Measurement Of Elastic Modulus Research Articles

Medición del módulo de elasticidad en materiales de ingeniería utilizando la técnica de indentación instrumentada y de ultrasonido

Currently, the acoustic and nanoindentation techniques are two of the most used techniques for material elastic modulus measurement. In this article fundamental principles and limitations of both techniques are shown and discussed. Last advances in nanoindentation technique are also reviewed. An experimental study in ceramic, metallic, composite and single crystals was also done. Results shown that ultrasonic technique is capable to provide results in agreement with those reported in literature. However, ultrasonic technique does not allow measuring the elastic modulus of some small samples and single crystals. On the other hand, the nanoindentation technique estimates the elastic modulus values in reasonable agreement with those measured by acoustic methods, particularly in amorphous materials, while in some policristaline materials some deviation from expected values was obtained.

Mechanical and physical characterization of copper foam

A lost carbonate sintering process in powder metallurgy has been used to prepare copper foam of low to medium porosities with controlled pore size, shape, and distribution. The compressive properties of the copper foams have been investigated for different metal volume fractions ranging from 15–100%. The elastic moduli measurements in good agreement with Mori-Tanaka predictions for the two-phase mixtures. The microstructure, the electrical resistivity, and the thermal conductivity were also studied.

OS0815 遮熱コーティングの機械的特性評価法の標準化に向けて : ナノインデンテーション法による弾性係数測定(OS08-04 薄膜・皮膜の特性評価とその膜構造4,OS08 薄膜・皮膜の特性評価とその膜構造(2))

NEDO委託「耐熱コーティング膜の特性評価試験方法に関する標準化事業」において,耐熱コーティングの弾性係数を積層曲げ法により測定する方法のJIS化を検討している.その裏付けのために,8mass%Y_2O_3-ZrO_2およびCoNiCrAlYを溶射した試験片の弾性係数をインデンテーション法により測定した.その結果,弾性係数は皮膜厚さにほとんど依存せず,最大圧子押込み深さが増加すると単調に減少するとともに,本実験で得られた弾性係数は,積層曲げ試験方法で求めたそれに比べると高くなることが明らかになった.

Plutonium Elastic Moduli, Electron Localization, and Temperature

AbstractIn almost all materials, compression is accompanied naturally by stiffening. Even in materials with zero or negative thermal expansion, where warming is accompanied by volume contraction it is the volume change that primarily controls elastic stiffness. Not so in the metal plutonium. In plutonium, alloying with gallium can change the sign of thermal expansion, but for the positive-thermal-expansion monoclinic phase as well as the face-centered-cubic phase with either sign of thermal expansion, and the orthorhombic phase, recent measurements of elastic moduli show soften on warming by an order of magnitude more than expected, the shear and compressional moduli track, and volume seems irrelevant. These effects point toward a novel mechanism for electron localization, and have important implication for the pressure dependence of the bulk compressibility.

2P-196 バクテリアべん毛弾性率の直接測定(分子モーター(2),第46回日本生物物理学会年会)

2P-196 バクテリアべん毛弾性率の直接測定(分子モーター(2),第46回日本生物物理学会年会)

OS0814 遮熱コーティングの機械的特性評価法の標準化に向けて : 積層梁の曲げによる弾性係数測定(OS08-04 薄膜・皮膜の特性評価とその膜構造4,OS08 薄膜・皮膜の特性評価とその膜構造(2))

OS0814 遮熱コーティングの機械的特性評価法の標準化に向けて : 積層梁の曲げによる弾性係数測定(OS08-04 薄膜・皮膜の特性評価とその膜構造4,OS08 薄膜・皮膜の特性評価とその膜構造(2))

Determination of the Impact of Hepatitis C Virus on Insulin Resistance and Arterial Stiffness in Hemodialysis Patients

Aim. It has been shown that Hepatitis C virus (HCV) seropositivity and carotis artery plaque formation are independently correlated in the general population. Insulin resistance is also a risk factor for atherosclerosis. The association between HCV and type 2 diabetes mellitus is known. Determination of the impact of HCV on insulin resistance and arterial stiffness in hemodialysis patients would help to prevent related cardiovascular complications. Methods. Thirty-seven HCV(+) and 30 HCV(-) HD patients were enrolled in this study. All patients were non-diabetic. Insulin resistance was assessed by “HOMA-IR.” Arterial stiffness was measured by “stiffness index b” and “elastic modulus.”Results. In the HCV(+) group, there were 20 males and 17 females, while the HCV(-) group had 19 males and 11 females. The mean age was 43.4 ± 16.7 years and 44.5 ± 16.8 years, respectively. The HOMA-IR was 1.50 in HCV(+) group and 1.31 in HCV(-) group (p > 0.05). Stiffness index b and elastic modulus measurements revealed no difference between groups. In the HCV(+) group, arterial stiffness parameters were correlated with age, white blood cell, thrombocyte, total and LDL cholesterol, uric acid, mean arterial pressure, diastolic blood pressure, and HOMA-IR. There was no association between arterial stiffness and the above-mentioned parameters in the HCV(-) group.Conclusion. We found that there was no association of arterial stiffness in HCV(+) patients with insulin resistance. Further studies with larger patient groups and more sensitive methods of detecting HCV are needed. This study is the first in literature on this issue.

Elastic modulus of biomedical titanium alloys by nano-indentation and ultrasonic techniques—A comparative study

The elastic modulus of near β and β titanium alloys was measured by nano-indentation and ultrasonic techniques. The data obtained from both the experiments were analyzed and compared with each other. The effects of composition and heat treatment on elastic modulus of the material are discussed. The elastic modulus of β Ti–35Nb–5.7Ta–7.2Zr (TNTZ) was found to be half of the elastic modulus of the titanium. Near β Ti–13Zr–13Nb (TZN) alloy hot worked at 800 °C and solution treated at 800 °C followed by water quenching also showed low elastic modulus value. The accuracy of these two elastic modulus measurement techniques is discussed in terms of microstructures.

Characterization by ultra-micro indentation of an oxidized epoxy polymer: Correlation with the predictions of a kinetic model of oxidation

This study aims to understand better the influence of thermo-oxidation on the degradation of an epoxy resin used as the matrix of aeronautical composite laminates. Neat epoxy resin plates have been aged at 150 °C, under vacuum and ambient air. Using an instrumented ultra-micro indentation device, modifications of mechanical properties due to oxidation at elevated temperature are characterized through the measurements of elastic indentation modulus, Vickers hardness and indentation creep. By using a kinetic model of oxidation developed specifically for this epoxy resin, the local values of oxidation product concentration are calculated and correlated to experimental indentation measurements.

EXPERIMENTAL NANOMECHANICS OF ONE-DIMENSIONAL NANOMATERIALS BY IN SITU MICROSCOPY

This paper provides a comprehensive review on the methodological development and technical applications of in situ microscopy, including transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM), developed in the last decade for investigating the structure-mechanical-property relationship of a single one-dimensional nanomaterial, such as nanotube, nanowire and nanobelt. The paper covers both the fundamental methods and detailed applications, including AFM-based static elastic and plastic measurements of a carbon nanotube, external field-induced resonance dynamic measurement of elastic modulus of a nanotube/nanowire, nano-indentation, and in situ plastic deformation process of a nanowire. Details are presented on the elastic property measurements and direct imaging of plastic to superplastic behavior of semiconductor nanowires at atomic resolution, providing quantitative information on the mechanical behavior of nanomaterials. The studies on the Si and SiC nanowires clearly demonstrated their distinct, "unexpected" and superior plastic mechanical properties. Finally, a perspective is given on the future of nanomechanics.

Use of associating polymers as multifunctional thickeners: studies of Their structure in aqueous solutions via nmr, qels, fluorescence, And rheology measurements

The solution properties of an associating polymer were studied by NMR, quasi‐elastic light scattering (QELS), fluorescence, and rheology measurements. An associative thickening (AT) polymer was designed having a nonionic poly(ethylene oxide) backbone with long alkyl chains at both ends to achieve high viscosity even at relatively high salt concentrations and over a wide pH range. This study focuses on the associative state of the polymer in aqueous solutions at various polymer concentrations. In a fluorescence probe study using pyrene a spectral change in the I3/I1 ratio was observed for pyrene at a polymer concentration (Cp) of 3 x 10‐4%, indicating an apparent critical concentration (cmc) of the amphiphilic polymer. The viscosity, self‐diffusion coefficient (Dsel), and hydrodynamic size (Rh) distribution measurements at various Cp all suggest that there is a second transition at Cp≅ 0.4%. Although we observed the discontinuity in viscosity, Dsel, and Rh at Cp≅ 0.4%, no changes in the relaxation times (T1 and T2) were recognized for either the alkyl chain or the ethylene oxide moiety of the polymer at C p= 0.1–1%. These data suggest that there are no structural changes or phase transitions at Cp≅ 0.4%, but that intermicellar networks are presumably formed by bridging of the end alkyl groups of the polymer, which is driven by hydrophobic forces. Because the polymer forms networks by hydrophobic interaction and the polymer itself is nonionic, the viscosity of the polymer solution was influenced very little by either the addition of salt or a pH change, as would be expected. The dynamic viscoelastic study revealed that the polymer solution exhibits a single mode Maxwell type relaxation behavior with a terminal relaxation time of about 0.61 s, which imparts a unique flow appearance to the polymer solutions. The time course measurements of the dynamic elastic modulus of the stratum corneum revealed that the polymer has excellent potential for skin softening. It was concluded that the associative thickening polymer not only is a useful thickener with a salt and pH tolerance but also has beneficial skincare effects.

Influence of polishing time on thermo-oxidation characterization of isothermally aged PMR-15 resin

The effect of polishing time on measured oxidation thickness and elastic modulus of isothermally aged PMR-15 neat resin was investigated. A specimen aged 956 h in ambient air at 288 °C (550 °F) was selected for this study. Thermo-oxidation of the specimen results in a surface oxidation layer with different stiffness and polishing characteristics than the interior of the specimen. The specimen was repolished at consecutive time periods from a quick polishing time to extensive polishing time. A white light interferometer was used as a surface profiler to measure height variations from the specimen edges into the interior of the material. Subsequently, optical microscopy and nanoindentation experiments were conducted to correlate observations of oxidation thickness and elastic modulus measurements with polishing time. The modulus profiles obtained from nanoindentation experiments indicate formation of an outer brittle layer followed by a sharp drop in the transition region to the unoxidized interior. The oxidized material is polished at a greater rate than the unoxidized material. The maximum variation in the surface profile from polishing was limited to 5 μm across the oxidation layer (∼150 μm), which results in a slope of ∼2° over the oxidized region. Optical measurements of thickness of oxidized layer and transition region are in good agreement with the height and modulus profiles obtained using the interferometer and nanoindenter, respectively. Results from three techniques show that the measured oxidation thickness and elastic modulus are relatively independent of the polishing time.

Dielectric relaxation and phase transitions at cryogenic temperatures in0.65[Pb(Ni1∕3Nb2∕3)O3]−0.35PbTiO3ceramics

Dielectric measurements on $0.65[\mathrm{Pb}({\mathrm{Ni}}_{1∕3}{\mathrm{Nb}}_{2∕3}){\mathrm{O}}_{3}]\ensuremath{-}0.35\mathrm{Pb}\mathrm{Ti}{\mathrm{O}}_{3}$ ceramic in the temperature range $90--470\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ show a relaxor ferroelectric transition around $350\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ with a Vogel-Fulcher freezing temperature of $338\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and an appearance of a nonergodic relaxor ferroelectric phase of tetragonal structure at room temperature. This nonergodic phase reenters into the relaxor state at low temperatures as evidenced by the appearance of a frequency dependent anomaly in the imaginary part of the dielectric constant around $160\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, similar to those reported in other relaxor ferroelectric based morphotropic phase boundary ceramics. The polarization relaxation time for the $160\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ anomaly also follows Vogel-Fulcher type temperature dependence. Temperature dependent magnetization measurements show that this low temperature anomaly is not linked with any magnetic transition. Elastic modulus and low temperature x-ray diffraction measurements reveal a tetragonal to monoclinic phase transition around $225\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. It is argued that the low temperature dielectric dispersion around $160\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ results from the freezing of mesoscopic conformally miniaturized monoclinic domains formed inside the parent tetragonal domains below the structural phase transition temperature of $225\phantom{\rule{0.3em}{0ex}}\mathrm{K}$.

Damage zone produced by the bombardment of stainless steel using Ti nitride PVD coatings

This paper presents the damage zone and defects produced by TiN thin film deposition on stainless steel using DC magnetron sputtering to produce collisions between the TiN ions and the substrate. The PVD process used a low operative pressure, reducing the bombardment damage on the substrate, in comparison with other methods. Internal friction (IF) and elastic modulus measurements were carried out in TiN-PVD coated AISI 304 stainless steel, using a sub-resonant torsion pendulum ( f ≅ 1 Hz) and a vibrant-reed instrument ( f ≅ 10 3 Hz). Some experiments showed several internal friction peaks, which are attributed to dislocation relaxation and to martensitic transformation from γ to α′. The characterization was carried out with X-ray, AFM and SEM. Analysis of X-ray peaks indicates a residual deformation in the order of 0.0005–0.0009 for γ-phase and 0.0006–0.00204 for α′-phase. Two methods are presented to determine the adhesion energy by IF in coated materials: for the first the enthalpy is determined by means of isochronal IF measurements, while for the second it is determined using isothermal measurements. These produce an image of damage caused by the bombardment on the substrate, especially of the residual defects.

The Universality of Energy Spectrum of Phonon and Vacancy Excitations in Solid Helium

The most careful measurements on the specific heat C(T) and dP/dT (P is the pressure, T is the temperature) are analysed using a model where the thermodynamic properties of 3He and 4He crystals are described by a sum of phonon and vacancy contributions. The analysis, in which the Debye model of phonons and the Hetherington model for wide-band vacancies are used, yields a universal molar volume depence for the Debye temperature ΘD and the vacancy activation energy QV, and constant values for the Gruneisen parameters in the molar volume range of 14–24 cm3/mol. The ΘD values are found to be in good agreement with the data obtained from the elastic moduli measurements and with Horner’s theoretical calculations. The QV values are in good agreement with the X-ray measurements on the temperature dependences of 3He and 4He crystal lattice parameters analysed in terms of the Hetherington model.

Tuning of hollow fiber membrane properties using different bore fluids

Polymer solutions of a modified poly(ether ether ketone) and poly(vinyl pyrrolidone) in dimethylformamide were spun to prepare hollow fiber membranes by dry–wet spinning method. The influence of R OH bore fluids (BF), with R H; CH 3; C 2H 5; n-C 3H 7 or n-C 4H 9, on morphology and transport and mechanical properties was studied by electron scanning microscopy (SEM) and by measurements of water permeability (WP), dextrane rejection, tensile strength and elastic modulus. The results were discussed on the basis of ternary phase diagrams and Hildebrand solubility parameters, δ. The use of water as the bore fluid resulted in typical UF membranes with the lowest water permeability (158 l h −1 m −2 bar −1) and the highest dextrane rejection (99%). On the other hand, n-alkyl alcohols as the bore fluid produced MF membranes with a water permeability, increasing from about 600 to 1200 l h −1 m −2 bar −1 with increasing alkyl chain length, and with a low dextrane rejection.

Temperature-dependent elastic moduli of epoxies measured by DMA and their correlations to mechanical testing data

Measurements of temperature-dependant elastic moduli of two cured epoxy systems and two silica–epoxy nanocomposites were conducted using dynamic mechanical analysis (DMA) methods with different loading fixtures. Comparisons of the results were made with those obtained from tests with different loading modes and from mechanical testing results under various temperatures. Discrepancies were found between the temperature-dependant elastic moduli measured by DMA with different loading modes and varying test conditions, such as machine compliance, drive amplitude, loading frequency and contact stresses, although the specimen-to-specimen deviations were relatively small between specimens tested with the same fixture and similar test parameters. However, the elastic moduli obtained from DMA measurements can be used to represent the temperature dependence of elastic modulus once corrections are made based on the static mechanical testing data obtained at ambient temperature. Although there were discrepancies in magnitude between the original temperature-dependant elastic moduli determined by DMA and those measured by mechanical tests, very good agreement was found for the two epoxy systems and two silica–epoxy nanocomposites after the DMA data were shifted.

Theoretical modelling and implementation of elastic modulus measurement at the nanoscale using atomic force microscope

Quantitative studies of mechanical behaviour and primarily elastic modulus are essential for material science at the nanometer scale. AFM nanoindentation is the most promising approach to address the problem. In our study we perform AFM-based nanoindentation (deflection-versus-distance curves) on a set of polymer materials with microscopic moduli ranging from 1 MPa to 10 GPa. The measurements were done with probes of different tip shapes and force levels from 100 nN to 3 μN. The tip geometry was evaluated from TEM and SEM micrographs and piecewise linearly interpolated for the use of analysis software; probe spring constant was determined from thermal tune data. The comparative analysis of nanoindentation data was carried out using models of Sneddon and Oliver-Pharr. We derived Sneddon's integrals in closed form for any practical tip shape using a piecewise linear interpolation. Oliver-Pharr's method to account for plasticity for the unloading curve was adapted for Sneddon's integrals. An interactive software implementation with both models was developed and applied.

Nano-Mechanical Properties of Coiled Carbon Nanotube Reinforced Epoxy Composites

The applications of carbon nanotubes benefit to a wide range of engineering, applied physics and biomaterials areas for their superior mechanical and electrical properties. Recently, coiled carbon nanotube (CCNT) has opened a new alternative to reinforce traditional advanced composites. Their coiled shapes are considered to induce mechanical interlocking between the nanotubes and matrix which result in the enhancement of fracture toughness and mechanical strength of the composites. In this study, nanomechanical properties of CCNT reinforced epoxy composites with varying weight percentages (0, 1, 3, and 5 wt %) of nanotubes were measured by the nanoindentation technique. Hardness and elastic modulus measurement of the composites were conducted.

All-electrical indentation shear modulus and elastic modulus measurement using a piezoelectric cantilever with a tip

We have investigated an all-electrical indentation shear modulus and elastic modulus measurement technique using piezoelectric cantilever sensors with a tip for potential in vivo applications. A piezoelectric cantilever with a tip was capable of carrying out compression, shear, indentation, and indentation shear tests, where compression and shear tests refer to those where the sample is not confined by a container and the contact area of the cantilever is the same as or larger than the sample surface area and the indentation and indentation shear tests are those where the contact area of the cantilever is smaller than the sample surface area. Because the cantilever could measure both the elastic modulus and the shear modulus, Poisson’s ratio of a sample could be determined from the ratio of the shear modulus to the elastic modulus with no presumption. We showed that the experimental elastic moduli and shear moduli obtained from the indentation and indentation shear tests agree with those obtained from the compression and shear tests. Furthermore, we showed that the same elastic moduli and the same shear moduli could be obtained either by using the displacement measurements or by the induced voltage measurements across the sensing piezoelectric layer. With a model tissue consisting of modeling clay embedded in gelatin, we demonstrated that the indentation compression and indentation shear tests could produce two-dimensional elastic and shear moduli maps or images that accurately showed the size and location of the modeling clay inclusion.