利用仿真建模和有限元分析研究宏观孔隙结构与骨诱导行为的相关性

发布时间：2018-04-08 17:24

本文选题：生物陶瓷　切入点：宏观孔隙结构　出处：《西南交通大学》2017年硕士论文

【摘要】：磷酸钙生物陶瓷材料因具有良好的生物相容性而广泛应用于人工骨替代材料。研究表明,在磷酸钙陶瓷骨诱导性潜能中发挥作用的材料特性包括化学成分,宏观结构特征和微观结构特征。特别是针对磷酸钙植入材料的宏观结构与骨诱导性之间的相关性方面,尽管有大量的实验研究数据,但实验研究方法耗时长,成本高,误差大,而且缺乏对其机制系统性的理解,这限制了生物陶瓷在临床骨缺损治疗中的广泛应用。此外,大量的动物实验结果和体外培养组织工程构建体的研究都显示了微流体动力环境对支架内细胞生物功能活性具有重要影响,种种迹象表明孔隙结构很可能作为力学信号转化载体在材料骨诱导发生机制中发挥作用。故本论文基于生物力学理论,从宏观孔隙结构、体内动态环境和细胞力学刺激的相关性入手,利用对多孔支架仿真建模和有限元分析的方法,研究多孔支架的宏观结构特征与骨诱导性之间的相关性。并对多孔支架结构的优化设计提供理论依据。主要内容如下:(1)用Micro-CT的方法对制备的多孔支架进行孔隙参数分析和结构特征和趋势的提取。结果表明,多孔支架孔隙结构趋于六方密堆结构,基于此结构,利用SolidWorks软件构建了多孔支架的简化计算模型以用于后续有限元分析。根据所构建出的等效简化模型,研究了多孔支架的贯通孔/宏孔的比例极限问题。得到结论为贯通孔/宏孔的尺寸比例范围在0～0.5之间,比例下限为0,上限为0.5,当超出此上限时,支架结构出现破损缺陷。(2)用ANSYS软件构建了多孔支架的力学模型,模拟得到了多孔支架的压力位移曲线,得到理想的多孔支架的力学特性曲线是呈线性分布。并用实验测量得到的压力位移曲线数据,通过两者的对比分析,研究多孔支架的力学特性,从理论力学方面入手验证了构建的等效模型可作为实际支架的替代计算模型。(3)用F1ow simulation软件对不同宏观结构特征的多孔支架模型内的微流体动力环境进行仿真模拟,得到了不同宏观结构特征的流场分布图和内部的剪切应力数据,通过对数据的对比分析和理论研究并结合课题组前期的动物实验结果,得到结论为宏孔和贯通孔的尺寸对多孔支架材料的成骨性能有显著影响,并且这种影响是宏孔和贯通孔相互协同基于对微流体动力环境的作用后的结果。研究结论还提示材料宏观结构因素极有可能是通过微流体动力途径转化为生物功能化调控信号来影响生物陶瓷的骨诱导性。
[Abstract]:Calcium phosphate bioceramics are widely used as substitute materials for artificial bone because of their good biocompatibility.The results show that the properties of the materials that play an important role in the osteoinductive potential of calcium phosphate ceramics include chemical composition, macroscopic structure and microstructure.In particular, in view of the correlation between the macrostructure of calcium phosphate implant material and bone inductivity, although there are a lot of experimental data, the experimental research methods take a long time, high cost and large error.And the lack of systematic understanding of its mechanism limits the wide application of bioceramics in the treatment of bone defects.In addition, a large number of animal experiments and studies of tissue engineering constructions in vitro have shown that the microhydrodynamic environment has an important effect on the biological activity of cells in the scaffold.It is suggested that the pore structure may play an important role in the mechanism of bone induction as a carrier of mechanical signal transformation.Therefore, based on the biomechanical theory, this paper starts with the correlation of macro pore structure, dynamic environment in vivo and cellular mechanical stimulation, and uses the method of simulation modeling and finite element analysis of porous scaffold.To study the correlation between macrostructural characteristics and bone inductivity of porous scaffolds.It also provides the theoretical basis for the optimization design of the porous scaffold structure.The main contents are as follows: (1) the porous scaffolds were analyzed by Micro-CT method and the structure characteristics and trends were extracted.The results show that the pore structure of porous scaffold tends to be hexagonal dense stack structure. Based on this structure, a simplified calculation model of porous scaffold is constructed by using SolidWorks software for subsequent finite element analysis.Based on the equivalent simplified model, the problem of the ratio limit of the perforation hole to the macro hole of the porous scaffold is studied.It is concluded that the size ratio of the through hole to the macro hole is between 0 and 0.5, the ratio lower limit is 0 and the upper limit is 0.5. When the upper limit is exceeded, there is a damage defect in the support structure. The mechanical model of the porous support is constructed by using ANSYS software.The pressure and displacement curves of porous scaffolds were obtained by simulation, and the ideal mechanical characteristics curves of porous scaffolds were obtained with linear distribution.The mechanical properties of the porous scaffold were studied by comparing and analyzing the pressure and displacement curves measured by experiments.From the aspect of theoretical mechanics, it is verified that the constructed equivalent model can be used as a substitute calculation model for practical scaffolds. The microhydrodynamic environment in porous scaffold models with different macroscopic structural characteristics is simulated by F1ow simulation software.The distribution map of flow field and the internal shear stress data of different macroscopic structural characteristics are obtained. Through the comparative analysis and theoretical study of the data, combined with the experimental results of animal experiments in the earlier period of the research group, the flow field distribution map and the internal shear stress data are obtained.It is concluded that the size of macroporous and perforated pores has a significant effect on the osteogenic properties of porous scaffolds, and this effect is the result of the interaction between macropores and perforated pores based on the microhydrodynamic environment.The results also suggest that the macrostructure of the material may be changed into the biological functionalized regulatory signal through the microhydrodynamic pathway to influence the bone induction of bioceramics.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R318.08

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