Magnetic response to cyclic fatigue of low carbon Fe-based samples

Abstract

The Preisach model formalism has been applied to analyse hysteresis measurement results for evaluating fatigue damage in Fe-C alloys caused by cyclic fatigue loading. Hysteresis loops and differential permeability curves were measured at various stages of the fatigue life of the samples. The parameters which were built by means of the PMF and the classical hysteresis magnetic parameters (such as saturation magnetization, coercive field and others) were studied as a function of the fatigue lifetime. The present results show that the Preisach model analysis can be used to improve the sensitivity of magnetic hysteresis measurements for non-destructive evaluation of the accumulation of fatigue damage in steel components.

Strong three-meson couplings ofJ/ψandηc

“…Within the dispersion formulation of the constituent quark model, the decay constants f P and f V of pseudoscalar and vector mesons are expressed in the form of relativistic spectral representations, over the invariant masses of the intermediate quark-antiquark states, of the spectral densities involving the nonperturbative meson wave functions φ P (s) and φ V (s), respectively [8]:…”

“…The explicit expressions for ∆ i (s 1 , s 2 , q 2 ) are given in Sect. 3.2 of [8] and will not be reproduced here. We point out that at q 2 < 0, the form factors obtained within the dispersion formulation are equal to the form factors of the light-front relativistic constituent quark model (Ref.…”

“…In the past, however, the application of QCD sum rules to three-meson couplings faced a great problem: QCD sum rules strongly underestimated the D * Dπ coupling (see, e.g., [7]) and the origin of this discrepancy has not been fully clarified. We thus present an alternative analysis of the family of J/ψ and η c couplings using the relativistic dispersion approach [8], one of the approaches which managed to predict correctly the D * Dπ coupling [9,10] before the CLEO measurement.…”

Nondestructive Evaluation of Early Contact Fatigue Using Eddy Current Pulsed Thermography

“…, and can be written for the derivatives in the following equation (6). (6) As the fatigue damage occurs at the area that suffers contact fatigue, the thermal and electrical conductivities of samples are varied [37][38][39]. Thus, both the spatial and transient of heat distribution is non-uniform at these areas.…”

“…During the fatigue process, the microstructure of the gear is changed. These changes lead to a considerable decrease in thermal conductivity, electrical conductivity and magnetic permeability [37][38][39]. The relationship between the heat distribution and these parameters can be established by using the pulsed eddy current thermography method.…”