The role of viscoelasticity of collagen fibers in articular cartilage: axial tension versus compression
The role of viscoelasticity of collagen fibers in articular cartilage: axial tension versus compression
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DOI：
10.1016/j.medengphy.2004.08.009
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发表时间：
2005-01-01
影响因子：
2.2
通讯作者：
Jurvelin, JS
中科院分区：
文献类型：
--
作者：
Li, LP;Herzog, W;Jurvelin, JS
牛关节软骨中的胶原纤维的粘弹性的作用进行了检查，在压缩和拉伸使用应力松弛测量轴向方向（垂直于关节面）。实验上，对于一个给定的轴向应变，峰值和平衡载荷都高于在拉伸比压缩，而应力松弛是更强的压缩，所示的较高的峰值平衡比。一个粘弹性纤维增强模型，包括流体流动用于分析的实验数据。胶原纤维基质被假定为具有应变依赖性拉伸模量的粘弹性，而非纤维基质被建模为线性弹性。对于轴向拉伸，胶原粘弹性被发现占大部分的应力松弛，而流体加压的拉伸应力的影响可以忽略不计。相反，对于轴向压缩，应力松弛的主要机制来自流体加压，而胶原纤维中的相关松弛主要导致径向应变的增加。有效泊松比，定义为径向和轴向应变的比率，一般是在压缩比在拉伸，并偏离真正的泊松比在拉伸试验，因为试样和加载压板之间的摩擦接触。此外，观察到轴向胶原弹性低于径向胶原弹性。本研究阐明了胶原粘弹性和间质液加压在关节软骨力学响应中的重要作用。(C)2004年IPEM。由爱思唯尔有限公司出版。保留所有权利。
The role of viscoelasticity of collagen fibers in bovine articular cartilage was examined in compression and tension using stress relaxation measurements in the axial direction (normal to the articular surface). Experimentally, for a given axial strain, both peak and equilibrium loads were higher in tension than in compression, whereas stress relaxation was stronger in compression, as indicated by the higher peak-to-equilibrium ratios. A viscoelastic fibril-reinforced model including fluid flow was used for analysis of the experimental data. The collagen fibrillar matrix was assumed to be viscoelastic with a strain-dependent tensile modulus, and the nonfibrillar matrix was modeled as linearly elastic. For axial tension, collagen viscoelasticity was found to account for most of the stress relaxation, while the effects of fluid pressurization on the tensile stress were negligible. In contrast, for axial compression, the dominant mechanism for stress relaxation arose from fluid pressurization, while the associated relaxation in collagen fibers mainly resulted in an increase in radial strain. The effective Poisson's ratio, defined as the ratio of the radial and axial strains, was generally smaller in compression than in tension, and deviated from the true Poisson's ratio in tensile tests because of the frictional contacts between the specimen and the loading platens. Furthermore, lower collagen elasticity in the axial direction was observed than in the radial direction. This study illustrates the essential role of collagen viscoelasticity and interstitial fluid pressurization in the mechanical response of articular cartilage. (C) 2004 IPEM. Published by Elsevier Ltd. All rights reserved.