Ultrasonic Investigation of the Effect of Volume Fraction on the Clustering Structures of Magneto-Rheological Fluids

2010 ◽  
Vol 670 ◽  
pp. 198-206 ◽  
Author(s):  
M.A. Bramantya ◽  
H. Takuma ◽  
J. Kuroiwa ◽  
T. Sawada
Keyword(s):  
Magnetic Field ◽  
Wave Propagation ◽  
External Magnetic Field ◽  
Ultrasonic Wave ◽  
Propagation Velocity ◽  
Magnetic Particles ◽  
Volume Fraction ◽  
Wave Propagation Velocity ◽  
Ultrasonic Wave Propagation ◽  
Carrier Liquid

The rheological response of magnetorheological fluid (MRF) results from the polarization induced in the suspended particles by application of an external magnetic field. Characteristics of an MRF depend on the volume faction, that is the percentage of magnetic particles in the carrier liquid. We propose a qualitative investigation of these volume fraction effects by measuring properties of ultrasonic wave propagation velocity in MRFs having various volume fractions. The ultrasonic wave propagation velocity changes under the effect of an external magnetic field as a result of arrangement of clusters along the direction of the field in the MRF.

Evolution of Acoustical, Geometrical, Physical, and Mechanical Parameters from Seedling to Cutting Age in Eucalyptus Clones Used in the Pulp and Paper Industries in Brazil

2019 ◽  
Vol 69 (1) ◽  
pp. 5-16 ◽  
Author(s):  
Raquel Gonçalves ◽  
Rafael Gustavo Mansini Lorensani ◽  
Monica Ruy ◽  
Nadia Schiavon Veiga ◽  
Gabriela Müller ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Ultrasonic Wave ◽  
Propagation Velocity ◽  
Paper Industry ◽  
Basic Density ◽  
Pulp And Paper ◽  
Wave Propagation Velocity ◽  
Production Chain ◽  
Ultrasonic Wave Propagation ◽  
Wood Processing

Abstract Wood-processing industries must be able to estimate the properties of wood to properly manage the wood production chain. For this estimation, changes in certain characteristics over time must be identified so that they can be used to rapidly differentiate a clone or species. Of interest are acoustical, geometrical, physical, and mechanical properties, all measurable in seedlings. Thus, the objective of this research was to analyze the evolution of the ultrasonic wave propagation velocity, diameter, height, basic density, strength, and stiffness starting in nursery seedlings at 3 months of age to trees at 6 years of age, which is the cutting age used by the pulp and paper industry in Brazil. The experiment was conducted in 121 seedlings and 270 trees of three Eucalyptus clones. Within the age range analyzed, the results indicated that all parameters have the potential to be used in a predictive model to estimate the future quality of clones, although the predictive value of these parameters varies. The ultrasonic wave propagation velocity was the only property that maintained the coherent differences among clones from the seedling to the cutting age (6 yr old). The strength, stiffness, diameter, and height maintained coherence from 12 months to the cutting age, whereas the basic density was maintained from the age of 24 months to the cutting age. We hope that these results will contribute to improving the methods to select clones.

scholarly journals Effect of Moisture Distribution on Velocity and Waveform of Ultrasonic-Wave Propagation in Mortar

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 790
Author(s):  
Shinichiro Okazaki ◽  
Hiroma Iwase ◽  
Hiroyuki Nakagawa ◽  
Hidenori Yoshida ◽  
Ryosuke Hinei
Keyword(s):  
Wave Propagation ◽  
Surface Layer ◽  
Moisture Content ◽  
Ultrasonic Wave ◽  
Propagation Velocity ◽  
Analytical Study ◽  
Quality Evaluation ◽  
Ultrasonic Method ◽  
Moisture Distribution ◽  
Ultrasonic Wave Propagation

Considering that the ultrasonic method is applied for the quality evaluation of concrete, this study experimentally and numerically investigates the effect of inhomogeneity caused by changes in the moisture content of concrete on ultrasonic wave propagation. The experimental results demonstrate that the propagation velocity and amplitude of the ultrasonic wave vary for different moisture content distributions in the specimens. In the analytical study, the characteristics obtained experimentally are reproduced by modeling a system in which the moisture content varies between the surface layer and interior of concrete.

scholarly journals Extensional Magnetorheology of Viscoelastic Human Blood Analogues Loaded with Magnetic Particles

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6930
Author(s):  
João M. Nunes ◽  
Francisco J. Galindo-Rosales ◽  
Laura Campo-Deaño
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Human Blood ◽  
Magnetic Particles ◽  
Volume Fraction ◽  
Flow Direction ◽  
Deborah Number ◽  
Simultaneous Application ◽  
String Structure ◽  
Breakup Time

This study represents a pioneering work on the extensional magnetorheological properties of human blood analogue fluids loaded with magnetic microparticles. Dynabeads M-270 particles were dispersed in Newtonian and viscoelastic blood analogue fluids at 5% wt. Capillary breakup experiments were performed, with and without the influence of an external magnetic field aligned with the flow direction. The presence of the particles increased the viscosity of the fluid, and that increment was larger when embedded within a polymeric matrix. The application of an external magnetic field led to an even larger increment of the viscosity of the working fluids, as the formation of small aggregates induced an increment in the effective volume fraction of particles. Regarding the liquid bridge stability, the Newtonian blood analogue fluid remained as a Newtonian liquid exhibiting a pinch-off at the breakup time in any circumstance. However, in the case of the viscoelastic blood analogue fluid, the presence of the particles and the simultaneous application of the magnetic field enhanced the formation of the beads-on-a-string structure, as the Ohnesorge number remained basically unaltered, whereas the time of the experiment increased due to its larger viscosity, which resulted in a decrease in the Deborah Number. This result was confirmed with fluids containing larger concentrations of xanthan gum.

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