Elastic Properties of Normal and Binormal Helical Nanowires

2006 ◽  
Vol 963 ◽  
Author(s):  
Alexandre Fontes da Fonseca ◽  
C P Malta ◽  
Douglas S Galvão
Keyword(s):  
Simple Model ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Cross Section ◽  
Young's Modulus ◽  
Helical Axis ◽  
Geometric Features ◽  
Kirchhoff Rod ◽  
Rod Model ◽  
The Cross

ABSTRACTA helical nanowire can be defined as being a nanoscopic rod whose axis follows a helical curve in space. In the case of a nanowire with asymmetric cross section, the helical nanostructure can be classified as normal or binormal helix, according to the orientation of the cross section with respect to the helical axis of the structure. In this work, we present a simple model to study the elastic properties of a helical nanowire with asymmetric cross section. We use the framework of the Kirchhoff rod model to obtain an expression relating the Hooke's constant, h, of normal and binormal nanohelices to their geometric features. We also obtain the Young's modulus values. These relations can be used by experimentalists to evaluate the elastic properties of helical nanostructures. We showed that the Hooke's constant of a normal nanohelix is higher than that of a binormal one. We illustrate our results using experimentally obtained nanohelices reported in the literature.

scholarly journals Optimized CNT-PDMS Flexible Composite for Attachable Health-Care Device

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4523 ◽  
Author(s):  
Jian Du ◽  
Li Wang ◽  
Yanbin Shi ◽  
Feng Zhang ◽  
Shiheng Hu ◽  
...  
Keyword(s):  
Composite Material ◽  
Percolation Threshold ◽  
Young’S Modulus ◽  
Cross Section ◽  
Young's Modulus ◽  
Large Strain ◽  
Weight Ratio ◽  
Linear Range ◽  
Wide Range ◽  
The Cross

The CNT-PDMS composite has been widely adopted in flexible devices due to its high elasticity, piezoresistivity, and biocompatibility. In a wide range of applications, CNT-PDMS composite sensors were used for resistive strain measurement. Accordingly, the percolation threshold 2%~4% of the CNT weight ratio in the CNT-PDMS composite was commonly selected, which is expected to achieve the optimized piezoresistive sensitivity. However, the linear range around the percolation threshold weight ratio (2%~4%) limits its application in a stable output of large strain (>20%). Therefore, comprehensive understanding of the electromechanical, mechanical, and electrical properties for the CNT-PDMS composite with different CNT weight ratios was expected. In this paper, a systematic study was conducted on the piezoresistivity, Young’s modulus, conductivity, impedance, and the cross-section morphology of different CNT weight ratios (1 to 10 wt%) of the CNT-PDMS composite material. It was experimentally observed that the piezo-resistive sensitivity of CNT-PDMS negatively correlated with the increase in the CNT weight ratio. However, the electrical conductivity, Young’s modulus, tensile strength, and the linear range of piezoresistive response of the CNT-PDMS composite positively correlated with the increase in CNT weight ratio. Furthermore, the mechanism of these phenomena was analyzed through the cross-section morphology of the CNT-PDMS composite material by using SEM imaging. From this analysis, a guideline was proposed for large strain (40%) measurement applications (e.g., motion monitoring of the human body of the finger, arm, foot, etc.), the CNT weight ratio 8 wt% was suggested to achieve the best piezoresistive sensitivity in the linear range.

Vibration of Zinc Oxide Nanowires in Electric Field

2017 ◽  
Author(s):  
Lifeng Wang ◽  
Saisai Liu ◽  
Jianpeng Yi
Keyword(s):  
Electric Field ◽  
Young’S Modulus ◽  
Cross Section ◽  
Md Simulation ◽  
Young's Modulus ◽  
Continuum Theory ◽  
Zno Nanowires ◽  
Vibration Frequencies ◽  
Polarization Direction ◽  
The Cross

This paper studies the vibration of Zinc oxide (ZnO) nanowires in electric field via molecular dynamics (MD) simulation and continuum beam models. First, the size effects of the equivalent Young’s modulus and piezoelectric constant of ZnO nanowires are obtained by MD simulation and characterized by core-shell model. The piezoelectric constants of ZnO nanowires decrease with the rising of the size of cross section. The equivalent tensile and bending Young’s modulus of ZnO nanowires in polarization direction increases with the increasing of the cross section size. The equivalent tensile and bending Young’s modulus in polarization direction predicted by core-shell model is in good agreement with MD simulation. Then, the vibration of the cantilevered ZnO nanobeam is simulated by MD. When the cross section size becomes larger, the vibration frequencies predicted by continuum theory coincide with those obtained by MD simulation better. Finally, the effect of electric field on vibration frequency of a ZnO nanowire is studied by MD simulation and continuum beam models. It is found that the natural frequencies rise with the increasing of electric field for the case of positive electric field in polarization direction. But the natural frequencies will decrease with the increasing of negative electric field when the intensity of the electric field is relatively weak. The natural frequency is hard to be obtained when the phase transition is occurring in relatively strong negative electric field. The vibration frequencies of the cantilevered Timoshenko beam with axial force due to the effects of electric field are obtained. The frequencies obtained by Timoshenko beam model agree with MD results very well. The vibration frequencies of the continuum theory agree with MD results better when the size of the cross section increases. The vibration frequencies of the ZnO nanowire keep constant when the direction of electric field is perpendicular to the polarization direction.

scholarly journals A Quasi-Static Quantitative Ultrasound Elastography Algorithm Using Optical Flow

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3010
Author(s):  
Raphael Lamprecht ◽  
Florian Scheible ◽  
Marion Semmler ◽  
Alexander Sutor
Keyword(s):  
Optical Flow ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Young's Modulus ◽  
Image Data ◽  
Maximum Error ◽  
Ultrasound Elastography ◽  
Static Compression ◽  
Tissue Properties ◽  
A Performance

Ultrasound elastography is a constantly developing imaging technique which is capable of displaying the elastic properties of tissue. The measured characteristics could help to refine physiological tissue models, but also indicate pathological changes. Therefore, elastography data give valuable insights into tissue properties. This paper presents an algorithm that measures the spatially resolved Young’s modulus of inhomogeneous gelatin phantoms using a CINE sequence of a quasi-static compression and a load cell measuring the compressing force. An optical flow algorithm evaluates the resulting images, the stresses and strains are computed, and, conclusively, the Young’s modulus and the Poisson’s ratio are calculated. The whole algorithm and its results are evaluated by a performance descriptor, which determines the subsequent calculation and gives the user a trustability index of the modulus estimation. The algorithm shows a good match between the mechanically measured modulus and the elastography result—more precisely, the relative error of the Young’s modulus estimation with a maximum error 35%. Therefore, this study presents a new algorithm that is capable of measuring the elastic properties of gelatin specimens in a quantitative way using only the image data. Further, the computation is monitored and evaluated by a performance descriptor, which measures the trustability of the results.

scholarly journals A parametric prediction of the Young’s modulus of polymers enhanced with ΜWCNTs

2018 ◽  
Vol 233 ◽  
pp. 00025
Author(s):  
P.V. Polydoropoulou ◽  
K.I. Tserpes ◽  
Sp.G. Pantelakis ◽  
Ch.V. Katsiropoulos
Keyword(s):  
Young’S Modulus ◽  
Elastic Properties ◽  
Young's Modulus ◽  
Experimental Results ◽  
Scale Model ◽  
Fe Model ◽  
Multi Scale ◽  
Unit Cells ◽  
Random Dispersion

In this work a multi-scale model simulating the effect of the dispersion, the waviness as well as the agglomerations of MWCNTs on the Young’s modulus of a polymer enhanced with 0.4% MWCNTs (v/v) has been developed. Representative Unit Cells (RUCs) have been employed for the determination of the homogenized elastic properties of the MWCNT/polymer. The elastic properties computed by the RUCs were assigned to the Finite Element (FE) model of a tension specimen which was used to predict the Young’s modulus of the enhanced material. Furthermore, a comparison with experimental results obtained by tensile testing according to ASTM 638 has been made. The results show a remarkable decrease of the Young’s modulus for the polymer enhanced with aligned MWCNTs due to the increase of the CNT agglomerations. On the other hand, slight differences on the Young’s modulus have been observed for the material enhanced with randomly-oriented MWCNTs by the increase of the MWCNTs agglomerations, which might be attributed to the low concentration of the MWCNTs into the polymer. Moreover, the increase of the MWCNTs waviness led to a significant decrease of the Young’s modulus of the polymer enhanced with aligned MWCNTs. The experimental results in terms of the Young’s modulus are predicted well by assuming a random dispersion of MWCNTs into the polymer.

scholarly journals High-Temperature Elastic Properties of Yttrium-Doped Barium Zirconate

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 968
Author(s):  
Fumitada Iguchi ◽  
Keisuke Hinata
Keyword(s):  
High Temperature ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Measurement Method ◽  
Young's Modulus ◽  
Barium Zirconate ◽  
Shear Moduli ◽  
Ceramic Fuel ◽  
Yttrium Concentration ◽  
Ceramic Fuel Cells

The elastic properties of 0, 10, 15, and 20 mol% yttrium-doped barium zirconate (BZY0, BZY10, BZY15, and BZY20) at the operating temperatures of protonic ceramic fuel cells were evaluated. The proposed measurement method for low sinterability materials could accurately determine the sonic velocities of small-pellet-type samples, and the elastic properties were determined based on these velocities. The Young’s modulus of BZY10, BZY15, and BZY20 was 224, 218, and 209 GPa at 20 °C, respectively, and the values decreased as the yttrium concentration increased. At high temperatures (>20 °C), as the temperature increased, the Young’s and shear moduli decreased, whereas the bulk modulus and Poisson’s ratio increased. The Young’s and shear moduli varied nonlinearly with the temperature: The values decreased rapidly from 100 to 300 °C and gradually at temperatures beyond 400 °C. The Young’s modulus of BZY10, BZY15, and BZY20 was 137, 159, and 122 GPa at 500 °C, respectively, 30–40% smaller than the values at 20 °C. The influence of the temperature was larger than that of the change in the yttrium concentration.

Effects of cross-sessional area and aspect ratio coupled with orientation on mechanical properties and deformation behavior of Cu nanowires

2021 ◽  
Author(s):  
Hui Cao ◽  
Wenke Chen ◽  
Zhiyuan Rui ◽  
Changfeng Yan
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Cu Nanowires ◽  
The Cross

Abstract Metal nanomaterials exhibit excellent mechanical properties compared with corresponding bulk materials and have potential applications in various areas. Despite a number of studies of the size effect on Cu nanowires mechanical properties with square cross-sectional, investigations of them in rectangular cross-sectional with various sizes at constant volume are rare, and lack of multifactor coupling effect on mechanical properties and quantitative investigation. In this work, the dependence of mechanical properties and deformation mechanisms of Cu nanowires/nanoplates under tension on cross-sessional area, aspect ratio of cross-sectional coupled with orientation were investigated using molecular dynamics simulations and the semi-empirical expressions related to mechanical properties were proposed. The simulation results show that the Young’s modulus and the yield stress sharply increase with the aspect ratio except for the <110>{110}{001} Cu nanowires/nanoplates at the same cross-sectional area. And the Young’s modulus increases while the yield stress decreases with the cross-sectional area of Cu nanowires. However, both of them increase with the cross-sectional area of Cu nanoplates. Besides, the Young’s modulus increases with the cross-sectional area at all the orientations. The yield stress shows a mildly downward trend except for the <111> Cu nanowires with increased cross-sectional area. For the Cu nanowires with a small cross-sectional area, the surface force increases with the aspect ratio. In contrast, it decreases with the aspect ratio increase at a large cross-sectional area. At the cross-sectional area of 13.068 nm2, the surface force decreases with the aspect ratio of the <110> Cu nanowires while it increases at other orientations. The surface force is a linearly decreasing function of the cross-sectional area at different orientations. Quantitative studies show that Young’s modulus and yield stress to the aspect ratio of the Cu nanowires satisfy exponent relationship. In addition, the main deformation mechanism of Cu nanowires is the nucleation and propagation of partial dislocations while it is the twinning-dominated reorientation for Cu nanoplates.

Elastic properties and breaking strengths of GaS, GaSe and GaTe nanosheets

Nanoscale ◽  
2018 ◽  
Vol 10 (27) ◽  
pp. 13022-13027 ◽  
Author(s):  
Basant Chitara ◽  
Assaf Ya'akobovitz
Keyword(s):  
Atomic Force Microscopy ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Young's Modulus ◽  
Force Microscopy ◽  
Atomic Force ◽  
Maximal Strain

The present study highlights the elastic properties of suspended GaS, GaSe and GaTe nanosheets using atomic force microscopy. GaS exhibited the highest Young's modulus (∼173 GPa) among these nanosheets. These materials can withstand maximal stresses of up to 8 GPa and a maximal strain of 7% before breaking, making them suitable for stretchable electronic and optomechanical devices.

Single-walled carbon nanotubes functionalized by a series of dichlorocarbenes: DFT study

2016 ◽  
Vol 30 (08) ◽  
pp. 1650118 ◽  
Author(s):  
Igor K. Petrushenko ◽  
Konstantin B. Petrushenko
Keyword(s):  
Carbon Nanotubes ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Density Functional ◽  
Young's Modulus ◽  
Strong Dependence ◽  
Single Walled Carbon Nanotubes ◽  
Binding Energies ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

The structural and elastic properties of neutral and ionized dichlorocarbene (CCl2) functionalized single-walled carbon nanotubes (SWCNTs) were studied using density functional theory (DFT). The Young’s modulus of ionized pristine SWCNTs is found to decrease in comparison to that of neutral models. The interesting effect of increase in Young’s modulus values of ionized functionalized SWCNTs is observed. We ascribe this feature to the concurrent processes of the bond elongation on ionization and the local deformation on cycloaddition. The strong dependence of the elasticity modulus on the number of addends is also observed. However, the CCl2-attached SWCNTs in their neutral and ionized forms remain strong enough to be suitable for the reinforcement of composites. In contrast to the elastic properties, the binding energies do not change significantly, irrespective of CCl2 coverage.

Fibers of Bamboo and Hem Palm Tree

2001 ◽  
Vol 702 ◽  
Author(s):  
Shigeyasu Amada
Keyword(s):  
Young’S Modulus ◽  
Elastic Properties ◽  
Volume Fraction ◽  
Young's Modulus ◽  
Simple Procedure ◽  
High Strength ◽  
Tensile Tests ◽  
Palm Tree ◽  
Bamboo Fibers ◽  
The One

ABSTRACTBamboo is a typical composite material which is axially reinforced by very strong fibers. So that, the fibers play an important role for the bamboo structure. The elastic properties of the bamboo culm have been measured only by tensile test so far, which needs a large specimen. Recently ultra-sonic technique, which has a simple procedure and uses a small specimen, has been applied to woods as well as metals. This report reviews about the elastic properties of bamboo and Hemp palm fibers. The Young's modulus and Poisson's ratio of the bamboo fibers are measured by ultra-sonic method with a transmitting wave. On the other hand, the strength of the bamboo and Hemp palm fibers are measured by the tensile tests. Using the volume fraction of fibers in the specimen and mixture principle, the Young's modulus and strength of the fibers and parenchyma were obtained. The fiber has a high strength up to 1GPa and an strong anisotropic property because its axial Young's modulus has 7 times higher than the one in the transverse direction.

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