Determination of the Young’s modulus and hysteresis by the indentation method

Bulychev, S. I.

doi:10.1134/1.1342446

Cited by 12 publications

(13 citation statements)

References 2 publications

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“…The indentation load‐displacement response of developed polymer composites was obtained using an instrumented hardness tester with a Vickers diamond indenter with a load of 0.3 N. For S6 (HDPE‐40 vol % HAp), Vickers hardness was measured in a Vickers microindenter using a load of 0.4 N. It can be recalled that, Bulychev et al30 was first to use the load‐displacement sensing indentation testing in the early 1970's, as an experiment tool for measuring hardness and elastic modulus. In case of polymer‐based materials, the instrumented hardness measurement technique is considered as a useful technique to examine the extent to which the load‐displacement behavior is influenced by viscoelastic deformation.…”

Section: Discussionmentioning

confidence: 99%

HDPE‐Al₂O₃‐HAp composites for biomedical applications: Processing and characterizations

2008

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The objective of this work is to demonstrate how the stiffness, hardness, as well as the biocompatibility property, of bioinert high-density polyethylene (HDPE) can be significantly improved by the combined addition of both bioinert and bioactive ceramic fillers. For this purpose, different volume fractions of hydroxyapatite and alumina, limited to a total of 40 vol %, have been incorporated in HDPE matrix. All the hybrid composites and monolithic HDPE were developed under optimized hot pressing condition (130 degrees C, 0.5 h, 92 MPa pressure). The results of the mechanical property characterization reveal that higher elastic modulus (6.2 GPa) and improved hardness (226.5 MPa) could be obtained in the developed HDPE-20 vol %-HAp-20 vol % Al(2)O(3) composite. Under the selected fretting conditions against various counterbody materials (steel, Al(2)O(3), and ZrO(2)), an extremely low COF of (0.07-0.11) and higher wear resistance (order of 10(-6) mm(3)/Nm) are obtained with the HDPE/20 vol % HAp/20 vol % Al(2)O(3) composite in both air and simulated body fluid environment. Importantly, in-vitro cell culture study using L929 fibroblast cells confirms favorable cell adhesion properties in the developed hybrid composite.

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Section: Discussionmentioning

confidence: 99%

HDPE‐Al₂O₃‐HAp composites for biomedical applications: Processing and characterizations

2008

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“…On each sample 2 series of statistical nanoindentation tests were carried out that differ in the loading protocol: the first series assesses the microstructure from indentation hardness and indentation stiffness results; obtained by a trapezoidal load history with a maximum load of P max ϭ 2 mN, applied in 10 s, kept constant over 5 s and unloaded in 10 s. Following fast loading, the 5-s dwelling time is short enough to ensure that the indentation hardness, H ϭ P max /A c (with A c the projected area of contact between the indenter probe and the indented surface), is representative of the strength content (19,23,24). In turn, the unloading is fast enough so that the indentation modulus M, determined from the unloading slope S ϭ (dP/ dh) hϭh max at the end of the holding phase truly relates to the elasticity content of the indented material (25), namely the indentation modulus M ϭ E/(1 Ϫ 2 ) ϭ S/(2a U ), with E the Young's modulus, the Poisson's ratio, and a U ϭ ͌ A c / the radius of contact between the indenter probe and the indented surface upon unloading (21,22,26). The load protocol of the second series differs from the first in a 180-s long dwelling period, which allows the assessment of the contact creep compliance rate, L (t) Х 2a U ḣh/P max , and the creep compliance, L(t) ϭ 2a U ⌬h(t)/P max ϩ const, from the time-dependent indentation depth rate ḣ(t) and the change in indentation depth ⌬h(t) ϭ h(t) Ϫ h 0 in excess of the indentation depth h 0 Ϸ 200 nm Ϯ 45 nm recorded during the 10-s loading to P max ϭ 2 mN (Fig.…”

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confidence: 99%

Nanogranular origin of concrete creep

Vandamme

Ulm

2009

Proc. Natl. Acad. Sci. U.S.A.

379

192

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Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium-silicate-hydrates (C-S-H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C-S-H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C-S-H forms: low density, high density, ultra-high density. We demonstrate that the creep rate (Ϸ1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years.C oncrete is the most-used construction material on earth. The annual worldwide production stands at 20 billion tons and increases per annum by 5%. However, the fundamental causes of concrete creep are still an enigma, and have deceived many decoding attempts from both experimental (1-3) and theoretical sides (4-8). In the United States alone, concrete creep is partly responsible for an estimated 78.8 billion dollars required annually for highway and bridge maintenance. Although it is generally agreed that the complex creep behavior of concrete materials is largely related to the viscoelastic response of the primary hydration product and binding phase of hardened Portland cement paste, the calcium-silicate-hydrate (C-S-H), the creep properties of C-S-H have never been measured directly. C-S-H precipitates when cement and water are mixed, as clusters of nanoscale colloidal particles (9, 10) that cannot be recapitulated ex situ in bulk form suitable for macroscopic testing. Over decades, therefore, concrete creep properties have been probed on the composite scale of mortar and concrete (11), with the conclusion that there are 2 distinct creep phenomena at play ( Fig. 1 A and B): a short-term volumetric creep and a long-term creep associated with shear deformation (3,7,12,13), with a creep rate evolving as a power function t Ϫn of exponent n between 0.9 and 1 (14). The assessment of this long-term creep is most critical for the durability of concrete structures, and requires, for a specific concrete composition and structural application, years of expensive macroscopic testing (11,14). After more than 40 years of research (4-8), basic questions persist regarding the physical origin of this logarithmic creep and its link with microstructure and composition.In this study, we investiga...

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“…The introduction of a method of determination of Young's modulus according to the indentation diagram was a very important step in interpretation of indentation tests. The method was introduced by Bulychev, Alekhin, Shorshorov and co-workers in 1975 (see Bulychev et al . 1975Bulychev et al .…”

Section: Introductionmentioning

confidence: 99%

Evaluation of elastic modulus of materials by adhesive (no–slip) nano–indentation

Borodich

Keer

2004

Proc. R. Soc. Lond. A

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Results of Mossakovskii's analysis for the elastic, adhesive (no-slip) contact between a rigid, axisymmetric punch and an isotropic, elastic half-space are developed in order to show that a simple relation exists between the contact stiffness, the contact area and the elastic modulus. The relation is similar to the Bulychev-Alekhin-Shorshorov equation, which is commonly used for evaluation of elastic modulus of materials by nano-indentation. The final formula differs from the frictionless case by a factor that depends on the Poisson ratio of the material. The bounds for the values of the factor are estimated. Similar to the frictionless analysis performed by Pharr, Oliver and Brotzen, the relation is not dependent on the geometry of the punch.

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Determination of the Young’s modulus and hysteresis by the indentation method

Cited by 12 publications

References 2 publications

HDPE‐Al₂O₃‐HAp composites for biomedical applications: Processing and characterizations

HDPE‐Al₂O₃‐HAp composites for biomedical applications: Processing and characterizations

Nanogranular origin of concrete creep

Evaluation of elastic modulus of materials by adhesive (no–slip) nano–indentation

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Determination of the Young’s modulus and hysteresis by the indentation method

Cited by 12 publications

References 2 publications

HDPE‐Al2O3‐HAp composites for biomedical applications: Processing and characterizations

HDPE‐Al2O3‐HAp composites for biomedical applications: Processing and characterizations

Nanogranular origin of concrete creep

Evaluation of elastic modulus of materials by adhesive (no–slip) nano–indentation

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Product

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HDPE‐Al₂O₃‐HAp composites for biomedical applications: Processing and characterizations

HDPE‐Al₂O₃‐HAp composites for biomedical applications: Processing and characterizations