1,720,972 research outputs found
Non-linear modeling of a bi-layer magnetostrictive cantilever considering ΔE effect
No full textMagnetostrictive cantilever beams are reliable and straightforward energy harvesting devices for powering wireless sensors using environmental vibrations. However, despite their widespread use, a comprehensive analytical model encompassing both mechanical and electromagnetic main features is still lacking. The mechanical-to-magnetic coupling of a magnetostrictive beam, with its various working conditions and nonlinear characteristics, can be effectively approximated by the Euler–Bernoulli (E–B) equation with damping (viscous and Kelvin–Voigt) coupled with a non-linear magnetostrictive model. In this study, we propose a practical and convenient model for a general concept device designed to convert vibrations into electrical energy. The model is thoroughly compared with experimental measurements aimed to prove the goodness of the approach rather than energy harvesting highest performance. © 2024 The Author(s
Piecewise Linear Modeling for Inrush Safety Regions Detection and Its Validation Through a Preisach Model and Experimental Data
Full text linkAn alternative modeling approach to detect the occurrence of Inrush currents in power transformers, is discussed. The inrush current phenomenon is affected by the core residual magnetizazion Jr and voltage source initial phase , θ 0 , through which a region in the Jr – θ 0 plane where inrush currents doesn’t occur (named Inrush Safety Region - ISR) is defined. The approach is founded on the awareness that a fairly accurate description of the inrush process does not require a detailed description of core magnetization process, leading to the employment of a Piecewise linear magnetization model, able to detect in a straightforward way the ISR. The main advantage of the approach is to set up a fast algorithm for ISR detection, suitable for a real-time control. An accurate model of the transformer, based on a Preisach model magnetization algorithm has been exploited, along with a suitable set of experimental results allow to confirm the validity of the proposed identification approach
Magneto-mechanical optimization and analysis of a magnetostrictive cantilever beam for energy harvesting
No full textCORRENTI INDOTTE DALL’EFFETTO VILLARI IN DISPOSITIVI MAGNETOSTRITTIVI PER IL POWER HARVESTING
No full textExperimental Assessment of the Stress–Strain Behaviour of Leighton Buzzard Sand for the Calibration of a Constitutive Model
No full textA number of constitutive models are nowadays implemented in numerical codes which simulate the stress–strain behaviour of soil from very small to large strain. In this paper, the mechanical behaviour of Leighton Buzzard sand (grade E), used worldwide for physical modelling, has been thoroughly characterized by laboratory testing along several stress paths. Tests were aimed at calibrating a constitutive model, that allows considering stiffness nonlinearities in a wide range of strains, in the framework of isotropically hardening plasticity. As a validation, the results of dynamic centrifuge tests on a layer of the same sand were compared with finite element predictions
Eddy Current losses in ferromagnetic laminations
No full textAbstract. It is demonstrated through the comparison of analytical, numerical, and experimental results that the existence of excess eddy current losses can be explained by the peculiar nature of the nonlinear diffusion of electromagnetic fields in magnetically nonlinear laminations. The essence of this peculiar nature is that nonlinear diffusion occurs as inward progress of almost rectangular profiles of magnetic flux density of variable height. Approximating actual profiles of magnetic flux density by rectangular ones, the problem of nonlinear diffusion can be treated analytically by using a simple model. The accuracy and the limit of applicability of the rectangular profile model are discussed by comparing its predictions with finite elements numerical solutions of nonlinear diffusion equation as well as with experimental results. © 2000 American Institute of Physics. [S0021-8979(00)24808-1
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