幼年和成年关节软骨的准静态力学性能和棘轮性能研究

发布时间：2018-03-19 03:02

本文选题：关节软骨　切入点：幼年和成年　出处：《天津理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：骨关节炎是一种退行性疾病,主要表现为进行性破坏的关节软骨,软骨下骨增厚,骨赘形成和滑膜炎症,尽管是所有因素的联合影响,关节软骨破坏被认为是骨关节炎发病机制的主要中介。关节软骨覆盖在膝盖关节的末端,支持和分配关节表面的负载和压力,在运动中起到减缓震动的作用。关节软骨的成熟是后天发展的过程,用以适应关节表面特定位置生物力学的需求,一般软骨在生长和发育过程中形态上发生变化进一步达到成熟,同时机械疲劳是生长过程中造成骨关节炎的主要原因。因此,研究成年和幼年关节软骨的动态和静态机械性能对关节软骨疾病的预测和治疗有重要作用,并能够为人工软骨的制造提供依据。本文采用一个月和八个月猪的新鲜关节软骨制备了幼年组和成年组的实验模型,测试了它们在准静态压缩载荷下的蠕变、率相关性能以及动态压缩下的棘轮行为。同时,借助非接触式数字图像技术研究了幼年和成年猪关节软骨不同层区的力学行为。实验研究发现,随着施加应力的增加,幼年组软骨和成年组软骨蠕变应变的累积速率明显增快,并且幼年组软骨的蠕变速率明显大于成年组软骨蠕变速率,二者之间的差距随着施加应力的增加而增加;幼年组软骨各个层区的蠕变应变和蠕变速率均高于成年组软骨蠕变应变和蠕变速率,在浅表层二者之间的差距最大,中间层弱之,在深层区二者的差距并不明显,并且随着应力增大这种现象更加明显;成年软骨和幼年软骨有着各自的率相关性,加载过程中成年组软骨的弹性模量高于幼年组软骨的弹性模量。比较幼年组软骨和成年组软骨的棘轮行为发现,相同圈数、应力幅值和加载率下,幼年组软骨的高于成年组软骨的棘轮应变,循环加载初期二者差异比较明显,并且应力幅值的改变对成年软骨和幼年软骨棘轮行为的差异影响很大。通过完成蠕变、蠕变-恢复和保持时间对循环加载影响的实验,研究了静态与动态载荷结合下关节软骨的力学行为。结果发现,蠕变越久,应变越大,在一定时间恢复之后仍然存在不可逆的变形;幅值越大关节软骨棘轮应变积累越迅速;随波峰和波谷保持时间的增加,关节软骨棘轮应变速率加快;蠕变预加载使软骨强化,有效地改善了关节软骨抵抗棘轮变形的能力,蠕变后恢复会减弱这种强化作用。
[Abstract]:Osteoarthritis is a degenerative disease characterized by progressive destruction of articular cartilage, thickening of subchondral bone, osteophyte formation and synovitis, although it is a combination of all factors. Articular cartilage destruction is thought to be the main mediator of the pathogenesis of osteoarthritis. Articular cartilage covers the end of the knee joint and supports and distributes the load and pressure on the surface of the joint. The maturation of articular cartilage is a process of acquired development to meet the requirements of biomechanics at specific positions on the surface of the joint. During the growth and development of cartilage, the morphological changes have further matured, and mechanical fatigue is the main cause of osteoarthritis during growth. The study of the dynamic and static mechanical properties of adult and juvenile articular cartilage plays an important role in the prediction and treatment of articular cartilage diseases. The experimental models of juvenile and adult groups were prepared by using the fresh articular cartilage of one and eight months-old pigs, and their creep under quasi-static compression load was tested. Rate-dependent properties and ratchet behavior under dynamic compression. At the same time, the mechanical behavior of different layers of articular cartilage in young and adult pigs was studied by means of contactless digital image technique. The creep strain accumulation rate of cartilage in juvenile group and adult group increased obviously, and the creep rate of cartilage in juvenile group was higher than that in adult group, and the gap between them increased with the increase of applied stress. The creep strain and creep rate of each layer of cartilage in juvenile group were higher than that in adult group. The difference between them was the biggest in shallow surface layer, the weak in middle layer, and the difference was not obvious in deep layer. And with the increase of stress, the phenomenon is more obvious; the adult cartilage and juvenile cartilage have their own rate correlation, The elastic modulus of cartilage in adult group was higher than that in young group during loading. The ratchet behavior of cartilage in juvenile group and adult group was compared. The ratchet strain of juvenile cartilage is higher than that of adult cartilage, the difference between them is obvious at the beginning of cyclic loading, and the change of stress amplitude has great influence on the ratchet behavior of adult cartilage and juvenile cartilage. The effect of creep-recovery time and retention time on cyclic loading is studied. The mechanical behavior of articular cartilage under static and dynamic loading is studied. The results show that the longer the creep is, the greater the strain is. There is still irreversible deformation after a certain time recovery; the larger the amplitude, the faster the strain accumulation of articular cartilage ratchet; with the increase of wave peak and trough holding time, the strain rate of articular cartilage ratchet is accelerated, and the cartilage is strengthened by creep preloading. The ability of articular cartilage to resist ratchet deformation is improved effectively.
【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】：R684.3;R318.1

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