Influences of spherical tip radius, contact depth, and contact area on nanoindentation properties of bone
Influences of spherical tip radius, contact depth, and contact area on nanoindentation properties of bone
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DOI：
10.1016/j.jbiomech.2010.10.008
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发表时间：
2011-01-11
影响因子：
2.4
通讯作者：
Ferguson, Virginia L.
中科院分区：
文献类型：
--
作者：
Paietta, Rachel C.;Campbell, Sara E.;Ferguson, Virginia L.
纳米压痕作为一种测量骨的微观力学性能和预测其宏观性能的手段已被广泛应用。使用R=5、25、65和200微米的一系列球形压痕尖端，通过实验探索了压痕深度和压痕尖端几何形状在测量骨组织分级特性中的作用。纳米压痕阵列不针对特定的结构或位置，能够在单个样本上对PMMA嵌入的牛、皮质骨中的骨离子进行统计采样，以获得最大位移范围(最小100 Tun和最大2000 nm)。然后利用弹性有限元模型分离压头尖端半径、接触面积和片层结构内位置的贡献，并与实验结果进行比较。对于R=5µm的小压头，压痕模数随着接触深度和塑性变形的增加而一致地增加，从而导致弹性性能的人为增加。虽然较大的半径尖端(R=25、65和200微米)无法评估表面的高空间分辨率，但它们产生的数据代表了较小尖端的较低载荷和接触深度测量。然而，随着压头尖端尺寸的增加，材料对二维表面力学性能变化的敏感性消失。相应地，测量方差也减小，因为对压痕响应起作用的体积代表了表面粗糙度、变化的矿物质含量、缺陷以及潜在的组织类型和结构的平均值。(C)2010爱思唯尔有限公司。保留所有权利。
Nanoindentation has been widely used as a means to measure the micro-mechanical properties of bone and to predict the macroscopic properties. The role of indent depth and indenter tip geometry in measuring the hierarchical properties of bone tissue was explored experimentally using a range of spherical indenter tips of R= 5,25,65, and 200 mu m. Nanoindentation arrays, not targeted to fall on specific structures or locations, enabled statistical sampling of osteons within PMMA-embedded, bovine, cortical bone on a single sample to a range of maximum displacements (minimum of 100 Tun and maximum of 2000 nm). Elastic finite element models were then utilized to isolate the contributions of indenter tip radius, contact area, and position within the lamellar structure in comparison to the experimental results. For a small, R=5 mu m indenter tip, indentation modulus consistently increased with contact depth and increased plastic deformation, resulting in an artificial increase in elastic properties. While larger radius tips (R=25, 65, and 200 mu m) did not enable evaluation of a high spatial resolution on the surface, they produced data that was representative of the lower load and contact depth measurements with the smaller tip. However the sensitivity to mechanical property variations across the 2-D surface of the material was lost with increase in indenter tip size. Correspondingly, measurement variance was also decreased as the volume contributing to the indent response represented an average of surface roughness, varying mineral content, defects, and underlying tissue type and structure. (C) 2010 Elsevier Ltd. All rights reserved.