Effect of Temperature on Elasticity of Silicon Nanowires

2011 ◽  
Vol 483 ◽  
pp. 526-531
Author(s):  
Jing Wang
Keyword(s):  
Young’S Modulus ◽  
Silicon Nanowires ◽  
Strain Energy ◽  
Young's Modulus ◽  
Silicon Nanowire ◽  
Negative Temperature ◽  
Lattice Parameter ◽  
Mechanical Analysis ◽  
Effect Of Temperature ◽  
Continuum Approach

A semi-continuum approach is developed for mechanical analysis of a silicon nanowire, which captures the atomistic physics and retains the efficiency of continuum models. By using the Keating model, the strain energy of the nanowire required in the semi-continuum approach is obtained. Young’s modulus of the silicon (001) nanowire along [100] direction is obtained by the developed semi-continuum approach. Young’s modulus decreases dramatically as the size of a silicon nanowire width and thickness scaling down, especially at several nanometers, which is different from its bulk counterpart. The semi-continuum approach is extended to perform a mechanical analysis of the silicon nanowire at finite temperature. Taking into account the variations of the lattice parameter and the bond length with the temperature, the strain energy of the system is computed by using Keating anharmonic model. The dependence of young’s modulus of the nanowire on temperature is predicted, and it exhibits a negative temperature coefficient.

Size-Dependence on Load Properties of a Silicon Nanobeam

2012 ◽  
Vol 503 ◽  
pp. 406-410
Author(s):  
Jing Wang ◽  
Hong Yan Zhang
Keyword(s):  
Young’S Modulus ◽  
Size Dependence ◽  
Young's Modulus ◽  
Mechanical Analysis ◽  
Continuum Models ◽  
Continuum Approach ◽  
Scaling Down

A semi-continuum approach is developed for mechanical analysis of a silicon nanobeam, which captures the atomistic physics and retains the efficiency of continuum models. Young’s modulus of the silicon (001) nanobeam along [100] direction is obtained by the developed semi-continuum approach, which decreases dramatically as the size of a silicon nanobeam width and thickness scaling down. Taking into account the variations of Young’s modulus at different size, the load properties of the nanobeam is computed. The model predicts the deflection of the nanobeam is size-dependence. Introduction

Effect of temperature on properties of aluminum/single-walled carbon nanotube nanocomposite by molecular dynamics simulation

2019 ◽  
Vol 234 (2) ◽  
pp. 635-642 ◽  
Author(s):  
Mohsen Motamedi ◽  
AH Naghdi ◽  
SK Jalali
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Molecular Dynamics Simulation ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Strain Curve ◽  
Dynamics Simulation ◽  
Effect Of Temperature ◽  
Metal Composite

Composite materials have become popular because of high mechanical properties and lightweight. Aluminum/carbon nanotube is one of the most important metal composite. In this research, mechanical properties of aluminum/carbon nanotube composite were obtained using molecular dynamics simulation. Then, effect of temperature on stress–strain curve of composite was studied. The results showed by increasing temperature, the Young’s modulus of composite was decreased. More specifically increasing the temperature from 150 K to 620 K, decrease the Young’s modulus to 11.7%. The ultimate stress of composite also decreased by increasing the temperature. A continuum model of composite was presented using finite element method. The results showed the role of carbon nanotube on strengthening of composite.

Effective Young’s Modulus of Syntactic Foams with Hollow Glass Microspheres

2010 ◽  
Vol 29-32 ◽  
pp. 607-612 ◽  
Author(s):  
Chang Jun He ◽  
Hui Jian Li ◽  
Wei Yu ◽  
Xi Liang ◽  
Hai Yan Peng
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Mechanical Analysis ◽  
Particulate Composites ◽  
Syntactic Foams ◽  
Glass Microspheres ◽  
Hollow Glass Microspheres ◽  
Hollow Glass ◽  
Young’S Moduli ◽  
Effective Young's Moduli

. The Young’s modulus of syntactic foams were studied both the experiment and the theory. The compressive test and dynamic mechanical analysis were progressed for a few of specimens, which were made of the syntactic foams with the epoxy resin and hollow glass microspheres (HGMs). the equations for Young’s modulus of concentrated particulate composites were derived using a differential scheme of an infinitely dilute system, and were employed to prediction the Young’s modulus of syntactic foams. The computed effective Young’s moduli were compared with the experimental results, the prediction values were between the lower and upper bounds of the experimental data, and the prediction model was acceptable and can estimate the Young’s modulus of syntactic foams.

Effect of yttrium addition on lattice parameter, Young's modulus and vacancy of magnesium

2011 ◽  
Vol 528 (4-5) ◽  
pp. 2106-2109 ◽  
Author(s):  
Qiuming Peng ◽  
Jian Meng ◽  
Yangde Li ◽  
Yuangding Huang ◽  
Norbert Hort
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Lattice Parameter ◽  
Yttrium Addition

Longitudinal vibration wave in the composite elastic metamaterials containing Bragg structure and local resonator

2020 ◽  
Vol 34 (26) ◽  
pp. 2050232
Author(s):  
Xiaofei Lei ◽  
Peng Chen ◽  
Heping Hou ◽  
Shanhui Liu ◽  
Peng Liu
Keyword(s):  
Mathematical Model ◽  
Young’S Modulus ◽  
Transmission Spectrum ◽  
Strain Energy ◽  
Young's Modulus ◽  
Dynamic Properties ◽  
Longitudinal Vibration ◽  
Total Width ◽  
Bragg Structure ◽  
Vibration Wave

In this paper, a novel composite acoustical hyperstructure of Bragg structure with local resonator is investigated theoretically for discussing the scattering performance of longitudinal vibration wave, its bandgaps are calculated using the established mathematical model. For confirming the veritable existence of bandgap and verifying the correctness of established mathematical model, the transmission spectrum of composite acoustical hyperstructure is also studied using finite-element method, and comparing the vibration transmission spectrum with bandgaps, the results indicate that the established theoretical model can correctly predict longitudinal wave bandgaps. Moreover, the bandgaps and modes shapes are calculated and compared with an unalloyed Bragg structure for probing the dispersion mechanics of composite acoustical hyperstructure, it turned out that local resonator can add one bandgap at the base of Bragg structure and the total bandgaps can be broadened. Further, for discussing the effect of spring of local resonator on bandgaps, bandgap of local resonator with different spring is calculated, the results showed that the total width of BG is larger when Young’s modulus is 1E and 16E, the total width are 772.48 and 774.30 Hz, respectively; as Young’s modulus is 0.5E and 2E, the width of BG are lower, 753.79 and 754.23 Hz, respectively. In view of longitudinal vibration wave inducing structural distortion and vibration energy conversion, the dynamic properties of composite acoustical hyperstructure are studied via strain energy density, the results indicate that reaction formation of local resonator can dissipate strain energy, when the local resonator is not activated (or waveless along with Bragg structure), un-dissipation strain energy.

Elastic Strain Energy of a Nanowire in Three-Point Bending Test with the Consideration of Surface Effects

2011 ◽  
Vol 268-270 ◽  
pp. 67-71
Author(s):  
Xian Wei Zeng ◽  
Jia Quan Deng
Keyword(s):  
Young’S Modulus ◽  
Elastic Strain ◽  
Strain Energy ◽  
Young's Modulus ◽  
Elastic Strain Energy ◽  
Theoretical Models ◽  
Bending Test ◽  
Three Point Bending ◽  
Force Microscopy ◽  
Atomic Force

Three-point bending tests of nanowires with Contact atomic force microscopy reveal that the Young’s modulus of a nanowire is size-dependent. The modulus changes with the diameter of a nanowire. This size dependency can be explained within the framework of classical continuum mechanics by including the effects of surface stress. In this study, an analytical solution has been derived for the elastic strain energy of a nanowire with both ends clamped and contacted by an AFM tip at its midpoint. Different from previous theoretical models, the present model can handle the case of large deflection, where the displacement of the nanowire is in the same order of the diameter. Based on the equivalence of elastic strain energy, the apparent Young’s modulus of a nanowire is expressed as a function of the elastic modulus of the bulk and that of the surface, and the dimensions of a nanowire.

Mechanical Properties of Nanoparticle Hydroxyapatite/gelatin Constructs

2007 ◽  
Vol 1063 ◽  
Author(s):  
Steven Fox ◽  
Inessa Stanishevskaya ◽  
Shafiul Chowdhury ◽  
Shane Catledge ◽  
Andrei Stanishevsky
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Bending Strength ◽  
Young's Modulus ◽  
Bone Microarchitecture ◽  
Bone Substitutes ◽  
Mechanical Analysis ◽  
Model Material ◽  
Bending Modulus ◽  
Nanoparticle Dispersions

ABSTRACTBone consists of up to 70% mostly nanocrystalline hydroxyapatite (HA), and the rest is mostly collagen. One can suggest that synthetic nanoHA/collagen composites could potentially be the closest materials to resemble the bone microarchitecture and prepare resorbable bone substitutes and scaffolds. However, the data on the mechanical properties and property/structure relationships of HA/collagen composites are still scarce. It can be explained, in part, by the high cost of collagen and substantial amounts of materials needed for many tests. However, gelatin is cheap, has many properties similar to collagen, and can be used as a model material for the mechanical testing of HA-based composites. In this study, we report the results of an investigation of some mechanical properties of HA/gelatin composites with 0 to 80% HA nanoparticle (size 15-60 nm) loading by weight. The HA nanoparticle dispersions were mixed with gelatin in trifluoroethanol or in water in different ratios and placed in Teflon molds to produce the sheets with the thickness in the range of 0.4 – 1.0 mm. Nanoindentation technique was used to determine the Young's modulus and hardness. Bending tests were performed using dynamic mechanical analysis with the amplitudes in the 1 – 50 micron range at 1 Hz. The values of Young's modulus (1 – 20 GPa), hardness (70 – 500 MPa) and bending modulus (0.3 – 2.4 GPa) were obtained. The highest values of the Young's modulus and hardness of these composite materials were achieved for 40% – 60% HA content by weight, which was close to the values for similar HA/collagen composites. However, the maximum bending strength was observed for 20 – 35% HA content. We discuss further the observed trends of the mechanical properties and their dependence on other factors such as the test conditions, sample geometry, and HA particle size.

Structure, Microstructure, and Selected Mechanical Properties of Ti-Zr-Mo Alloys for Biomedical Applications

2014 ◽  
Vol 922 ◽  
pp. 75-80 ◽  
Author(s):  
Diego Rafael Nespeque Correa ◽  
Pedro Akira Bazaglia Kuroda ◽  
Carlos Roberto Grandini
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Biomedical Applications ◽  
Biomedical Application ◽  
Young's Modulus ◽  
Microstructural Analysis ◽  
Melting Furnace ◽  
High Hardness ◽  
Mechanical Analysis ◽  
Β Phase

New titanium alloys for biomedical applications have been developed primarily with the addition of Nb, Ta, Mo, and Zr, because those elements stabilize the β phase and they don’t cause cytotoxicity in the organism. The objective of this paper is to analyze the effect of molybdenum on the structure, microstructure, and selected mechanical properties of Ti-15Zr-xMo (x = 5, 10, 15, and 20 wt%) alloys. The samples were produced in an arc-melting furnace with inert argon atmosphere, and they were hot-rolled and homogenized. The samples were characterized using chemical, structural, and microstructural analysis. The mechanical analysis was made using Vickers microhardness and Young’s modulus measurements. The compositions of the alloys were sensitive to the molybdenum concentration, indicating the presence of α’+α”+β phases in the Ti-15Zr-5Mo alloy, α”+β in the Ti-15Zr-10Mo alloy, and β phase in the Ti-15Zr-15Mo and Ti-15Zr-20Mo alloys. The mechanical properties showed favorable values for biomedical application in the alloys presenting high hardness and low Young’s modulus compared with CP-Ti.

Influence of Defects on the Young's Modulus of [110] Silicon Nanowires with Different Cross Sections

2015 ◽  
Vol 645-646 ◽  
pp. 151-156
Author(s):  
Fang Gu ◽  
Jia Hong Zhang ◽  
Min Li ◽  
Lin Yan Liu ◽  
Jing Su
Keyword(s):  
Young’S Modulus ◽  
Cross Sections ◽  
Silicon Nanowires ◽  
Surface Defects ◽  
Young's Modulus ◽  
High Surface ◽  
Surface Effects ◽  
Native Oxide ◽  
Native Oxide Layer ◽  
Induced Defects

The size dependence becomes more significant as the devices scale down from micro-to nanodimensions, which is generally attributed to surface effects due to the very high surface-to-bulk ratios in nanoscale structures. However, significant discrepancies between experimental measurements and computational studies indicate that there could be other influences besides surface effects, such as the influences of native oxide layer, fabrication-induced defects and boundary conditions. In this paper, our purpose is to investigate mainly the influence of fabrication-induced defects on the elasticity of [110] silicon nanowires (SiNWs) with different cross sections. We accomplish this by using the molecular dynamics (MD) simulation. Our MD results show that the H-passivated [110] SiNWs without surface defects is slightly elastically softer than bulk, which is in good agreement with other literature MD values. However, the effective Young’s modulus of SiNWs with surface defects can significantly decreases as the defects increase. This softening behavior of [110] SiNWs is severe, which indicates the importance of surface defects. It is noted that the influence of defects on the Young's Modulus of SiNWs strongly depended on the distribution and morphology of defects as well as the cross-sectional shapes of SiNWs. It is observed that the influence of defects on square SiNWs is significantly different from those of hexagonal and triangle SiNWs. Our work reveals that fabrication-induced surface defects could be one of the important origins of the reduced effective Young’s modulus experimentally observed in ultra-thin SiNWs. Therefore, the effect of defects on the characterization of the mechanical properties of nanowire must be carefully considered.

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