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兒童胸部有限元模型開發(fā)及損傷機(jī)理研究

發(fā)布時(shí)間:2018-04-27 16:49

  本文選題:兒童安全 + 損傷生物力學(xué); 參考:《湖南大學(xué)》2013年博士論文


【摘要】:在兒童意外傷害的研究中發(fā)現(xiàn),兒童胸部遭受損傷時(shí),容易形成嚴(yán)重?fù)p傷并伴有較高的死亡率。人體胸腔內(nèi)保護(hù)著維持人體生命機(jī)能的呼吸和血液循環(huán)系統(tǒng)以及包括肝在內(nèi)的一些其他重要腹部器官,因此,當(dāng)兒童乘車時(shí),需要對(duì)其胸部給予充分的保護(hù)。由于兒童與成人在解剖結(jié)構(gòu)和材料特性上的差異,使得成人的胸部損傷準(zhǔn)則和容忍極限并不適用于兒童;谶@些損傷準(zhǔn)則和容忍極限開發(fā)出的成人約束系統(tǒng)也可能無法很好地保護(hù)兒童,甚至反而給兒童造成致命的傷害。因此,研究?jī)和夭繐p傷準(zhǔn)則、容忍極限及防護(hù)方法具有重要的現(xiàn)實(shí)意義。生物力學(xué)實(shí)驗(yàn)和計(jì)算機(jī)仿真模擬是研究人體損傷機(jī)理和容忍極限的常用方法。因此,本文在大量文獻(xiàn)研究的基礎(chǔ)上,開展了兒童胸部有限元建模及兒童胸部生物力學(xué)實(shí)驗(yàn)研究,并利用有限元分析方法對(duì)兒童胸部損傷機(jī)理、損傷準(zhǔn)則和容忍極限及兒童胸部縮放響應(yīng)數(shù)據(jù)進(jìn)行了研究。 由于缺少相應(yīng)的兒童建模數(shù)據(jù),,包括幾何數(shù)據(jù)、材料數(shù)據(jù)以及驗(yàn)證數(shù)據(jù),導(dǎo)致可用于兒童安全研究的詳細(xì)兒童胸部模型十分缺乏。本文通過收集多個(gè)臨床治療中獲得的兒童患者CT (Electronic Computer X-ray Tomography Technique)和MRI(Magnetic Resonance Imaging)圖像,結(jié)合Hypermesh (10.0, Altair, Tory, MI)軟件將多名患者的數(shù)據(jù)整合成標(biāo)準(zhǔn)的10歲兒童幾何模型。利用ANSYS ICEM (ANSYS,Canonsburg, Pennsylvania, U.S.A)的Block-Controlled對(duì)骨骼和內(nèi)臟進(jìn)行了純六面體網(wǎng)格劃分。模型具有詳細(xì)的兒童解剖學(xué)結(jié)構(gòu),包括皮膚、肋骨、肋軟骨、心臟、肺、大血管、膈膜及腹部器官等等。各組織的的材料特性則基于國(guó)內(nèi)外文獻(xiàn)中成人模型的材料參數(shù),利用比例縮放的方法獲得。 精確的兒童胸部力-變形響應(yīng)數(shù)據(jù)是開發(fā)兒童有限元模型及兒童假人模型的關(guān)鍵數(shù)據(jù)之一。然而,由于倫理道德的限制,很難大量開展傳統(tǒng)的尸體實(shí)驗(yàn)來獲得兒童響應(yīng)數(shù)據(jù)。本文再次利用臨床治療過程中獲取的兒童CPR胸部響應(yīng)數(shù)據(jù)對(duì)建立的有限元模型進(jìn)行了靜態(tài)驗(yàn)證、材料的參數(shù)化研究及邊界加載條件的影響研究,這些研究有助于提高模型的生物逼真度,獲得精確的兒童材料參數(shù),為今后臨床CPR獲得更為精確的人體胸部響應(yīng)數(shù)據(jù)提供指導(dǎo)。此外,結(jié)合兒童在臨床CPR中加載和損傷情況,利用模型開展靜態(tài)加載下的損傷分析,研究結(jié)果有利于提高模型在靜態(tài)加載下的損傷預(yù)測(cè)能力。 CPR中的加載屬于靜態(tài)加載的范疇,若要將建立的兒童有限元模型用于汽車安全等高速?zèng)_擊條件下的損傷研究,還需對(duì)模型進(jìn)行動(dòng)態(tài)響應(yīng)的驗(yàn)證;谀壳皣(guó)內(nèi)外少量的與兒童胸部相關(guān)的尸體實(shí)驗(yàn)數(shù)據(jù),對(duì)模型在撞擊及斜拉式安全帶加載下的動(dòng)態(tài)響應(yīng)進(jìn)行了仿真分析。主要對(duì)比分析了仿真和實(shí)驗(yàn)中獲得的胸部的力-變形響應(yīng)及肋骨、內(nèi)臟等的損傷情況,進(jìn)一步驗(yàn)證了模型的生物逼真度。同時(shí),損傷分析的結(jié)果表明成人胸部壓縮量損傷準(zhǔn)則和黏性損傷準(zhǔn)則可用于兒童胸部損傷的預(yù)測(cè),但兒童的損傷容忍極限值均要低于成人的容忍極限值。 由于缺乏用于兒童模型驗(yàn)證的響應(yīng)數(shù)據(jù),目前的兒童假人模型及部分有限元模型驗(yàn)證工作中采用了比例縮放獲得的數(shù)據(jù)。然而比例縮放獲得的響應(yīng)數(shù)據(jù)本身沒有經(jīng)過實(shí)驗(yàn)數(shù)據(jù)的驗(yàn)證,本文利用開發(fā)的有限模型仿真分析了模型在比例縮放條件下的響應(yīng)情況,對(duì)比了模型胸部響應(yīng)結(jié)果與縮放獲得的胸部通道數(shù)據(jù)。同時(shí),研究了肋骨骨密質(zhì)楊氏模量對(duì)縮放結(jié)果的影響及擺錘質(zhì)量、直徑和初始撞擊速度對(duì)胸部響應(yīng)的影響。研究結(jié)果有利于提高縮放數(shù)據(jù)的準(zhǔn)確性。 最后,開展了兒童胸部尸體實(shí)驗(yàn)。設(shè)計(jì)了一種新的兒童胸部尸體實(shí)驗(yàn)方案,并利用Q6兒童假人對(duì)該實(shí)驗(yàn)方案進(jìn)行了充分的驗(yàn)證。在此基礎(chǔ)上,利用非新鮮的兒童尸體樣本,開展了正式的兒童胸部尸體實(shí)驗(yàn),獲得了兒童胸部力-變形曲線。為今后進(jìn)一步開展兒童胸部損傷生物力學(xué)研究奠定了基礎(chǔ)。 當(dāng)今兒童意外傷害問題逐漸突出,開展兒童有限元建模和生物力學(xué)實(shí)驗(yàn)研究,有利于加快兒童數(shù)學(xué)模型及機(jī)械模型的發(fā)展,從而可通過利用這些兒童模型及生物力學(xué)實(shí)驗(yàn)了解兒童損傷機(jī)理并在此基礎(chǔ)上開展損傷防護(hù)措施的研究,對(duì)兒童安全的提高具有重大的現(xiàn)實(shí)意義。
[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.

【學(xué)位授予單位】:湖南大學(xué)
【學(xué)位級(jí)別】:博士
【學(xué)位授予年份】:2013
【分類號(hào)】:U467.14;R655

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