Sucker Rings from the Humboldt Squid Dosidicus gigas: The Role of Nanotubule Architecture on the Mechanical Properties
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The application of the AFM nanoindentation procedure in order to determine the Young's modulus values of specific nanoregions, results in many uncertainties, especially when biological samples are tested. This fact is due mainly to significant errors concerning the Young's modulus calculation because physical parameters such as the spring constant of the cantilever and the exact shape and size of the tip provide uncertainties. Thus, the objective of this paper was to introduce a more accurate and simple approach of the nanoindentation technique by introducing the relative differences of Young's modulus values. The new approach can be applied in measurements where the influence of a controlled external factor on a specific nanoregion is tested or variations in the mechanical properties of heterogeneous materials are investigated. The analysis was based on the general mathematical analysis which is used in the indentation procedure for the characterization of biological samples. The major advantage of the new technique is that it depends only on the cantilever's deflection – displacement curves which can be obtained with great accuracy. In addition, in order to provide full insight in the new technique, the mechanical heterogeneity of collagen was examined. As a conclusion, when a sample is tested under the influence of a controlled external factor, or when inhomogeneous samples are tested, the determination of the percentage variations of the Young's modulus is the most accurate parameter. Keywords: AFM, biomaterials, cantilever's spring constant, mechanical nano-characterization, nanoindentation, percentage differences of Young's modulus, Young's modulus.
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Instrumented nanoindentation (NI) was used to examine the viscoelastic properties of poly(methyl methacrylate) (PMMA) as an amorphous polymer model. An evaluation combining adhesive contact and empiric spring–dashpot models has been applied to obtain the instantaneous elastic modulus E0 and the infinitely elastic modulus E∞ from nanoindentation creep curves. The value of E0 has been compared to moduli obtained with atomic force microscopy-based nanoindentation (AFM-NI) and compression tests. Furthermore, the elastic modulus has been evaluated by the method introduced by Oliver and Pharr (O&P) for the NI and AFM-NI results. Comparison of the elastic modulus E0 from the creep measurements of NI and AFM-NI to compression tests reveals good agreement of the results. However, only the O&P based AFM-NI results yield to lower values.
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Middle lamella
Lamella (surface anatomy)
Micromechanics
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Many biological materials are known to be anisotropic. In particular, microstructural components of biological materials may grow in a preferred direction, giving rise to anisotropy in the microstructure. Nanoindentation has been shown to be an effective technique for determining the mechanical properties of microstructures as small as a few microns. However, the effects of anisotropy on the properties measured by nanoindentation have not been fully addressed. This study presents a method to account for the effects of anisotropy on elastic properties measured by nanoindentation. This method is used to correlate elastic properties determined from earlier nanoindentation experiments and from earlier ultrasonic velocity measurements in human tibial cortical bone. Also presented is a procedure to determine anisotropic elastic moduli from indentation measurements in multiple directions. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res 57: 108–112, 2001
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ABSTRACT Acquiring the micromechanical property of phases in tight sandstones by conventional mechanical testing is a big challenge because of the heterogeneity and complexity of mineralogical composition in sandstone systems. In this study, nanoindentation and AFM (atomic force microscope) technologies were employed to figure out the mechanical characteristic of tight sandstones. Nanoindentation results show that the average Young modulus of quartz is 72.78 GPa in tight sandstones. We found that nanoindentation needs more methods like SEM and EDS to separate the modulus of phases in tight sandstone. In contrast, AFM can easily recognize the elastic modulus of various phases with high accuracy and distinction. AFM results show that the Young modulus of quartz is 7.4 GPa and the Young modulus of minerals is 2.28 GPa. Moreover, the modulus value in nanoindentation is higher than that in AFM. The difference in modulus results of quartz by AFM and nanoindentation is due to the selection in probe in AFM. Overall, it shows that AFM is more suitable for achieving the goal of identifying the modulus of various phases in tight sandstones. The knowledge obtained from this paper is promising in the application of nanoindentation and AFM in tight sandstones. It will also benefit the study of micromechanical characteristics of various phases in tight sandstones. INTRODUCTION Acquiring the mechanical property is beneficial for several engineering aspects. Such as designing hydraulic fracturing schemes, enhancing oil recovery, and keeping wellhole stability(Li et al., 2019; Shen et al., 2022; Q. Wang et al., 2022). Rock consisting of several minerals is widely accepted as a homogenous and complex material. In the conventional mechanical tests, the obtained results represent the overall mechanical characterization of rock, which is regarded as the identical mechanical property of minerals (Brotóns et al., 2013). Uniaxial and triaxial pressure tests are typically applied to characterize the mechanical property of rock(Palchik, 2011; J. Wang et al., 2021). However, from the micro-scale, there are different pore structures and components of the minerals in the rock. The result is that the micromechanical characterizations between several minerals differ a lot(Liu et al., 2021; Wu et al., 2020). Therefore, acquiring the micromechanical property of phases in rocks by conventional mechanical testing is a big challenge because of the heterogeneity and complexity of mineralogical composition in rock systems(T. Wang et al., 2022). That is to say, by obtaining the micro-mechanical properties of phases of minerals in the rock, we can have an explicit knowledge of the mechanical property of rock.
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This paper carries out a preliminary study for the elastic properties of single walled carbon nanotube (SWCNT) thin film. The SWCNT thin films (~250 nm) are prepared by a simple and cost effective method of spin-coating technology. Nanoindentation test with a Berkovich indenter is used to determine the hardness and elastic modulus of the SWCNT thin film. It is important to note that the elastic properties of SWCNT film are indirectly derived from the information of load and displacement of the indenter under certain assumptions, deviation of the 'test value' is inevitable. In this regard, uncertainty analysis is an effective process in guarantying the validity of the material properties. This paper carries out uncertainty estimation for the tested elastic properties of SWCNT film by nanoindentation. Experimental results and uncertainty analysis indicates that nanoindentation test could be an effective and reliable method in determine the elastic properties of SWCNT thin film. Moreover, the obtained values of hardness and elastic modulus can further benefit the design of SWCNT thin film based components.
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The elastic energy storing capability of bulk metallic glasses was evaluated by employing depth-sensing nanoindentation. The elastic energy densities of four glassy alloys, determined by nanoindentation measurements, are fairly close to their theoretical values estimated from elastic modulus and theoretical strength. This study provides an accurate and quick method to measure the elastic properties of bulk metallic glasses.
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Fibrils were isolated from rat tail tendons and the nanoindentation tests and tensile tests of these fibrils were performed in air (dry condition). In the nanoindentation test using atomic force microscope (AFM), the indentation depth and force of the AFM tip were determined by the force curve measurement. Elastic modulus was calculated from these data using Hertzian contact theory. In the tensile test, the both ends of the fibril were wound on to the tips of microneedles and the fibril was stretched to failure by moving the microneedle under dark-field observation. Elastic modulus was determined as the slope of the approximate line of the measured stress-strain relation. Elastic moduli measured by the nanoindentation tests and tensile tests were 0.97 ± 0.55 GPa and 0.90 ± 0.39 GPa (Mean ± S.D.), respectively. There was no significant difference between the two values. These results indicate that the elastic modulus of the sub-fibrils in the surface layers of fibrils may not be significantly different from that of whole fibrils in the longitudinal direction.
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A new approach of measuring through-thickness Young's moduli of composite materials using nanoindentation was proposed. First, an approximate expression of the reduced modulus of nanoindentation was introduced for orthotropic composites. Second, spherical nanoindentation was conducted for an E-glass fiber/vinyl ester composite system, and measured Young's modulus was quite consistent with the previously reported value for a similar material system.
Orthotropic material
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