Increasing strain and strain rate strengthen transient stiffness but weaken the response to subsequent compression for articular cartilage in unconfined compression
Increasing strain and strain rate strengthen transient stiffness but weaken the response to subsequent compression for articular cartilage in unconfined compression
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DOI：
10.1016/s0021-9290(03)00006-x
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发表时间：
2003-06-01
影响因子：
2.4
通讯作者：
Buschmann, MD
中科院分区：
文献类型：
--
作者：
Langelier, E;Buschmann, MD
研究了全厚牛关节软骨在无侧限压缩条件下的应变幅值和应变率相关的非线性行为和载荷诱导的力学性能变化。在应变率从0.053%/S到5.8%/S的范围内，进行了一系列有限变形(从0.9%到34.5%名义应变)的压缩试验，分析了峰值和平衡载荷，以确定线性和非线性响应的应变幅值和应变率相关性。试验方案旨在通过在试验坡道之间散布类似于1.1%变形和类似于0.44%/S应变率的小幅度见证坡道来揭示由于这些有限变形引起的力学性能的变化(“见证”意为评估任何力学性能变化)。我们发现，峰值载荷表现出高度的非线性，随着压缩幅度的增加而变硬，随着应变率的增加而变得更强。对见证斜坡的响应表明，当压缩幅度达到1.9-2.9%应变或更高时，力学弱化发生，且在较高应变率时，机械弱化更为明显。这些发现描绘了软骨的线性和非线性行为的区域，并指出了可能导致力学性质改变的载荷类型。这项研究的生物学意义是，依赖于应变幅度和应变率的僵化可能是承受生理负荷和保护细胞和基质免受机械损伤所必需的。小幅压缩时机械强度减弱所反映的结构变化也可能引发重塑或疾病过程。(C)2003爱思唯尔科学有限公司。保留所有权利。
Strain amplitude and strain rate dependent nonlinear behavior and load-induced mechanical property alterations of full-thickness bovine articular cartilage attached to bone were investigated in unconfined compression. A sequence of test compressions of finite deformation (ranging from 0.9% to 34.5% nominal strain) was performed at strain rates ranging from similar to0.053%/s to 5.8%/s. Peak and equilibrium loads were analyzed to determine strain amplitude and strain rate dependence of linear versus nonlinear responses. The test protocol was designed to reveal changes in mechanical properties due to these finite deformations by interspersing small-amplitude witness ramps of similar to1.1% deformation and similar to0.44%/s strain rate between the test ramps ("witness" meaning to assess any mechanical property changes). We found that peak loads displayed high nonlinearity, stiffening with both increasing compression amplitude and more so with increasing strain rate. The response to witness ramps suggested that mechanical weakening occurred when compression amplitude reached 1.9-2.9% strain and beyond, and that weakening was much more significant at higher strain rate. These findings delineate regimes of linear versus nonlinear behavior of cartilage, and indicate the types of loads which can cause mechanical property alterations. Biological implications of this study are that strain amplitude and strain rate dependent stiffening may be essential to bear physiological loads and to protect cells and matrix from mechanical damage. Structural changes reflected by mechanical weakening at small compression could also initiate remodeling or disease processes. (C) 2003 Elsevier Science Ltd. All rights reserved.