缺损关节软骨损伤演化力学机制的数值研究

发布时间：2018-02-07 09:10

本文关键词： 微缺损软骨力学机制损伤演化数值模拟多种载荷　出处：《天津理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：膝关节是人体中最大且非常重要的关节,由于它具有使用频繁、运动量大、承受应力高的特点,很容易遭到不同程度的损伤,其关节表面软骨的损伤在临床上就比较常见。而由于关节软骨的特殊性,加之本身再生能力较差,对其修复治疗十分困难,其原因之一便是软骨的损伤演化机制本身就非常复杂。因此,深入研究软骨的损伤病理和损伤演变机制就显得尤为重要。由于体内软骨缺损处力学环境不易测量,同时考虑到软骨损伤后的复杂性,本文在实验的基础上,主要通过有限元方法研究了微缺损软骨的损伤演化过程,获得了软骨在多种载荷条件下的损伤演化规律和损伤力学机制,为关节软骨的临床疾病研究和修复治疗提供了理论依据。本文研究过程包含数值仿真研究和实验研究。实验研究中,利用课题组专门设计的加载装置对猪膝关节软骨试样进行了多种载荷加载实验,并借助数字图像散斑技术采集分析实验图片,将处理的实验结果与仿真结果进行对比分析,发现两者变化趋势较为相近,结果吻合良好,从而验证了模型的有效性。数值仿真研究是本文的核心内容,主要通过有限元软件ANSYS12.0建立了多种载荷下微损伤软骨的纤维增强二维模型来研究关节软骨的损伤演化力学机制,模型中的纤维首次采用了更接近实际的拱形交叉结构。以多个模型为基础,分别研究了在多种载荷下微缺损软骨的损伤力学机制,主要包括:根据计算的数据结果和损伤准则,分析对比了在滚压、滑压和均布压缩加载下的微缺损软骨的损伤演化过程,探索了损伤扩展方向和速率的变化规律以及不同滚动/滑动速度和不同压缩量对损伤扩展的影响,另外还分析了纤维单向破坏对软骨承载的影响及内部裂纹对软骨应力分布的影响。数值研究表明软骨的损伤有着比普通复合材料更为复杂的扩展演化过程,是载荷形式、载荷大小及运动速度等多种因素共同作用的结果。软骨损伤演化过程与纤维的分布有着密切的关系,在损伤扩展前期,软骨中的裂纹和损伤优先沿着纤维切线方向延伸,纤维在损伤中起到了导向作用,完整精细的纤维网络对软骨的承载起着重要作用,纤维一旦断裂将加速软骨基质的损伤。相比于滑压载荷,滚压载荷对软骨损伤演化的影响更大,在软骨损伤演化过程中,其扩展方向和扩展速度随着损伤程度不断发生变化,在均布压缩下,软骨还同时存在向深层和两侧扩展的趋势。软骨的损伤与载荷压缩量呈明显的正相关性,运动速度对软骨基质有更大的影响。内部细小裂纹在长期受载下会逐渐延伸扩展,可能形成表面可见的损伤。损伤会造成软骨机能的退变,导致承载能力显著下降,所以软骨损伤需要得到及时修复。
[Abstract]:The knee joint is the largest and very important joint in the human body. Because of its characteristics of frequent use, large amount of exercise and high stress, the knee joint is vulnerable to various degrees of injury. The injury of articular surface cartilage is quite common in clinic. However, because of the particularity of articular cartilage and its poor regeneration ability, it is very difficult to repair and treat it. One of the reasons is that the mechanism of cartilage damage evolution is very complicated. Therefore, it is very important to study the damage pathology and damage evolution mechanism of cartilage, because it is difficult to measure the mechanical environment of cartilage defect in vivo. At the same time, considering the complexity of cartilage injury, based on the experiment, the damage evolution process of microdefect cartilage is studied by finite element method. The damage evolution law and damage mechanics mechanism of cartilage under various loads are obtained. It provides a theoretical basis for the clinical study and repair treatment of articular cartilage. The research process in this paper includes numerical simulation and experimental research. Using the loading device specially designed by the research group, a variety of loading experiments were carried out on the cartilage samples of the knee joint of pigs, and the digital image speckle technique was used to collect and analyze the experimental pictures, and the experimental results were compared with the simulation results. It is found that the variation trend of the two models is similar and the results are in good agreement, which verifies the validity of the model. Numerical simulation is the core content of this paper. In order to study the mechanism of damage evolution of articular cartilage, the fiber reinforced two-dimensional model of micro-damaged cartilage under various loads was established by finite element software ANSYS12.0. For the first time, the fiber in the model adopts a more practical arch cross structure. Based on several models, the damage mechanics mechanism of microdefect cartilage under various loads is studied separately, including: according to the calculated data and damage criterion, The damage evolution process of microdefect cartilage under rolling, sliding and uniform compression is analyzed and compared. The variation of damage propagation direction and rate and the effects of different rolling / sliding velocity and different compression amount on damage propagation are explored. In addition, the effects of unidirectional fiber failure on cartilage loading and the influence of internal cracks on cartilage stress distribution are analyzed. Numerical results show that cartilage damage has a more complex propagation and evolution process than ordinary composite materials, and is a form of load. The evolution of cartilage damage is closely related to the distribution of fibers. In the early stage of damage expansion, cracks and injuries in cartilage preferentially extend along the tangent direction of the fibers. Fiber plays a guiding role in the damage. The complete and fine fiber network plays an important role in the loading of cartilage. Once the fiber breaks, it will accelerate the damage of cartilage matrix. The influence of rolling load on cartilage damage evolution is greater. In the process of cartilage damage evolution, the direction and speed of cartilage expansion change with the damage degree, and under uniform compression, There is also a tendency of cartilage spreading to the deep and both sides. The damage of cartilage is positively correlated with the amount of load compression, and the velocity of movement has a greater effect on the cartilage matrix. The damage may result in degeneration of cartilage function and decrease of load-carrying capacity, so cartilage damage needs to be repaired in time.
【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R68;R318.01

【相似文献】