Open Access
Polycaprolactone/MSMA composites for magnetic refrigeration applications
(Wiley, 2024-09-06) Sánchez-Alarcos Gómez, Vicente; Khanna, Deepali; La Roca, Paulo Matías; Recarte Callado, Vicente; Lambri, Fernando Daniel; Bonifacich, Federico Guillermo; Lambri, Osvaldo Agustín; Royo Silvestre, Isaac; Urbina Yeregui, Antonio; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
A high filling load (62% weight) printable magnetic composite has been elaborated from the dispersion of magnetocaloric Ni45Mn36.7In13.3Co5 metamagnetic shape memory alloy microparticles into a PCL polymer matrix. The composite material has been prepared by solution method, resulting in a very homogeneous particles dispersion into the matrix. The structural transitions in the polymer are not affected by the addition of the metallic microparticles, which in turn results in a significant increase of the mechanical consistency. The good ductility of the elaborated composite allows its extrusion in flexible printable filaments, from which 3D pieces with complex geometries have been grown. The heat transfer of the composite material has been assessed from finite element simulation. In spite of the achievable magnetocaloric values are moderated with respect to the bulk, numerical simulations confirm that, in terms of heat transference, a PCL/Ni-Mn-In-Co wire is more efficient than a bulk Ni-Mn-In-Co cubic piece containing the same amount of magnetic active material. The quite good magnetocaloric response of the composite and the possibility to print high surface/volume ratio geometries make this material a promising candidate for the development of heat exchangers for clean and efficient magnetic refrigeration applications.
Open Access
Thrust actuator with passive restoration force for wide gap magnetic bearings
(Elsevier, 2019) Royo Silvestre, Isaac; Beato López, Juan Jesús; Castellano Aldave, Jesús Carlos; Gómez Polo, Cristina; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
Active thrust magnetic bearings provide an axial force to balance the moving parts of machines. However, most devices produce null or unbalancing passive forces. Furthermore, reported designs usually feature very small axial and radial gaps. This paper presents a thrust actuator for wide axial gaps that produces both passive and active restoring axial forces. It features a long biconical rotor and a stator housing a single winding and two permanent magnets. Simulations are done using finite-element-analysis (FEA) and compared to magnetic circuit analysis and experimental results from a prototype with a diameter of 48 mm and 20 mm axial displacement.
Open Access
Electromagnetic vibrational harvester based on U-shaped ferromagnetic cantilever: a novel two-magnet configuration
(Elsevier, 2024-09-07) Gandía Aguado, David; Garayo Urabayen, Eneko; Beato López, Juan Jesús; Royo Silvestre, Isaac; Cruz Blas, Carlos Aristóteles de la; Tainta Ausejo, Santiago; Gómez Polo, Cristina; Ciencias; Zientziak; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC
Electromagnetic vibrational harvesters are low-cost devices featuring high-power densities and robust structures, often used for capturing the energy of environmental vibrations (civil infrastructures, transportation, human motion, etc.,). Based on Faraday's law, energy generation relies on the modification of the magnetic field distribution within a magnetic element caused by mechanical vibrations inducing an electromotive force (EMF) in a pick-up coil. However, the practical implementation of this type of vibrational harvester is currently limited due to the reduced generated power under low-frequency vibrations. In this work, an electromagnetic vibrational harvester is experimentally characterized and analyzed employing magnetic circuit analysis. The harvester consists of a ferromagnetic U-shaped cantilever, a NdFeB magnet and a ferrite magnet used as ¿magnetic tip mass¿ to enhance the magnetic flux changes under vibrations of frequency < 100 Hz. For this configuration, an experimental voltage of ¿ 1.2 V peak-to-peak (open circuit) was obtained at a resonant frequency of 77 Hz, enabling the subsequent electronic rectification stage. Additionally, Finite Element Method (FEM) is used to explore different design possibilities including the modeling of complex geometries, mechanical properties and non-linear magnetic materials, enabling the tuning of the resonance frequency from 51 to 77 Hz, keeping constant the induced voltage.
Open Access
Fast calculation methods for the magnetic field of particle lattices
(AIP Publishing, 2025-02-14) Royo Silvestre, Isaac; Gandía Aguado, David; Beato López, Juan Jesús; Garayo Urabayen, Eneko; Gómez Polo, Cristina; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
With the rise of 3D printing and composite materials, components comprising dispersed magnetic particles have become more interesting due to the possibility to design magnetic elements of any shape with varying amounts of the actual magnetic material. However, quick and easy calculation methods are needed to design these components enabling the selection of the optimum required percentage of magnetic particles (millimeter parts contain billions of micro-sized particles). This work proposes a semi-analytical iterative method for the estimation of the magnetic field generated by magnetic composites formed by embedded magnetic particles. The model is compared in terms of accuracy and calculation speed with finite element analysis and the average magnetization model of the magnetic composite. The results are finally supported by the comparison with experimental measurements of the weak magnetic field generated by a magnetic particle lattice.
Open Access
A combination of a vibrational electromagnetic energy harvester and a giant magnetoimpedance (GMI) sensor
(MDPI, 2020) Beato López, Juan Jesús; Royo Silvestre, Isaac; Algueta-Miguel, Jose M.; Gómez Polo, Cristina; Zientziak; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC; Ciencias; Ingeniería Eléctrica, Electrónica y de Comunicación; Gobierno de Navarra / Nafarroako Gobernua
An energy harvesting device combined with a giant magnetoimpedance (GMI) sensor is presented to analyze low frequency vibrating systems. An electromagnetic harvester based on magnetic levitation is proposed for the electric power generation. The device is composed of two fixed permanent magnets at both ends of a cylindrical frame, a levitating magnet acting as inertial mass and a pick-up coil to collect the induced electromotive force. At the resonance frequency (10 Hz) a maximum electrical power of 1.4 mW at 0.5 g is generated. Moreover, an amorphous wire was employed as sensor nucleus for the design of a linear accelerometer prototype. The sensor is based on the GMI effect where the impedance changes occur as a consequence of the variations of the effective magnetic field due to an oscillating magnetic element. As a result of the magnet’s periodic motion, an amplitude modulated signal (AM) was obtained, its amplitude being proportional to mechanical vibration amplitude (or acceleration). The sensor’s response was examined for a simple ferrite magnet under vibration and compared with that obtained for the vibrational energy harvester. As a result of the small amplitudes of vibration, a linear sensor response was obtained that could be employed in the design of low cost and simple accelerometers.
Open Access
Optimization procedure of low frequency vibration energy harvester based on magnetic levitation
(Elsevier, 2024) Royo Silvestre, Isaac; Beato López, Juan Jesús; Gómez Polo, Cristina; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Permanent magnets are widely employed in levitation-based vibration harvesters and sensors, but their operational range does not span ultra-low frequencies unless a mechanical resonator is added. In this work, an algorithm based on analytical equations has been implemented to design magnetic springs in resonant vibration energy harvesters operating at very low frequencies and the results have been comparatively checked and refined using 3D FEA (Finite Element Analysis). Particularly, a prototype based on a fixed ferrite and a mobile rare-earth magnet is designed, where the semi-analytical optimum solution was properly modified via FEA. The experimental induced pick-up voltage is characterized for ultralow vibrations (resonant frequency 1.7 Hz).
Open Access
U-shape magnetostrictive harvester: design and experimental validation
(IEEE, 2024-07-05) Gandía Aguado, David; Garayo Urabayen, Eneko; Beato López, Juan Jesús; Royo Silvestre, Isaac; Gómez Polo, Cristina; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Electromagnetic vibrational harvesters stand out due to their high-power density, long-life robust structure and low-cost design. Moreover, they can be designed using magnetostrictive materials. The mechanical vibrations cause stress on the magnetostrictive material, leading to variations in its magnetization. This, in turn, induces an electromotive force (EMF) in a well-designed pick-up coil system, thereby transforming mechanical energy into electrical energy. In spite of the potentiality of these electromagnetic harvesters, their practical implementation is limited due to the difficulties in the design optimization in terms of the device dimensions, effective stresses on the magnetostrive material, distribution and magnetic field strength of the permanent magnets and pick-up coil characteristics. Finite Element Methods (FEM) enable the estimation of the induced voltage and thus the output power as a function of harvester design parameters, allowing us to experiment with different configurations and identify optimal parameters.
Open Access
Micrometric non-contact position magnetoimpedance sensor
(Elsevier, 2018) Beato López, Juan Jesús; Royo Silvestre, Isaac; Gómez Polo, Cristina; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua, VITICS, IIM14244.RI1
In this work a sensitive micrometric non-contact position sensor based on the Giant MagnetoImpedance effect (GMI) is analyzed. A nearly zero magnetostrictive CoFeSiBCr wire was employed as sensor nucleus. The sensing principle is based on the changes in the high frequency electric impedance, Z, of the soft magnetic element as a function of the relative position of a permanent magnet generating a non-uniform magnetic field along the wires axis. The sensor sensitivity is analyzed in terms of the magnetic field gradient and wire's length. The comparison between the sensing response of a single wire element and a long wire (12 cm in length) with different voltage contacts along its axis is performed. Higher micrometric sensitivities are achieved in wires with a certain critical length. A slight enhancement of the sensor sensitivity is found under the single wire configuration below the critical wire length. These results are interpreted as the contribution of the characteristic closure domain structure at the sample ends in these soft magnetic wires. Finally, the application of the sensor for the detection of the daily micrometric trunk shrinkage variations in a lemon tree is presented. The results indicate that this type of magnetic sensors can be easily implemented in the agricultural sector, providing a low cost and sensitive detection technique regarding water monitoring purposes.