Permanent Magnet Tubular Generator with Quasi-Halbach Array for Free-Piston Generator System

In this paper, the performance of a free-piston generator system with tubular single-phase stator winding is investigated for three different configurations of permanent magnet arrays on the mover: radial, rectangular quasi-Halbach and trapezoidal quasi-Halbach arrays. The optimal shape of the rectangular quasi-Halbach magnetization is obtained by employing an optimization technique called Imperialist Competitive Algorithm (ICA), and the results are compared with the previously developed permanent magnet linear generator (PMLG) with magnets of radial magnetization. Then, the resultant design of rectangular quasi-Halbach array, is changed to trapezoidal quasi-Halbach array and its performance is compared with other types of magnet arrays. The employed ICA is based on the analytical model of the magnetic flux distribution in air-gap, and is further verified by a nonlinear transient finite element (FE) model. The FE model has been developed to study the performance of the reciprocating PMLG. The accuracy of the proposed FE model is exemplified by comparing the calculated results with the experimental ones regarding the PMLG with radial magnetization

Finite Element Analysis of Galfenol Unimorph Vibration Energy Harvester

This paper develops a numerical model to examine the performance of the vibration energy harvester with one-rod (unimorph) of Iron-Gallium (Galfenol). The device\u27s principle of operation is based on inverse magnetostrictive effect of the Galfenol rod. In order to take into consideration the anisotropy of the Galfenol, the Armstrong model is employed that is implemented into a static 3-D finite element model (FEM) of the energy harvester. The predicted results from the numerical model are compared to the measured ones

Heat Generation Ability of Ferromagnetic Implants in Hyperthermia

In this paper, proposed implants in literature are compared in terms of the ability to heat generation in electromagnetic thermotherapy. To destroy the tumor cells, their temperature must rise above 42.5oC. The magnitude of the temperature rise depends strongly on the thermal conductivity of the tissue that has not been considered in most studies. For this reason, liver tissue is modeled using bioheat transfer equation that is coupled to the electromagnetic equations and electrical circuits by employing Multiphysics finite element package COMSOL, in order to create the numerical model of the system

Finite element analysis of magnetostrictive vibration energy harvester

PurposeThe paper aims to analyze the behavior of the Galfenol rods under bending conditions that are employed in a vibration energy harvester by illustrating the spatial variations in stress and magnetic field.Design/methodology/approachThis paper describes a 3‐D static finite element model of magnetostrictive materials, considering magnetic and elastic boundary value problems that are bidirectionally coupled through stress and field dependent variables. The finite element method is applied to a small vibration‐driven generator of magnetostrictive type employing Iron‐Gallium alloy (Galfenol).FindingsThe 3‐D static finite element modeling presented here highlights the spatial variations in magnetic field and relative permeability due to the corresponding stress distribution in the Galfenol rods subjected to transverse load. The numerical calculations show that about 1.1 T change in magnetic flux density is achieved which demonstrates the effectiveness of the inspected vibration‐driven generator in voltage generation and energy harvesting. The model predictions agree with the experimental results and are coherent with the magnetostriction phenomenon.Originality/valueThis paper fulfils the behavior analysis of Galfenol rods under transverse load that includes both compression and tension. The compressive and tensile stresses contributions to change in magnetic flux densities in the Galfenol rods were calculated by which the effectiveness of the inspected vibration‐driven generator in voltage generation and energy harvesting is demonstrated.</jats:sec