Influence of Surface Effect on the Equivalent Properties of Nanoporous Materials with Elastic Waves

2017 ◽

Vol 84 (6) ◽

Cited By ~ 1

Author(s):

Yin Yao ◽

Yazheng Yang ◽

Shaohua Chen

Keyword(s):

Energy Density ◽

Surface Energy ◽

Volume Fraction ◽

Surface Effect ◽

Compressive Strain ◽

Nanoporous Materials ◽

Surface Relaxation ◽

Surface Energy Density ◽

Closed Form Solutions ◽

Size Dependent

The size effect of nanoporous materials is generally believed to be caused by the large ratio of surface area to volume, so that it is also called surface effect. Based on a recently developed elastic theory, in which the surface effect of nanomaterials is characterized by the surface energy density, combined with two micromechanical models of composite materials, the surface effect of nanoporous materials is investigated. Closed-form solutions of both the effective bulk modulus and the effective shear one of nanoporous materials are achieved, which are related to the surface energy density of corresponding bulk materials and the surface relaxation parameter of nanomaterials, rather than the surface elastic constants in previous theories. An important finding is that the enhancement of mechanical properties of nanoporous materials mainly results from the compressive strain induced by nanovoid's surface relaxation. With a fixed volume fraction of nanovoids, the smaller the void size, the harder the nanoporous material will be. The results in this paper should give some insights for the design of nanodevices with advanced porous materials or structures.

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Diffractions of Elastic Waves and Stress Concentration Near a Cylindrical Nano-Inclusion Incorporating Surface Effect

Journal of Vibration and Acoustics ◽

10.1115/1.4000479 ◽

2009 ◽

Vol 131 (6) ◽

Cited By ~ 30

Author(s):

Y. Ru ◽

G. F. Wang ◽

T. J. Wang

Keyword(s):

Stress Concentration ◽

Elastic Waves ◽

Surface Effect ◽

Potential Method ◽

P Wave ◽

Compressional Waves ◽

Displacement Potential ◽

Elastic Fields ◽

P And Sv Waves ◽

Incident Waves

The diffractions of plane compressional waves (P-wave) and shear waves (SV-wave) by a cylindrical nano-inclusion are investigated in this paper. To account for the surface/interface effect at nanoscale, the surface/interface elasticity theory is adopted in the analysis. Using the displacement potential method, we obtain the solutions for the elastic fields induced by incident P- and SV-waves near a cylindrical nano-inclusion. The results show that surface/interface has a significant effect on the diffractions of elastic waves as the radius of the inclusion shrinks to nanoscale. For incident waves with different frequencies, the effects of interfacial properties on the dynamic stress concentration around the nano-inclusion are discussed in detail.

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Surface Effect on Diffractions of Elastic Waves and Stress Concentration near a Cluster of Cylindrical Nanoholes Arranged as Quadrate Shape

Advances in Materials Science and Engineering ◽

10.1155/2015/134975 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Ru Yan

Keyword(s):

Stress Concentration ◽

Multiple Scattering ◽

Elastic Waves ◽

Surface Effect ◽

Surface Elasticity ◽

Expansion Method ◽

Potential Method ◽

P Wave ◽

Displacement Potential ◽

P And Sv Waves

We consider the multiple scattering of elastic waves (P-wave and SV-wave) by a cluster of nanosized cylindrical holes arranged as quadrate shape. When the radius of the holes shrinks to nanometers, the surface elasticity theory is adopted in analysis. Using the displacement potential method and wave functions expansion method, we obtain that the multiple scattering fields induced by incident P- and SV-waves around the holes are derived. The dynamic stress concentration around the holes is calculated to illustrate the effect of surface effects on the multiple scattering of P- and SV-waves.

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Effect of Surface Energy on the Size-Dependent Yield Criterion of Nanoporous Materials under Complex Stress States

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.121-126.15 ◽

2011 ◽

Vol 121-126 ◽

pp. 15-19

Author(s):

Liu Juan Zhu ◽

Wen Zhong Cai ◽

Shan Tung Tu

Keyword(s):

Surface Energy ◽

Nanostructured Materials ◽

Surface Effect ◽

Yield Criterion ◽

Complex Stress ◽

Nanoporous Materials ◽

Octahedral Plane ◽

Size Dependent ◽

Stress States ◽

Effect Of Surface

Within a micromechanical framework, the effect of surface energy is taken into account to explore the size-dependent yield criterion of nanoporous materials under complex stress states. A theoretical picture of the yield behavior on an octahedral plane is illustrated as functions of the surface properties and void size. The prominent size dependence of the yield criterion of nanoporous materials highlights the importance of the surface effect in analyzing the strength of nanostructured materials. The results demonstrate a fundamental framework to extend continuum strength theories to the nanoscale with substantial surface effect, which may be useful for evaluating the mechanical integrity of nanostructured materials.

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Remarks on nonlinear elastic waves with null conditions

ESAIM Control Optimisation and Calculus of Variations ◽

10.1051/cocv/2020039 ◽

2020 ◽

Vol 26 ◽

pp. 121

Author(s):

Dongbing Zha ◽

Weimin Peng

Keyword(s):

Initial Data ◽

Global Existence ◽

Elastic Waves ◽

Wave Equations ◽

Alternative Proof ◽

Classical Solutions ◽

Small Initial Data ◽

Hyperelastic Materials ◽

Variational Structure ◽

Nonlinear Elastic

For the Cauchy problem of nonlinear elastic wave equations for 3D isotropic, homogeneous and hyperelastic materials with null conditions, global existence of classical solutions with small initial data was proved in R. Agemi (Invent. Math. 142 (2000) 225–250) and T. C. Sideris (Ann. Math. 151 (2000) 849–874) independently. In this paper, we will give some remarks and an alternative proof for it. First, we give the explicit variational structure of nonlinear elastic waves. Thus we can identify whether materials satisfy the null condition by checking the stored energy function directly. Furthermore, by some careful analyses on the nonlinear structure, we show that the Helmholtz projection, which is usually considered to be ill-suited for nonlinear analysis, can be in fact used to show the global existence result. We also improve the amount of Sobolev regularity of initial data, which seems optimal in the framework of classical solutions.

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THEORY OF THE ATTENUATION OF ELASTIC WAVES IN INHOMOGENEOUS SOLIDS

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1981632 ◽

1981 ◽

Vol 42 (C6) ◽

pp. C6-102-C6-104

Author(s):

P. G. Klemens

Keyword(s):

Elastic Waves

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The Effect of Pentosan Polysulphate (SP54) on the Fibrinolytic Enzyme System - A Human Volunteer and Experimental Animal Study

Thrombosis and Haemostasis ◽

10.1055/s-0038-1660143 ◽

1985 ◽

Vol 54 (04) ◽

pp. 833-837 ◽

Cited By ~ 7

Author(s):

N A Marsh ◽

P M Peyser ◽

L J Creighton ◽

M Mahmoud ◽

P J Gaffney

Keyword(s):

Plasminogen Activator ◽

Surface Effect ◽

Ex Vivo ◽

Vena Cava ◽

Tissue Type ◽

Similar Response ◽

Small Contribution ◽

Thrombosis Model ◽

Pentosan Polysulphate

SummaryPentosan polysulphate causes an increase in plasminogen activator activity in plasma both after oral ingestion and after subcutaneous injection. The effect is greatest after 3 h and has disappeared by 6 h. Repeat doses by mouth over 5 days elicit a similar response. The recorded increase in activity is due largely to the release of tissue-type plasminogen activator (tPA) from the endothelium according to the antigen assay although there could be a small contribution from Factor XH-related “intrinsic” fibrinolysis induced in vitro. SP54 enhances activity ex vivo by a non-specific surface effect, and this phenomenon may contribute the increased levels of activity seen in vitro. Administration of SP54 to animals elicits a similar increase in activator activity, the intramuscular route being slightly more effective. Results with an inferior vena cava thrombosis model in the rat suggest that pentosan polysulphate may induce a thrombolytic effect.

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