3 机械模型实验 . . 161.3.4 数字模型仿真 . . 171.4 国内外研究进展 . 201.4.1 侧面碰撞PMHS 实验 . . 201.4.2 侧面碰撞生物力学模型 . . 241.5 目前存在的主要问题 . 271.6 论文主要研究内容与课题来源 . 28第二章 基于中国人体特征的侧面碰撞乘员生物力学模型 . 312.1 引言 . 312.2 有限元建模基本理论 . 312.2.1 显式积分算法 . . 312.2.2 常用单元类型 . . 322.2.3 常用材料类型 . . 342.3 模型建立方法与步骤 . 352.4 侧面碰撞乘员生物力学模型 . 372.4.1 头部生物力学模型 . . 382.4.2 躯干生物力学模型 . . 41VII2.4.3 其他部位生物力学模型 . . 462.4.5 模型中生物组织材料参数 . . 462.5 本章小结 . 50第三章 基于ISO/TR 9790的侧面碰撞乘员生物力学模型仿生可靠性验证 . . 513.1 引言 . 513.2 基于ISO/TR 9790技术规程