The influence of the externaldc magnetic field on the amplitude dependence of ferromagnetic internal friction

1971 ◽  
Vol 22 (4) ◽  
pp. 747-750 ◽  
Author(s):  
Corneliu Anghel
Keyword(s):  
Magnetic Field ◽  
Internal Friction ◽  
Amplitude Dependence

Effect of a magnetic field on the elastic modulus and internal friction of alloy oKh27YU5A

1981 ◽  
Vol 13 (11) ◽  
pp. 1393-1396
Author(s):  
T. G. Kovaleva ◽  
A. D. Shevchuk ◽  
P. I. Tereshchenko
Keyword(s):  
Magnetic Field ◽  
Elastic Modulus ◽  
Internal Friction

Amplitude dependence of the internal friction of Cu-Mn-Al alloys with a martensite transformation

1991 ◽  
Vol 33 (3) ◽  
pp. 235-238 ◽  
Author(s):  
V. A. Evsyukov ◽  
V. M. Kopylova ◽  
N. V. Agapitova ◽  
M. N. Garshina ◽  
L. V. Nikiforova
Keyword(s):  
Internal Friction ◽  
Martensite Transformation ◽  
Al Alloys ◽  
Amplitude Dependence

A Mathematical Model for Internal Friction and Local Fatigue Damage Based on Populations of Yielding Microelements

1987 ◽  
Vol 109 (2) ◽  
pp. 201-206 ◽  
Author(s):  
P. W. Whaley
Keyword(s):  
Mathematical Model ◽  
Internal Friction ◽  
Fatigue Damage ◽  
Strain Energy ◽  
Crack Nucleation ◽  
Second Law Of Thermodynamics ◽  
Microplastic Deformation ◽  
Irreversible Processes ◽  
Amplitude Dependence ◽  
Microplastic Strain

A mathematical model for internal friction and fatigue damage based on populations of yielding microelements is described. Using two parameters, the model accounts for amplitude dependence of material damping. For low excitation levels the Zener theory of thermoelasticity is reproduced. The significance of this new damping model is that fatigue damage due to local accumulations of microplastic deformation is quantified. The entropy production is defined by expressing the second law of thermodynamics for irreversible processes as an equality, and quantifying local accumulations of microplastic strain energy as the source of irreversibility. A critical entropy threshold is defined in terms of the local microplastic strain energy density of local failure. The hypothesis is offered that local fatigue damage leading to crack nucleation occurs by exceeding the critical entropy threshold.

Internal Friction of Cast Graphite-Magnesium Composites

1988 ◽  
Vol 120 ◽  
Author(s):  
J. H. Armstrong ◽  
S. P. Rawal ◽  
M. S. Misra
Keyword(s):  
Internal Friction ◽  
Strain Amplitude ◽  
Friction Model ◽  
Piezoelectric Composite ◽  
Amplitude Dependence ◽  
Friction Behavior ◽  
Dislocation Densities ◽  
The Matrix ◽  
Composite Strain ◽  
Zr Alloy

AbstractInternal friction behavior in cast 8-ply [0°1 P55Gr/Mg-0.6%Zr alloy and P55Gr/Mg-1%Mn composites as a function of vibratory strain amplitude was measured at 80 kHz using a Marxtype piezoelectric composite oscillator. Both the matrix and composite exhibited strain amplitude independent internal friction below ε ≈ 10−6, while significant strain amplitude dependence was noted at higher strain levels. A maxima in damping was observed for most of the specimens tested. Heat treatment to enlarge grain size was found to increase both the strain amplitude independent and dependent internal friction of the composite. Strain amplitude dependence of the internal friction, including the existence of the maxima, was explained by the Granato-Lucke (G-L) dislocation internal friction model. Dislocation densities obtained from various TEM images from the fiber-matrix interface were compared to values predicted by G-L theory.

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