儿童胸部有限元模型开发及损伤机理研究

发布时间：2018-04-27 16:49

本文选题：儿童安全 + 损伤生物力学　；参考：《湖南大学》2013年博士论文

【摘要】：在儿童意外伤害的研究中发现，儿童胸部遭受损伤时，容易形成严重损伤并伴有较高的死亡率。人体胸腔内保护着维持人体生命机能的呼吸和血液循环系统以及包括肝在内的一些其他重要腹部器官，因此，当儿童乘车时，需要对其胸部给予充分的保护。由于儿童与成人在解剖结构和材料特性上的差异，使得成人的胸部损伤准则和容忍极限并不适用于儿童。基于这些损伤准则和容忍极限开发出的成人约束系统也可能无法很好地保护儿童，甚至反而给儿童造成致命的伤害。因此，研究儿童胸部损伤准则、容忍极限及防护方法具有重要的现实意义。生物力学实验和计算机仿真模拟是研究人体损伤机理和容忍极限的常用方法。因此，本文在大量文献研究的基础上，开展了儿童胸部有限元建模及儿童胸部生物力学实验研究，并利用有限元分析方法对儿童胸部损伤机理、损伤准则和容忍极限及儿童胸部缩放响应数据进行了研究。由于缺少相应的儿童建模数据，，包括几何数据、材料数据以及验证数据，导致可用于儿童安全研究的详细儿童胸部模型十分缺乏。本文通过收集多个临床治疗中获得的儿童患者CT (Electronic Computer X-ray Tomography Technique)和MRI(Magnetic Resonance Imaging)图像，结合Hypermesh (10.0, Altair, Tory, MI)软件将多名患者的数据整合成标准的10岁儿童几何模型。利用ANSYS ICEM (ANSYS,Canonsburg, Pennsylvania, U.S.A)的Block-Controlled对骨骼和内脏进行了纯六面体网格划分。模型具有详细的儿童解剖学结构，包括皮肤、肋骨、肋软骨、心脏、肺、大血管、膈膜及腹部器官等等。各组织的的材料特性则基于国内外文献中成人模型的材料参数，利用比例缩放的方法获得。精确的儿童胸部力-变形响应数据是开发儿童有限元模型及儿童假人模型的关键数据之一。然而，由于伦理道德的限制，很难大量开展传统的尸体实验来获得儿童响应数据。本文再次利用临床治疗过程中获取的儿童CPR胸部响应数据对建立的有限元模型进行了静态验证、材料的参数化研究及边界加载条件的影响研究，这些研究有助于提高模型的生物逼真度，获得精确的儿童材料参数，为今后临床CPR获得更为精确的人体胸部响应数据提供指导。此外，结合儿童在临床CPR中加载和损伤情况，利用模型开展静态加载下的损伤分析，研究结果有利于提高模型在静态加载下的损伤预测能力。 CPR中的加载属于静态加载的范畴，若要将建立的儿童有限元模型用于汽车安全等高速冲击条件下的损伤研究，还需对模型进行动态响应的验证。基于目前国内外少量的与儿童胸部相关的尸体实验数据，对模型在撞击及斜拉式安全带加载下的动态响应进行了仿真分析。主要对比分析了仿真和实验中获得的胸部的力-变形响应及肋骨、内脏等的损伤情况，进一步验证了模型的生物逼真度。同时，损伤分析的结果表明成人胸部压缩量损伤准则和黏性损伤准则可用于儿童胸部损伤的预测，但儿童的损伤容忍极限值均要低于成人的容忍极限值。由于缺乏用于儿童模型验证的响应数据，目前的儿童假人模型及部分有限元模型验证工作中采用了比例缩放获得的数据。然而比例缩放获得的响应数据本身没有经过实验数据的验证，本文利用开发的有限模型仿真分析了模型在比例缩放条件下的响应情况，对比了模型胸部响应结果与缩放获得的胸部通道数据。同时，研究了肋骨骨密质杨氏模量对缩放结果的影响及摆锤质量、直径和初始撞击速度对胸部响应的影响。研究结果有利于提高缩放数据的准确性。最后，开展了儿童胸部尸体实验。设计了一种新的儿童胸部尸体实验方案，并利用Q6儿童假人对该实验方案进行了充分的验证。在此基础上，利用非新鲜的儿童尸体样本，开展了正式的儿童胸部尸体实验，获得了儿童胸部力-变形曲线。为今后进一步开展儿童胸部损伤生物力学研究奠定了基础。当今儿童意外伤害问题逐渐突出，开展儿童有限元建模和生物力学实验研究，有利于加快儿童数学模型及机械模型的发展，从而可通过利用这些儿童模型及生物力学实验了解儿童损伤机理并在此基础上开展损伤防护措施的研究，对儿童安全的提高具有重大的现实意义。
[Abstract]:In the study of accidental injuries in children, it is found that a child's chest injury is prone to severe injury and high mortality. The body's chest protects the respiratory and blood circulation system that maintains the human life function, as well as some other important abdominal organs, including the liver. Therefore, children need to have their breasts when they are riding in the car. Adequate protection. Due to differences in anatomical structure and material characteristics between children and adults, the guidelines and tolerance limits for adults' chest injuries are not applicable to children. The adult restraint systems developed based on these criteria and tolerance limits may not be well protected for children, and may even cause death to children. Therefore, it is of great practical significance to study children's chest injury criteria, tolerance limits and protection methods. Biomechanical experiments and computer simulation are the common methods to study the mechanism of human injury and tolerance limit. Therefore, on the basis of a large number of literature studies, the finite element modeling of children's chest and children's chest are carried out in this paper. The Biomechanical Experimental Study and the finite element analysis were used to study the mechanism of children's chest injury, the damage criterion and tolerance limit and the response data of the children's chest scaling.
The lack of appropriate child modeling data, including geometric data, material data, and validation data, leads to the lack of detailed children's chest models for child safety research. This article is based on the collection of CT (Electronic Computer X-ray Tomography Technique) and MRI (Magnetic Resonance) obtained in multiple clinical treatments. Imaging) images, combined with Hypermesh (10, Altair, Tory, MI) software to integrate the data of multiple patients into a standard 10 year old child geometric model. Using the ANSYS ICEM (ANSYS, Canonsburg, Pennsylvania, U.S.A) Block-Controlled to carry out a pure hexahedral mesh of the skeleton and viscera. The model has a detailed anatomical structure of children. Including skin, ribs, costal cartilage, heart, lung, large blood vessels, diaphragm and abdominal organs, and so on. The material properties of each tissue are based on the material parameters of the adult model in the domestic and foreign literature and are obtained by scaling.
Accurate children's chest force deformation response data is one of the key data for developing children's finite element model and children's fake model. However, because of ethical limitations, it is difficult to carry out a large number of traditional corpse experiments to obtain children's response data. This paper again uses the CPR chest response data obtained in the clinical treatment process to build the children's chest response data. Static verification, parametric study of materials and the influence of boundary loading conditions on the finite element model are carried out. These studies help to improve the biological fidelity of the model, obtain accurate parameters of the children's material, and provide guidance for more accurate human chest response data for future clinical CPR. In addition, children are in clinical CPR. In the case of loading and damage, the damage analysis under static loading is carried out by using the model. The research results are beneficial to improve the damage prediction ability of the model under static loading.
Loading in CPR belongs to the category of static loading. If we want to use the established children's finite element model to study the damage of automobile safety and so on at high speed, it is necessary to verify the dynamic response of the model. Based on a small amount of data related to the chest of children at home and abroad, the model is added to the impact and cable-stayed safety belt. The dynamic response was simulated and analyzed. The stress deformation response of the chest and the damage of rib and viscera were compared and analyzed in the simulation and experiment. The biological fidelity of the model was further verified. At the same time, the damage analysis showed that the adult chest compression damage criterion and the adhesive damage criterion could be used for children. Prediction of chest injury, but children's injury tolerance limits are lower than adults' tolerance limits.
Due to the lack of response data for child model validation, the current children's model and some finite element model verification used the data obtained by scaling. However, the response data obtained by scaling are not verified by the experimental data. This paper uses the finite model simulation to analyze the proportion of the model in proportion. At the same time, the effects of the young's modulus of the rib bone density on the scaling results and the effect of the pendulum mass, the diameter and the initial impact velocity on the chest response were investigated. The results were helpful to improve the accuracy of the zoom data.
Finally, the children's chest corpse experiment was carried out. A new experimental scheme for children's chest corpse was designed, and the experimental scheme was fully verified with Q6 children. On this basis, a formal child chest corpse experiment was carried out with non fresh children's corpse samples, and the chest force deformation curve of children was obtained. It will lay a foundation for further research on children's chest injury biomechanics.
The problem of children's accidental injury is becoming more and more prominent. Developing children's finite element modeling and biomechanical experiment is helpful to speed up the development of children's mathematical model and mechanical model. By using these children's models and biomechanical experiments, we can understand the damage mechanism of children and carry out the research on the protective measures on this basis. The improvement of child safety is of great practical significance.

【学位授予单位】：湖南大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：U467.14;R655

【参考文献】