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Development and validation of a novel data analysis procedure for spherical nanoindentation.

机译：球形纳米压痕的新型数据分析程序的开发和验证。

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摘要

This dissertation presents a novel approach for converting the raw load-displacement data measured in spherical nanoindentation into much more meaningful indentation stress-strain curves. This new method entails a novel definition of the indentation strain and a new procedure for establishing the effective zero point in the raw dataset---both with and without the use of the continuous stiffness measurement (CSM) data. The concepts presented here have been validated by simulations and experiments on isotropic metallic samples of aluminum and tungsten. It is demonstrated that these new indentation stress-strain curves accurately capture the loading and unloading elastic moduli, the indentation yield points, as well as the post-yield characteristics in the tested samples.;Subsequently this approach has been applied on a wide range of material systems including metals, carbon nanotubes (CNTs), ceramics and bone. In metals, these data analysis techniques have been highly successful in explaining several of the surface preparation artifacts typically encountered during nanoindentation measurements. This approach has also been extended to anisotropic polycrystalline samples, where a judicious combination of Orientation Imaging Microscopy (OIM) and nanoindentation were used to estimate, for the first time, the changes in slip resistance in deformed grains of Fe-3%Si steel.;Similar studies on dense CNT brushes, with ∼10 times higher density than CNT brushes produced by other methods, demonstrate the higher modulus (∼17-20 GPa) and orders of magnitude higher resistance to buckling in these brushes than vapor phase deposited CNT brushes or carbon walls, showing their promise for energy-absorbing coatings. Even for a complex hierarchical material system like bone, these techniques have elucidated trends in the elastic and yield behavior at the lamellar level in the femora (thigh bone) of different inbred mouse strains. Thus bone with a higher mineral-to-matrix ratio demonstrated a trend towards a higher modulus and yield strength. A similar trend was also observed during indentation testing of 'wet' or hydrated bone (which represents more closely bone's naturally hydrated in-vivo environment), where bone with a higher collagen content or a lower mineral-to-matrix ratio tends towards a higher viscoelastic response.
机译：本文提出了一种新颖的方法，可以将球形纳米压痕中测得的原始载荷-位移数据转换为更有意义的压痕应力-应变曲线。这种新方法需要压痕应变的新颖定义和在原始数据集中建立有效零点的新程序-无论是否使用连续刚度测量（CSM）数据。此处介绍的概念已通过对铝和钨的各向同性金属样品进行的模拟和实验得到验证。结果表明，这些新的压痕应力-应变曲线可以准确地捕获被测样品的加载和卸载弹性模量，压痕屈服点以及屈服后特性。材料系统，包括金属，碳纳米管（CNT），陶瓷和骨骼。在金属中，这些数据分析技术在解释纳米压痕测量过程中通常遇到的几种表面处理伪影方面非常成功。这种方法也已扩展到各向异性多晶样品，其中取向成像显微镜（OIM）和纳米压痕的明智组合首次被用于估计Fe-3％Si钢变形晶粒的抗滑性变化。 ；对稠密CNT刷的类似研究，其密度是其他方法生产的CNT刷的约10倍，证明了与气相沉积CNT刷相比，这些刷具有更高的模量（〜17-20 GPa）和更高的耐屈曲性或碳墙，表明它们有望吸收能量。即使对于像骨骼这样的复杂的分层材料系统，这些技术也阐明了不同自交小鼠品系的股骨（大腿骨）在板层水平的弹性和屈服行为的趋势。因此，具有较高的矿物质与基质比率的骨表现出朝向更高的模量和屈服强度的趋势。在“湿”或水合骨骼的压痕测试中也观察到了类似的趋势（这更代表了骨骼的自然水合体内环境），其中胶原蛋白含量较高或矿物质与基质比例较低的骨骼趋向于较高粘弹性反应。

著录项

  • 作者

    Pathak, Siddhartha.;

  • 作者单位

    Drexel University.;

  • 授予单位 Drexel University.;
  • 学科 Engineering Biomedical.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 194 p.
  • 总页数 194
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物医学工程;工程材料学;
  • 关键词

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