Experimental validation of a flat punch indentation methodology calibrated against unconfined compression tests for determination of soft tissue biomechanics
Experimental validation of a flat punch indentation methodology calibrated against unconfined compression tests for determination of soft tissue biomechanics
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DOI：
10.1016/j.jmbbm.2016.02.019
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发表时间：
2016-07-01
影响因子：
3.9
通讯作者：
Knight, M. M.
中科院分区：
文献类型：
--
作者：
Delaine-Smith, R. M.;Burney, S.;Knight, M. M.
由于样本几何不规则性、切割完整且适当尺寸的测试样本的困难以及夹具滑动或损坏的问题，使用标准压缩或拉伸测试对软生物组织进行机械表征提出了重大挑战。压痕可以克服这些问题，但需要将模型与生成的载荷位移数据进行拟合，以便计算模量。尽管该技术得到广泛使用，但很少有研究通过实验验证其选择的模型或补偿边界效应。在这项研究中，使用不同浓度和尺寸的粘弹性水凝胶来校准在大样本应变变形（20%）下执行的压痕技术，并使用一系列常规使用的数学模型进行分析。将刚性、平端圆柱形压头应用于每个样品，计算“压痕模量”和松弛特性，并与无侧限压缩获得的值进行比较。只有一个压痕模型显示出良好的一致性（= 1:1，并且样品直径与压头直径比 >= 4:1 是获得最大精度所必需的。然而，并不总是可以在这些限制内使用生物样品，因此我们开发了一系列校正因子。该方法使用人类患病网膜和牛关节软骨进行了验证，导致机械性能与压缩值紧密匹配。因此，我们提出了一种广泛使用的压痕分析方法，可以更准确地计算材料力学，这在材料力学的研究中非常重要软组织发育、衰老、健康和疾病 (C) 2016 作者由 Elsevier Ltd 出版。
Mechanical characterisation of soft biological tissues using standard compression or tensile testing presents a significant challenge due to specimen geometrical irregularities, difficulties in cutting intact and appropriately sized test samples, and issues with slippage or damage at the grips. Indentation can overcome these problems but requires fitting a model to the resulting load-displacement data in order to calculate moduli. Despite the widespread use of this technique, few studies experimentally validate their chosen model or compensate for boundary effects. In this study, viscoelastic hydrogels of different concentrations and dimensions were used to calibrate an indentation technique performed at large specimen-strain deformation (20%) and analysed with a range of routinely used mathematical models. A rigid, flat-ended cylindrical indenter was applied to each specimen from which 'indentation moduli' and relaxation properties were calculated and compared against values obtained from unconfined compression. Only one indentation model showed good agreement (= 1:1 and sample diameter to indenter diameter ratio >= 4:1 was necessary to achieve the greatest accuracy. However, it is not always possible to use biological samples within these limits, therefore we developed a series of correction factors. The approach was validated using human diseased omentum and bovine articular cartilage resulting in mechanical properties closely matching compression values. We therefore present a widely useable indentation analysis method to allow more accurate calculation of material mechanics which is important in the study of soft tissue development, ageing, health and disease. (C) 2016 The Authors. Published by Elsevier Ltd.