scholarly journals Broadband-excitation-based mechanical spectroscopy of highly viscous tissue-mimicking phantoms

2021 ◽  
Author(s):  
Magdalena Urbanska ◽  
Sylwia Kolenderska ◽  
Sophia Rodrigues ◽  
Sachin Thakur ◽  
Frederique Vanholsbeeck
Keyword(s):  
Mechanical Spectroscopy

scholarly journals Influence of Nb on Ti diffusion in γ-TiAl intermetallics studied by mechanical spectroscopy

2021 ◽  
Vol 867 ◽  
pp. 158880
Author(s):  
J. Ibáñez-Pérez ◽  
M.L. Nó ◽  
M. Oehring ◽  
H. Clemens ◽  
J.M. San Juan
Keyword(s):  
Mechanical Spectroscopy ◽  
Tial Intermetallics

Mechanical Spectroscopy Study on the Light Soaking Effect on Hydrogenated Amorphous Silicon

2012 ◽  
Vol 184 ◽  
pp. 416-421 ◽  
Author(s):  
H. Mizubayashi ◽  
I. Sakata ◽  
H. Tanimoto
Keyword(s):  
Internal Friction ◽  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Wide Distribution ◽  
Activation Energies ◽  
Mechanical Spectroscopy ◽  
Induced Changes ◽  
Mild Temperature ◽  
Hydrogenated Amorphous

For hydrogenated amorphous silicon (a-Si:H) films deposited at temperatures between 423 K and 623 K (a-Si:H423Kand so on), the light-induced changes in the internal friction between 80 K and 400 K were studied. The internal friction is associated with H2motion in microvoid networks, and shows the mild temperature dependence between about 80 K and 300 K (Q-180-300K) and the almost linear increase above 300 K (Q-1>300K). BothQ-180-300KandQ-1>300Kdecrease with increasing the deposition temperature, and show the mild temperature dependence ina-Si:H623K. The white light soaking with 100 mW/cm2(WLS100and so on) below 300 K caused a change inQ-180-300Kand no changes inQ-1>300K, respectively, and the light-induced changes inQ-180-300Krecovered after annealing at 423 K. The wide distribution of activation energies for H2motions between microvoids indicate that most of neighboring microvoids are connected through windows, i.e., the microvoid networks are existing ina-Si:H, and the spatially loose or solid structures are responsible for the low or high activation energies for the H2motion between microvoids, respectively. Furthermore, the light-induced hydrogen evolution (LIHE) was observed for WLS200to WLS400in a vacuum between 400 and 500 K, resulting in the disappearance of the internal friction due to the H2motion in the microvoid network.

High-Temperature Mechanical Relaxation due to Dislocation Motion inside Dislocation Networks

2008 ◽  
Vol 137 ◽  
pp. 21-28 ◽  
Author(s):  
Andre Rivière ◽  
Michel Gerland ◽  
Veronique Pelosin
Keyword(s):  
Internal Friction ◽  
Relaxation Effect ◽  
Dislocation Motion ◽  
Relaxation Peak ◽  
Mechanical Relaxation ◽  
In Situ Tem ◽  
Mechanical Spectroscopy ◽  
Internal Friction Peak ◽  
First Case ◽  
Dislocation Walls

Internal friction peaks observed in single or polycrystals are clearly due to a dislocation relaxation mechanism. Because a sample observed by transmission electron microscopy (TEM) often exhibits in the same time various dislocation microstructures (isolated dislocations, dislocation walls, etc.) it is very difficult to connect the observed relaxation peak with a particular dislocation microstructure. Using isothermal mechanical spectroscopy (IMS), it is easier to compare, for instance, the evolution of a relaxation peak with measurement temperature to the microstructural evolution observed by in-situ TEM at the same temperatures. IMS was used to study a relaxation peak in a 5N aluminium single crystal firstly 1% cold worked and then annealed at various temperatures. TEM experiments performed in the same material at various temperatures equal to the temperatures used for the damping experiments made possible to link this internal friction peak with a relaxation effect occurring inside dislocation walls. In two other experiments in a 4N aluminium polycrystal and in a metal matrix composite with SiC whiskers, it is shown that the observed relaxation peaks are connected to the motion of dislocations inside polygonization boundaries in the first case and in dislocation pile-ups around each whisker in the second one. Theoretical models proposed to explain such relaxation peaks due to a dislocation motion inside a dislocation wall or network are discussed.

Characterization of heterogeneity in concrete and cement by mechanical spectroscopy

2003 ◽  
Vol 33 (2) ◽  
pp. 241-244
Author(s):  
Fredy R. Zypman ◽  
Claudio Guerra-Vela
Keyword(s):  
Mechanical Spectroscopy

Mechanical Spectroscopy Investigation of Liquid Pb-Bi Alloys

2012 ◽  
Vol 184 ◽  
pp. 434-439 ◽  
Author(s):  
Roberto Montanari ◽  
Alessandra Varone
Keyword(s):  
Distribution Functions ◽  
X Ray Diffraction ◽  
Mechanical Spectroscopy ◽  
X Ray ◽  
Neutron Spallation Source ◽  
Driven System ◽  
Spallation Source ◽  
Accelerator Driven System ◽  
The Mean ◽  
Diffraction Patterns

Liquid Pb–Bi eutectic alloy has been selected as coolant and neutron spallation source for the development of MYRRHA, an accelerator driven system. The alloy has been characterized in liquid state from melting (125 °C) to 650 °C by mechanical spectroscopy. Experiments have been carried out using hollow reeds of austenitic stainless steel filled with the Pb-Bi alloy and sealed at the extremities. From 350 °C to 520 °C modulus shows a remarkable drop accompanied by a broad internal friction maximum. In the same temperature range radial distribution functions, determined from X-ray diffraction patterns, evidenced variations of the mean distance between the 1st nearest neighbour atoms. The anelastic phenomena have been attributed to a structural re-arrangement of liquid metal. For comparison, other alloys of the Pb-Bi system with hypo-eutectic composition have been investigated.

scholarly journals Influence of Pretreatment Factors on Two-dimensional Correlation Dynamic Mechanical Spectroscopy Features

2013 ◽  
Vol 48 ◽  
pp. 132-139 ◽  
Author(s):  
Xiaoan Wang ◽  
Kewei Xiang ◽  
Dian Zhang ◽  
Jinrong Wu ◽  
Guangsu Huang
Keyword(s):  
Two Dimensional ◽  
Mechanical Spectroscopy ◽  
Dynamic Mechanical Spectroscopy ◽  
Dynamic Mechanical

Diffusion Phenomena of the Oxygen and Nitrogen in Niobium by Mechanical Spectroscopy

2010 ◽  
Vol 297-301 ◽  
pp. 1346-1353
Author(s):  
Odila Florêncio ◽  
Paulo Sergio Silva ◽  
Carlos Roberto Grandini
Keyword(s):  
Diffusion Coefficients ◽  
Short Range ◽  
Annealed Sample ◽  
Relaxation Processes ◽  
Torsion Pendulum ◽  
Mechanical Spectroscopy ◽  
Interstitial Diffusion ◽  
Relaxation Parameters ◽  
Low Concentrations ◽  
Diffusion Phenomena

The short-range diffusion phenomenon (Snoek Effect) was investigated by mechanical spectroscopy measurements between 300 K and 650 K, in a polycrystalline niobium sample, containing oxygen and nitrogen, using a torsion pendulum. Experimental spectra of anelastic relaxation were obtained under three conditions: as-received sample; annealed sample and subsequently annealed in an oxygen atmosphere for three hours at 1170 K in partial pressure of 5x10-5mbar. The experimental spectra obtained were decomposed in elementary Debye peaks and the anelastic relaxation processes were identified. With anelastic relaxation parameters and the lattice parameters, the interstitial diffusion coefficients of the oxygen and nitrogen in niobium were calculated for each kind of preferential occupation (octahedral and tetrahedral). The results were compared with the literature data, and confirmed that the best adjustment is for the preferential occupation octahedral model for low concentrations of interstitial solutes, but at higher concentration of oxygen were observed deviations of experimental data for the interstitial diffusion coefficients of oxygen in niobium when compared with the literature data, this could be related to the possible occurrence of a double occupation of interstitial sites in the niobium lattice by oxygen interstitials.

Investigation of the structure and properties of quartz in the α-β transition range by neutron diffraction and mechanical spectroscopy

2007 ◽  
Vol 52 (3) ◽  
pp. 428-435 ◽  
Author(s):  
A. N. Nikitin ◽  
G. V. Markova ◽  
A. M. Balagurov ◽  
R. N. Vasin ◽  
O. V. Alekseeva
Keyword(s):  
Neutron Diffraction ◽  
Structure And Properties ◽  
Mechanical Spectroscopy ◽  
Transition Range

Analysis of Microstructural Changes with Temperature of Thermally Sprayed WC-Co Coatings by Mechanical Spectroscopy

2012 ◽  
Vol 184 ◽  
pp. 313-318 ◽  
Author(s):  
Daniele Mari ◽  
L.M. Berger ◽  
S. Stahr
Keyword(s):  
Elastic Modulus ◽  
Sudden Increase ◽  
X Ray Diffraction ◽  
Mechanical Spectroscopy ◽  
Hvof Spraying ◽  
Mechanical Parts ◽  
Spark Erosion ◽  
Temperature Scanning ◽  
First Time ◽  
Thermally Sprayed

Thermally sprayed hardmetal coatings can be used to improve the wear or fatigue resistance of mechanical parts. Depending on the deposition conditions, their microstructure and phase composition are out of equilibrium at different levels due to the extreme heating/cooling rates. In the present study, the changes that occur with temperature variation are monitored by mechanical spectroscopy. Requirements to specimen of mechanical spectroscopy created the need to prepare WC-17%Co coatings of 1.2 mm thickness by high velocity oxy-fuel (HVOF) spraying. The coatings, separated from the substrate by spark erosion, were tested in a forced torsion pendulum between room temperature and 1570 K at a temperature scanning rate of 1K/min. The mechanical loss spectrum shows different features. At 800 K, a maximum M1 is observed in coincidence with a sudden increase of the elastic modulus. The change of the elastic modulus is due to a densification of the material possibly related to cobalt recrystallization. A relaxation peak located at about 1100 K is typically found in WC-Co hardmetals. It is attributed to the movement of dislocations in the cobalt phase. A sharp peak is observed at 1510 K on heating and at 1410 K on cooling. Such peak is due to the reversible transition from W3Co3C at high temperature to W6Co6C at low temperature as proven by X-ray diffraction. The reversibility of such transformation was observed for the first time.

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