scholarly journals The Bakerian Lecture: On the viscosity or internal friction of air and other gases

1867 ◽  
Vol 15 ◽  
pp. 14-17 ◽  
Keyword(s):  
Internal Friction ◽  
The Other ◽  
Elastic Solids ◽  
Soft Solids

All bodies which are capable of having their form indefinitely altered, and which resist the change of form with a force depending on the rate of deformation, may be called Viscous Bodies. Taking tar or treacle as an instance in which both the change of form and the resistance opposed to it are easily observed, we may pass in one direction through the series of soft solids up to the materials commonly supposed to be most unyielding, such as glass and steel, and in the other direction through the series of liquids of various degrees of mobility id the gases, of which oxygen is the most viscous, and hydrogen the least. The viscosity of elastic solids has been investigated by M. F. Kohlrausch and Professor W. Thomson; that of gases by Professor Stokes, M. O. E. Meyer, and Mr. Graham.

Ground vibrations near dynamite blasts*

1939 ◽  
Vol 29 (3) ◽  
pp. 487-496
Author(s):  
L. Don Leet
Keyword(s):  
Internal Friction ◽  
Initial Energy ◽  
The Other ◽  
Ground Vibrations ◽  
Two Factors ◽  
Natural Decay

Summary In general, then, the concentrated energy at the source is actually divided among the principal wave types, which are there added together. Within very short distances, however, these wave types begin to separate because of their different velocities. There are thus two factors working to reduce the maximum shaking to which the ground is subjected. One is the natural decay of each wave with distance, as internal friction exhausts its original energy. The other, which is usually the dominating effect at short distances, is this stringing out of the wave types, each carrying its portion of the initial energy, until there is no longer any concentration where two or more types join forces to produce additive amplitudes.

scholarly journals Extreme cavity expansion in soft solids: Damage without fracture

2020 ◽  
Vol 6 (13) ◽  
pp. eaaz0418 ◽  
Author(s):  
Jin Young Kim ◽  
Zezhou Liu ◽  
Byung Mook Weon ◽  
Tal Cohen ◽  
Chung-Yuen Hui ◽  
...  
Keyword(s):  
Phase Separation ◽  
Brittle Materials ◽  
Damage Mechanism ◽  
Cavity Expansion ◽  
Small Scale ◽  
Elastic Solids ◽  
Ductile Metals ◽  
Scale Free ◽  
Soft Solids ◽  
Bond Breakage

Cavitation is a common damage mechanism in soft solids. Here, we study this using a phase separation technique in stretched, elastic solids to controllably nucleate and grow small cavities by several orders of magnitude. The ability to make stable cavities of different sizes, as well as the huge range of accessible strains, allows us to systematically study the early stages of cavity expansion. Cavities grow in a scale-free manner, accompanied by irreversible bond breakage that is distributed around the growing cavity rather than being localized to a crack tip. Furthermore, cavities appear to grow at constant driving pressure. This has strong analogies with the plasticity that occurs surrounding a growing void in ductile metals. In particular, we find that, although elastomers are normally considered as brittle materials, small-scale cavity expansion is more like a ductile process. Our results have broad implications for understanding and controlling failure in soft solids.

Oxygen Vacancy Relaxation in Ca3Co4O9+δ Ceramics

2012 ◽  
Vol 184 ◽  
pp. 98-103 ◽  
Author(s):  
G.C. Lin ◽  
H. Liu ◽  
J.X. Zhang
Keyword(s):  
Activation Energy ◽  
Internal Friction ◽  
Relaxation Process ◽  
Preexponential Factor ◽  
Mechanical Analysis ◽  
The Other ◽  
Mechanical Relaxation ◽  
Ceramic Powders ◽  
Oxygen Treatment ◽  
Pc Method

Ca3Co4O9+δceramic powders were synthesized by the polymerized complex (PC) method. The same Ca3Co4O9+δceramic bar were treated in turn with three different processes of oxygen treatment: with no treatment, with oxydol (H2O2) treatment, and with N2treatment. Dynamic mechanical analysis (DMA) was performed from 123 to 623 K at rate of 1 K/min while the measuring frequencies are 0.05, 0.1, 0.25, 0.5, 1, 2, and 5 Hz. Two internal friction peaks are observed: one at the temperature range from 360 to 400 K (a broad peak, peak 1) and the other at around 390 K (a sharp peak, peak 2). Peak 2 is in correspondence with sudden metal-semiconductor transition (MST) near 400 K. Peak 1 is a kind of internal friction relaxation peak. For the sample with H2O2treatment and with no treatment, the activation energyHare 1.24 eV and 1.04 eV, respectively, and the preexponential factor τ0are 2.54×10-17sec and 7.82×10-15sec, respectively. We speculate that the mechanical relaxation process occurs in the Ca2CoO3subsystem of Ca3Co4O9+δ. The relaxation process for sample with no treatment is associated with the migration of OVs clusters in Ca2CoO3subsystem, and the relaxation process for the sample with H2O2treatment is associated with the migration of isolated OVs in Ca2CoO3subsystem.

scholarly journals The effect of surface roughness on the adhesion of elastic solids

1975 ◽  
Vol 345 (1642) ◽  
pp. 327-342 ◽  
Keyword(s):  
Flat Surface ◽  
The Other ◽  
Contact Theory ◽  
Elastic Displacement ◽  
Radius Of Curvature ◽  
Statistical Average ◽  
Elastic Solids ◽  
Maximum Value ◽  
Effect Of Surface ◽  
Adhesive Forces

This paper describes a study of the adhesion between elastic solids and the effect of roughness in reducing the adhesion. The experiments were carried out between optically smooth rubber spheres and a hard smooth flat surface of Perspex which could be roughened to various degrees. The radius of the rubber spheres was varied by a factor of 8, their elastic modulus by a factor of 10, while the centre line average (c.l.a.)of the roughened Perspex surface was varied from 0.12 to 1.5 μm. The results show that c.l.a. roughnesses which are small compared with the overall deformation occurring at the region of the rubber-Perspex contact can produce an extremely large reduction in adhesion. The effect is more marked for rubbers of higher modulus. On the other hand the curvature of the sphere (over the range examined) has little influence. For this reason and because the analytical problem of a sphere on a rough flat is extremely complicated a theoretical analysis has been developed for the simpler case of a smooth flat in contact with a rough flat surface. As in Greenwood & Williamson (1966) the rough surface is modelled by asperities all of the same radius of curvature and with heights following a Gaussian distribution of standard deviation σ. The overall contact force is obtained by applying the contact theory of Johnson, Kendall & Roberts (1971) to each individual asperity. The theory predicts that the adhesion expressed as a fraction of the maximum value depends upon a single parameter, 1/Δ e ,which is the ratio between a and the elastic displacement δ C that the tip of an asperity can sustain before it pulls off from the other surface. The analysis shows that the adhesion parameter may also be regarded as representing the statistical average of a competition between the compressive forces exerted by the higher asperities trying to prize the surfaces apart and the adhesive forces between the lower asperities trying to hold the surfaces together. Although the theory is derived for two nominally plane surfaces it is found to fit the experimental results for a sphere on a flat reasonably well.

Toughness and Internal Friction of Weld Metal Welded by High-Current MAG Welding

2011 ◽  
Vol 328-330 ◽  
pp. 1077-1081
Author(s):  
An Xia Pan
Keyword(s):  
Internal Friction ◽  
Weld Metal ◽  
Acicular Ferrite ◽  
Impact Test ◽  
Optical Microscope ◽  
The Other ◽  
Mag Welding ◽  
Welding Parameters ◽  
High Current ◽  
Temperature Impact

Low-temperature impact test on four different kinds of weld metal welded by different technologies of high-current MAG welding was carried out in this paper. The results show that different materials and different welding parameters have different effect on impact energy. As the chemical analysis and observation from the optical microscope show that When welding material contains appropriate C, Si, Ti, fine acicular ferrite forms in it; on the contrary, crisp and thick bainite appears. Compares to acicular ferrite which has an Akv>27J at -27°C and better toughness, bainite has a poor toughness and an Akv<27J. The internal friction experiments show that there are two internal friction peaks - Snoek and SKK. The peak is clear when the microstructure is bainite, on the other side, the microstructure is acicular ferrite.

Analysis of Internal Friction Peaks in High Purity Molybdenum by a Viscoelastic Procedure Independent of the Relaxation Strength

2008 ◽  
Vol 137 ◽  
pp. 49-58
Author(s):  
C.L. Matteo ◽  
O.A. Lambri ◽  
G.I. Zelada-Lambri ◽  
P.A. Sorichetti ◽  
Jose Angel García
Keyword(s):  
Internal Friction ◽  
High Purity ◽  
The Other ◽  
Relaxation Processes ◽  
Relaxation Strength ◽  
Viscoelastic Analysis ◽  
Linear Viscoelastic ◽  
Damping Peak ◽  
And Diffusion ◽  
Diffusion Of Vacancies

In this work we present a novel procedure, involving linear viscoelastic analysis, to discriminate the two possible contributions of the observed damping peak which appears around 840 K – 1050 K in mechanically deformed high purity single-crystalline molybdenum. An interesting feature of the procedure is that, for low damping samples, it can efficiently resolve experimental peaks that result from the superposition of different processes independently of the ratio between their relaxation strengths. This allows us to confirm that two different relaxation processes appear in molybdenum in the temperature range about 0.3 Tm, one around 840 K, and the other one near 1050 K. These can be related to diffusion and to a coupled mechanism involving creation and diffusion of vacancies, respectively.

scholarly journals Faraday waves in soft elastic solids

2020 ◽  
Vol 476 (2241) ◽  
pp. 20200129
Author(s):  
Giulia Bevilacqua ◽  
Xingchen Shao ◽  
John R. Saylor ◽  
Joshua B. Bostwick ◽  
Pasquale Ciarletta
Keyword(s):  
Soft Matter ◽  
Theoretical Explanation ◽  
Subharmonic Resonance ◽  
Viscous Fluids ◽  
Faraday Waves ◽  
Elastic Solids ◽  
Soft Solids ◽  
Elastic Bodies ◽  
Faraday Instability ◽  
Elastic Slab

Recent experiments have observed the emergence of standing waves at the free surface of elastic bodies attached to a rigid oscillating substrate and subjected to critical values of forcing frequency and amplitude. This phenomenon, known as Faraday instability, is now well understood for viscous fluids but surprisingly eluded any theoretical explanation for soft solids. Here, we characterize Faraday waves in soft incompressible slabs using the Floquet theory to study the onset of harmonic and subharmonic resonance eigenmodes. We consider a ground state corresponding to a finite homogeneous deformation of the elastic slab. We transform the incremental boundary value problem into an algebraic eigenvalue problem characterized by the three dimensionless parameters, that characterize the interplay of gravity, capillary and elastic waves. Remarkably, we found that Faraday instability in soft solids is characterized by a harmonic resonance in the physical range of the material parameters. This seminal result is in contrast to the subharmonic resonance that is known to characterize viscous fluids, and opens the path for using Faraday waves for a precise and robust experimental method that is able to distinguish solid-like from fluid-like responses of soft matter at different scales.

Influence of temperature on the hydrothermal clay soils' shear strength of the Nizhne-Koshelevsky and Verkhne-Pauzhetsky thermal fields.

2021 ◽  
Author(s):  
Ruslan Kuznetsov ◽  
Mikhail Chernov ◽  
Victoria Krupskaya ◽  
Ruslan Khamidov
Keyword(s):  
Internal Friction ◽  
Double Layer ◽  
Electric Double Layer ◽  
Geothermal Field ◽  
The Other ◽  
Clay Soils ◽  
Clayey Soils ◽  
Clay Particles ◽  
Angle Of Internal Friction ◽  
Thermal Fields

&lt;p&gt;Nizhne-Koshelevskoe and Verkhne-Pauzhetskoe thermal fields are located in the south of Kamchatka, the first - within the Koshelevsky volcanic massif, the second - on the territory of the Pauzhetsky geothermal field. The first horizon from the surface in these fields is formed by clayey soils, that have been formed as a result of hydrothermal alteration of volcanic rocks. And in the natural conditions clayey soils are at temperatures reaching 100 &amp;#176;C.&lt;/p&gt;&lt;p&gt;Samples of undisturbed clay soils were taken within the thermal fields. The samples are characterized by a density of 1.29 - 1.42 g/cm&lt;sup&gt;3&lt;/sup&gt;, rather high values of the weight moisture (90-110%), and temperatures of 50 - 70 &amp;#176;C.&lt;/p&gt;&lt;p&gt;The samples are dominated by clay minerals: kaolinite and mixed-layer - kaolinite-smectite, their content is about 75%. The other 25% are microcline, cristobalite, anatase, gypsum, pyrite, marcasite, quartz and alunite.&lt;/p&gt;&lt;p&gt;For samples of undisturbed clay soils, direct shear tests were carried out at a temperature of 20 &amp;#176;C and at a temperatures of the samples close to their natural temperatures (50&amp;#8211;70 &amp;#176;C). Thus, the values of cohesion and the angle of internal friction of the samples were determined.&lt;/p&gt;&lt;p&gt;The obtained results can be interfered as follows: as a result of an increase in the temperature of clayey soils, the thickness of electric double layer on the surface of clay particles decreases. On the one hand, it leads to a decrease of cohesion value between the clay particles and the beginning of shear deformations at lower vertical loads. On the other hand, a smaller thickness of electric double layer brings particles closer to each other, which is the reason for an increasing angle of internal friction and shear resistance at higher vertical loads.&lt;/p&gt;

High Damping Performance of Hydrogenated Bulk Metallic Glasses

2006 ◽  
Vol 319 ◽  
pp. 133-138 ◽  
Author(s):  
H. Mizubayashi ◽  
K. Yamagishi ◽  
H. Tanimoto
Keyword(s):  
Internal Friction ◽  
Concentration Dependence ◽  
Metallic Glasses ◽  
Structural Relaxation ◽  
High Strength ◽  
Peak Height ◽  
Point Of View ◽  
The Other ◽  
Internal Friction Peak ◽  
Material Parameters

Hydrogenated Zr-Cu-base metallic glasses (MGs) are the potential high-damping and high-strength materials. On the other hand, the knowledge on the material parameters which govern the peak temperature, Tp, and the peak height, Q-1 p, of the hydrogen internal friction peak (HIFP) remains poor. In order to pursue this issue, the hydrogen concentration dependence of Tp and Q-1 p in the Zr-Cu-base MGs were investigated in the point of view of the hydrogen induced structural relaxation (HISR). It is found that the Tp vs. CH data and the Q-1 p vs. CH data are well fitted by the relationships of Tp = Tp exp(-CH/τH) +Tp,0 and Qp -1 ∝ ln(CH/τH), respectively, for various Zr-Cu-base MGs including bulk MGs, Zr55Cu30Al10Ni5 and Zr60Cu30Al10. That is, the observed relationship between Tp and CH is mainly governed by HISR. It is suggested that Tp,0 in Zr-Cu-base MGs is the highest among various MGs resulting in the highest Tp in Zr-Cu-base MGs. In other words, the control of Tp,0 is the key issue to find the high-Tp MGs.

Vibration of Elastic Structures With Cracks

1993 ◽  
Vol 60 (2) ◽  
pp. 414-421 ◽  
Author(s):  
I. Y. Shen
Keyword(s):  
Integral Equation ◽  
Fredholm Integral Equation ◽  
The Other ◽  
Internal Crack ◽  
Two Dimensional ◽  
Antiplane Strain ◽  
Elastic Solids ◽  
Helmholtz Operator ◽  
Crack Configuration ◽  
Analytical Algorithm

An analytical algorithm is proposed to represent eigensolutions [λm2, ψm(r)]m=1∞ of an imperfect structure C containing cracks in terms of crack configuration σc and eigensolutions [ωn2, φn(r)]n=1∞ of a perfect structured without P the cracks. To illustrate this algorithm on mechanical systems governed by the two-dimensional Helmholtz operator, the Green’s identity and Green’sfunction of P are used to represent ψm(r) in terms of an infinite series of φn(r). Substitution of the ψn(r) representation into the Kamke quotient of C and stationarity of the quotient result in a matrix Fredholm integral equation. The eigensolutions of the Fredholm integral equation then predict λm2 and ψm(r) of C. Finally, eigensolutions of two rectangular elastic solids under antiplane strain vibration, one with a boundary crack and the other with an oblique internal crack, are calculated numerically.

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