6岁儿童腹部有限元建模及碰撞响应分析

发布时间：2018-05-07 23:17

本文选题：车辆安全 + 腹部损伤　；参考：《天津科技大学》2012年硕士论文

【摘要】：根据国家公安部交通管路局提供的数据显示,我国每年有1.85万个儿童死于交通安全事故,而去年德国在车内死亡的儿童仅76人。我国儿童在交通事故中的死亡率是美国的2.6倍,欧洲的2.5倍,己成为14岁以下儿童的第一死因,故有必要研究儿童胸腹部在碰撞中的损伤机理。在交通事故中,儿童乘员在约束系统的约束下,4岁以上儿童乘员腹部是继头部之后最易受伤的部位,这主要是因为4岁以上儿童在乘车时,使用成人使用的车辆安全带的比例较大,可是儿童的髂骨上前骨棘不发达,不能使腰带准确定位,在受到碰撞冲击时,腰带易从髋部滑向腹部而压迫腹部,导致腹部的内脏器官由于受压而受伤。因受到伦理学等社会因素的影响,儿童尸体实验数据极少,国际上主要采用有限元碰撞仿真实验研究碰撞过程中儿童的碰撞响应。而具有实际解剖学结构的高生物仿真度的有限元模型是碰撞仿真实验的基础。鉴于此,本研究构建高生物仿真度的儿童有限元模型,用于研究6岁儿童腹部损伤机理极有重要意义。本研究以6岁儿童腹部真实解剖学CT扫描图片为基础,应用Mimics软件提取腹部几何特征参数,并且运用逆向工程软件Geomagic对初步几何模型进行处理、划分曲面片,生成儿童腹部的几何模型。借助TrueGrid和HyperMesh软件对几何模型进行网格划分和网格优化,构建完整的腹部模型。该模型包括骨骼,肌肉,韧带等。骨骼包括腰椎(L1-L5),椎间盘。肌肉包括腹横肌、腹内斜肌、腹外斜肌、腹横肌、竖脊肌、腰大肌、腰方肌,膈肌。器官包括肝脏,肾脏,胃,脾。模型中的韧带、膈肌、腹直肌、胃采等用壳单元来模拟,其余组织均采用8节点6面体实体单元模拟。整个腹部模型共有165609个单元,196185个节点。模型采用弹性材料,弹塑性材料和粘弹性材料来模拟不同组织的性能。模型中的各个组织之间的连接是通过共同节点法和定义接触实现的。应用有限元分析软件LS-DYNA对模型做碰撞仿真实验。实验包括腰椎L4-L5段关节面载荷传递实验和腹部侧碰实验。仿真结果与尸体实验结果趋势较为一致,证明该研究所构建的6岁儿童腹部模型的有效性和可靠性。在腰椎L4-L5段的关节面载荷传递实验中,发现儿童的实验结果与成人有限元模型和尸体实验结果有些差别,儿童在L4-L5的关节面处的传递载荷要小于成人。此实验结果说明在外载荷作用下,儿童腰痛发生的概率要比成人小。综上所述,本研究所构建的6岁儿童腹部有限元模型为开展儿童腹部损伤机理的研究提供了可靠的理论依据,为推动我国儿童汽车安全法规的发展奠定了基础。
[Abstract]:According to data provided by the Traffic Management Bureau of the Ministry of Public Security, 18500 children die in traffic safety accidents every year in China, compared with 76 children killed in cars in Germany last year. The mortality rate of children in traffic accidents in China is 2.6 times that in the United States and 2.5 times in Europe. It has become the first cause of death of children under 14 years of age. Therefore, it is necessary to study the injury mechanism of children's chest and abdomen in collision. In traffic accidents, the abdomen of a child over 4 years of age is the most vulnerable area after the head, mainly because children over the age of 4 are travelling by car. The proportion of vehicle seat belts used by adults is high, but the iliac spine of children is underdeveloped and cannot accurately locate the belt. When it is hit by a collision, the belt is prone to slide from the hip to the abdomen and oppress the abdomen. The visceral organs of the abdomen are injured by compression. Due to the influence of social factors such as ethics, there are very few experimental data on children's cadavers. In the world, finite element collision simulation experiments are mainly used to study the collision response of children in the process of collision. The finite element model with actual anatomical structure is the foundation of collision simulation experiment. In view of this, it is of great significance to construct a high biosimulation finite element model for studying the mechanism of abdominal injury in children aged 6 years. Based on the CT scanning images of the true anatomy of abdomen in children aged 6 years, the geometric parameters of abdomen were extracted by Mimics software, and the initial geometric model was processed by reverse engineering software Geomagic. Generate a geometric model of the child's abdomen. A complete abdominal model is constructed by using TrueGrid and HyperMesh software to mesh and optimize the geometric model. The model includes bones, muscles, ligaments and so on. Bones include the lumbar vertebrae L 1-L 5 suture, intervertebral disc. Muscles include abdominal transverse muscle, internal oblique muscle, external oblique muscle, transverse muscle, erector muscle, psoas major muscle, psoas quadrate muscle, diaphragm muscle. Organs include liver, kidney, stomach and spleen. The ligament, diaphragm, rectus abdominis and stomach were simulated by shell unit, and the other tissues were simulated by 8-node 6-hedron solid unit. The whole abdominal model has 165,609 units and 196185 nodes. Elastic materials, elastoplastic materials and viscoelastic materials are used to simulate the properties of different microstructures. The connection between the organizations in the model is realized by common node method and definition contact. The finite element analysis software LS-DYNA is used to simulate the model. The experiment includes the load transfer experiment of lumbar L4-L5 joint surface and the abdominal side impact experiment. The simulation results are consistent with the results of cadaveric experiments, which proves the validity and reliability of the abdominal model of 6 years old children. In the load transfer experiment of L4-L5 segment of lumbar vertebrae, it was found that the experimental results of children were different from those of adult finite element model and cadaveric test, and the transfer load of children at the articular surface of L4-L5 was smaller than that of adults. The results show that the incidence of low back pain in children is lower than that in adults. To sum up, the abdominal finite element model of 6-year-old children constructed in this paper provides a reliable theoretical basis for the study of the mechanism of abdominal injury in children, and lays a foundation for the development of car safety regulations for children in China.
【学位授予单位】：天津科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R726.5

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