关节软骨的动态力学性能研究

发布时间：2018-03-31 12:27

本文选题：猪膝关节软骨　切入点：霍普金森压杆　出处：《浙江大学》2017年硕士论文

【摘要】：膝关节为人体最大且构造最复杂的关节。人在整个生命周期中对膝关节的使用非常的频繁,其中膝关节软骨在膝关节活动中起重要作用,其主要功能为稳定膝关节,传递膝关节负荷力,缓解压力。在压力作用下,膝关节软骨被压缩,解除压力,又可伸展,类似于弹性垫的效果,可以保护软骨下的骨骼不受破坏。在强力骤然运动时,膝关节软骨发生冲撞和摩擦损伤的概率很大,膝关节软骨的动态力学性能是关系到膝关节功能是否正常运行的一个重要力学指标,对建立膝关节软骨损伤的精细化仿真模型以研究膝关节软骨损伤机理具有重要意义。与关节软骨在准静态条件下的力学性能相比,人们对其动态力学性能的研究较少,这是因为生物软组织材料在动态加载条件下的力学测试难度很大。鉴于此情况,本文在传统霍普金森压杆实验系统的基础上发展了一套能准确测试关节软骨动态力学性能的霍普金森压杆实验技术,成功获得了关节软骨的动态压缩应力-应变曲线,并发展了 ZWT本构模型,从而得到了能够准确描述关节软骨在很宽应变率范围内力学性能的非线性粘弹性本构模型。关节软骨的力学性能与其所在生理部位关系较大,而与物种关系不大。由于人体膝关节软骨获取困难,而猪膝关节软骨与人膝关节软骨在材料本构与参数属性上有相类似之处,故可用猪膝关节软骨代替人膝关节软骨对膝关节软骨的动力特性进行研究。本文选取新鲜的猪后腿膝关节处关节软骨作为研究对象,首先利用电子万能疲劳试验机对其进行了准静态压缩测试。实验结果表明关节软骨具有明显的粘弹性性质和应变率效应。本文针对膝关节软骨这种软物质在传统霍普金森压杆实验测试中存在的试样两端应力无法平衡及透射信号弱的问题,提出了相应的改进措施,并采用改进后的分离式霍普金森压杆对猪膝关节软骨进行了不同应变率下的冲击压缩实验,获得了成年猪膝关节软骨在五种应变率下即500s-1、1000s-1、2000s-1、2700s-1和3500s-1的应力-应变曲线,分析了应变率对关节软骨动态力学性能的影响。本文对不同猪龄膝关节软骨进行了生化成分测定,并根据霍普金森压杆实验技术获得了 3种不同猪龄膝关节软骨在应变率3500s-1的应力-应变曲线,探讨了不同年龄关节软骨生化成分对关节软骨动态力学性能的影响。本文以ZWT本构模型为基础,发展了一个更适合生物软组织材料的本构模型。通过对实验数据进行拟合得到了模型中的材料参数,得到了膝关节软骨ZWT本构模型,可用于描述关节软骨在准静态及高应变率下力学性能的非线性粘弹性本构模型,拟合结果与实验结果重复性好,可为以后膝关节的有限元仿真提供关节软骨的材料参数。
[Abstract]:The knee joint is the largest and most complicated joint in human body. The knee joint is used frequently in the whole life cycle, in which the articular cartilage plays an important role in the knee joint movement, and its main function is to stabilize the knee joint. Transfer knee joint load to relieve pressure. Under pressure, the cartilage of the knee joint is compressed, relieved of pressure, and can be stretched, similar to the effect of elastic pad, which can protect the bone under cartilage from destruction. The probability of collision and friction damage of articular cartilage is very high. The dynamic mechanical properties of knee cartilage is an important mechanical index related to the function of knee joint. It is of great significance to establish a fine simulation model of articular cartilage injury in order to study the mechanism of articular cartilage injury. Compared with the mechanical properties of articular cartilage under quasi-static conditions, there is less research on the dynamic mechanical properties of articular cartilage. This is because biomechanical testing of biological soft tissue materials under dynamic loading is very difficult. Based on the traditional Hopkinson compression bar experimental system, a set of experimental techniques for measuring the dynamic mechanical properties of articular cartilage have been developed in this paper. The dynamic compression stress-strain curves of articular cartilage have been obtained successfully. The ZWT constitutive model is developed and a nonlinear viscoelastic constitutive model which can accurately describe the mechanical properties of articular cartilage in a wide strain rate range is obtained. The mechanical properties of articular cartilage are closely related to its physiological position. But not related to species. Because of the difficulty of obtaining human knee cartilage, pig knee cartilage is similar to human knee cartilage in material constitutive and parameter properties. Therefore, the dynamic characteristics of knee cartilage can be replaced by porcine articular cartilage. In this paper, the fresh articular cartilage in the knee joint of the hind leg of pig is selected as the research object. Firstly, quasi-static compression test was carried out on the electronic universal fatigue testing machine. The experimental results show that articular cartilage has obvious viscoelastic properties and strain rate effect. In the experimental test of Hopkinson compression bar, the stress at both ends of the specimen can not be balanced and the transmission signal is weak. The corresponding improvement measures were put forward, and the impact compression experiments of pig knee cartilage under different strain rates were carried out by using the improved split Hopkinson pressure bar. The stress-strain curves of the articular cartilage of adult pigs were obtained under five strain rates: 500s-1 / 1000s-1 / 2000s-1 / 2000s-1N / 2700s-1 and 3500s-1, and the effect of strain rate on the dynamic mechanical properties of articular cartilage was analyzed. The biochemical composition of the articular cartilage at different ages was measured in this paper. The stress-strain curves of three kinds of porcine articular cartilage at strain rate 3500s-1 were obtained according to the Hopkinson compression bar technique. The effects of biochemical components of articular cartilage at different ages on the dynamic mechanical properties of articular cartilage were studied. A constitutive model which is more suitable for biological soft tissue materials is developed. The material parameters of the model are obtained by fitting the experimental data, and the ZWT constitutive model of knee cartilage is obtained. The nonlinear viscoelastic constitutive model can be used to describe the mechanical properties of articular cartilage under quasi-static and high strain rate. The fitting results are reproducible with the experimental results, and the material parameters of articular cartilage can be provided for the finite element simulation of knee joint.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R684;R318.01

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