老龄和肥胖乘员有限元模型建模方法及损伤机理研究

发布时间：2018-05-31 21:57

本文选题：老龄乘员 + 肥胖乘员　；参考：《湖南大学》2014年博士论文

【摘要】：道路交通事故是造成人类伤亡的重要因素之一。每年有120万人死于道路交通事故,约2000万人遭受终身的伤残性伤害。随着汽车安全技术的不断发展以及乘员安全性问题逐步受到重视,驾乘人员的损伤防护技术取得了很大的进展,特别是50百分位成人的乘员保护技术已趋成熟。然而,相对于50百分位的成人,老龄人群和肥胖人群等特殊群体在汽车碰撞事故中更易遭受重伤和死亡。但是现有的碰撞测试假人和人体有限元模型等损伤评价工具,并没有考虑到人群中年龄和肥胖程度组成的多样性。由于医疗条件以及物质生活水平的提高,世界各国的老龄以及肥胖人群的所占比重呈现出逐渐增加的趋势。因此,老龄和肥胖乘员有限元模型的开发以及损伤机理研究已经成为汽车安全研究领域迫切需要解决的重要课题。本文在文献研究的基础上,利用人体测量学方法、统计学方法、网格变形技术、计算机仿真以及优化技术,分别对老龄和肥胖乘员有限元模型的建模方法以及损伤机理等进行了研究。研究工作的主要内容及创新点如下： 1、参数化的肋骨腔几何模型的建立。本研究通过收集大量的临床医用CT(Electronic Computer X-ray Tomography Technique)扫描数据,并进行了数据分割、指定位置标志点坐标数据获取以及Procrustes分析,建立了同一坐标系下的人体肋骨腔标志点空间坐标数据集。在此基础上,对标志点空间坐标数据集进行了主成分分析和多变量回归分析,建立了基于人体特征的参数化肋骨腔几何模型,并用于研究年龄、性别、身高以及BMI (Body Mass Index)对肋骨腔几何模型大小和形状的影响。结果表明,这些人体特征参数对肋骨腔几何模型均有显著性影响；同时,利用统计学方法建立了基于人体特征参数的肋骨横截面面积的线性混合模型。研究发现,除BMI外,其它的人体特征参数对肋骨横截面面积均具有显著性影响。该研究为后续建立参数化的人体有限元模型提供了三维数模基础。 2、开发出一套基于径向基函数理论的参数化网格变形技术。本研究利用基于样条曲线的几何变形方法对标志点空间坐标进行逼近,并用于对标志点坐标数据的分析,最终把参考空间里的坐标基准位置映射到新空间的目标位置。坐标映射的过程包括整体的平移、刚度旋转、缩放以及局部弯曲。通过该网格变形技术可以将基准模型与不同的目标模型联系起来,并运用该技术对人体骨骼模型进行了网格变形研究。结果表明该方法快捷有效,可为后续开展参数化人体有限元模型的研究提供技术基础。 3、提出了建立任意指定人体特征参数的乘员有限元模型的流程,并完成了指定人体特征的乘员有限元模型的验证工作。本研究首先利用丰田公司开发的第四代人体有限元模型,建立了人体外部轮廓与内部骨骼结构的混合几何模型；在此基础上,利用本文开发的网格变形技术,提出了一套建立参数化人体有限元模型的流程。其后,利用该流程建立了一个预先指定了人体特征的乘员有限元模型,并对该模型的有效性进行了验证。结果表明利用本文提出参数化人体有限元建模流程开发的模型具有较高的生物逼真度,因而可利用该流程自动生成任意指定人体特征参数的乘员有限元模型。这为研究汽车乘坐环境对特殊人群碰撞安全性的影响,提供了有效的新思路。 4、研究并分析了老龄人群的损伤机理以及年龄对人体肋骨骨折损伤风险的影响。为分析年龄对人体损伤的影响,本研究建立了指定人体特征参数条件下的胸部有限元模型。该模型经过严格的仿真碰撞验证,并与两具含有不同人体特征参数的尸体样本胸部撞击试验进行了对标。结果显示,建立的基于年龄特征的参数化胸部有限元模型具有较高的仿真度。为了探究与人体年龄相关的材料参数、几何模型以及组织结构属性对胸部生物力学特性的影响,对验证后的胸部有限元统计学模型进行参数化研究。结果表明,由于年龄增长而引起的胸部几何模型、肋骨材料参数以及肋骨骨密质厚度的变化量,导致胸部的线性刚度特性、肋骨骨密质的Von Mises应力和第一主应变呈现出不同的变化趋势；特别是,在冲击锤的撞击作用下,随着人体年龄的增长,胸部几何模型、肋骨材料参数以及肋骨骨密质厚度产生的复合影响会使得肋骨骨密质的Von Mises应力和第一主应变逐渐升高。考虑到随着人体年龄的增长,人体骨骼组织的失效应力和失效应变将逐渐减小,导致老龄人群在碰撞过程中将面临更大的胸部肋骨骨折损伤风险。 5、研究并分析了肥胖乘员的损伤机理以及肥胖对乘员损伤风险的影响。基于目前文献中仅存的少量肥胖人群碰撞试验数据,对上述新建的参数化的人体有限元模型分别进行了腹部安全带动态加载验证和尸体台车碰撞仿真碰撞验证。结果表明利用本文提出参数化人体有限元建模流程开发的肥胖人体模型具有较高的生物逼真度。在此基础上,再次利用上文新建的参数化人体有限元模型和网格变形技术,对人体各局部区域逐步变形,得到BM1分别是25kg/m2、30kg/m2、35kg/m2和40kg/m2的人体有限元模型,并用于研究在车辆正面碰撞过程中人体肥胖特征对乘员损伤响应的影响。结果表明,与非肥胖乘员相比,肥胖乘员额外增加的人体质量并由此导致了安全带更差的佩戴路径,使得其在正面碰撞事故中遭受更高的胸部以及下肢的损伤风险。本研究的结论可为以后的乘员约束系统设计开发提供相关的有用信息及理论依据。
[Abstract]:Road traffic accidents are one of the important factors that cause human casualties. 1 million 200 thousand people die of road traffic accidents every year, about 20 million people suffer life-long disability. With the continuous development of automobile safety technology and the safety of occupants, the protection technology of passengers and passengers has made great progress. The occupant protection technique of the 5 thousand divided adults has matured. However, special groups, such as the aged and the obese, are more likely to be severely injured and killed in car collisions compared to adults with 5 thousand points, but the existing damage assessment tools such as the collision test dummy and the human finite element model do not take into account the age of the population. The diversity of the degree of obesity. Due to the improvement of medical conditions and the level of material life, the proportion of older people in the world and the proportion of obese people are increasing gradually. Therefore, the development of the finite element model of the aged and obese occupants and the study of the damage mechanism have become urgent need to be solved in the field of automobile safety research. On the basis of literature research, this paper makes use of anthropometry, statistical method, grid deformation technology, computer simulation and optimization technology to study the modeling method and damage mechanism of the finite element model for aging and obese occupants respectively. The main contents and innovation points of the research work are as follows:
1, the establishment of a parameterized geometric model of the rib cavity. By collecting a large number of clinical medical CT (Electronic Computer X-ray Tomography Technique) scanning data, the data is divided, the coordinates of the location mark point coordinates are obtained and the Procrustes analysis is used to establish the space of the rib space of the human body in the same coordinate system. On this basis, the principal component analysis and multivariate regression analysis are carried out on the spatial coordinate data set of the mark point space. The geometric model of the parameterized rib cavity based on the human body features is established and used to study the influence of age, sex, height and BMI (Body Mass Index) on the size and shape of the geometric model of the rib cavity. These human characteristic parameters have a significant influence on the geometric model of the rib cavity. At the same time, a statistical method is used to establish a linear mixed model of the cross section area of the ribs based on the characteristic parameters of the body. It is found that the other human characteristic parameters have significant influence on the cross section area of the ribs except BMI. The parameterized human body finite element model provides the basis for three-dimensional numerical modeling.
2, a set of parameterized grid deformation technology based on radial basis function theory is developed. This study uses geometric deformation method based on spline curve to approximate the spatial coordinates of mark points, and is used to analyze the coordinate data of mark points. Finally, the coordinates of coordinates in the reference space are mapped to the target position of the new space. The process of shooting includes the translation of the whole, the rotation of the stiffness, the scaling and the local bending. Through the mesh deformation technology, the reference model can be connected with the different target models, and the mesh deformation of the human skeleton model is studied by this technique. The results show that the method is fast and effective and can be used for the subsequent development of the parameterized human body. The research of metamodel provides a technical basis.
3, the process of establishing a crew finite element model with any specific parameters of human body is proposed, and the verification of the crew finite element model with designated human features is completed. In this study, a hybrid geometric model of the external profile of the human body and the internal skeleton structure is established by using the fourth generation human body finite element model developed by the Toyota Corporation. On this basis, using the grid deformation technology developed in this paper, a set of process for establishing the parameterized human finite element model is proposed. After that, a crew finite element model with pre designated human features is established and the validity of the model is verified. The results show that the parameterized human body is limited by this paper. The model developed by the meta modeling process has a high biological fidelity, so it can automatically generate the crew finite element model of any specific human characteristic parameters by the process. This provides an effective new idea to study the impact of the vehicle riding environment on the safety of the special crowd.
4, we studied and analyzed the damage mechanism of the aged and the influence of age on the risk of human rib fracture. In order to analyze the influence of age on human injury, this study established a finite element model of the chest under the condition of designated human characteristic parameters. The model was verified by rigorous simulation collision and with two different human characteristics. The parameters of the body samples were tested in the chest impact test. The results show that the established age based parametric chest finite element model has a higher simulation degree. In order to explore the material parameters, geometric model and structure properties of the body age related material, the effects on the mechanical properties of the thoracic raw material and the verifying chest are found. The results show that the geometric model of the chest, the material parameters of the ribs and the thickness of the rib bone, resulting in the linear stiffness characteristics of the chest, the Von Mises stress of the rib bone density and the first principal stress change, in particular, in the flushing. With the impact of hammer, the Von Mises stress and the first principal strain of the rib bone density increase gradually with the growth of human age, the geometric model of the chest, the material parameters of the ribs and the thickness of the rib bone. Considering the age of the human body, the failure stress and failure strain of the human bone tissue will be considered. Gradually decreasing, the elderly population will face greater risk of chest rib fracture during the collision process.
5, the damage mechanism of the obese occupants and the effect of obesity on the risk of occupants' injury are studied and analyzed. Based on the data of the only small number of obese people in the literature, the dynamic loading verification of the abdominal safety belt and the collision simulation of the carcass car collision are verified by the new parameterized human finite element model. The results show that the obese human model developed by the parameterized human finite element modeling process has high biological fidelity. On the basis of this, the new parameterized human body finite element model and grid deformation technology are used again to form the body parts gradually, and the BM1 is 25kg/m2,30kg/m2,35kg/m2 and 40, respectively. The human body finite element model of kg/m2 is used to study the effect of human obesity on the occupant's damage response during the frontal crash of a vehicle. The results show that the extra body mass of the obese occupants, compared with the non obese occupants, leads to the worse wear path of the seat belt, which makes it higher in the frontal crash. Conclusion: the conclusion of this study can provide useful information and theoretical basis for future occupant restraint system design and development.
【学位授予单位】：湖南大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U467.14;U491.61

【共引文献】