A novel high temperature eddy current damper with enhanced performance by means of impedance matching
When an electrically conductive material is exposed to time-varying magnetic fields, eddy currents are generated inside the conductor which oppose the change in the magnetic field. When eddy currents circulate through the conductor they are dissipated in form of heat due to the resistivity of the ma...
| Autores: | , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | Universidad de Alcalá (UAH) |
| Repositorio: | e_Buah Biblioteca Digital Universidad de Alcalá |
| Idioma: | inglés |
| OAI Identifier: | oai:ebuah.uah.es:10017/64200 |
| Acceso en línea: | http://hdl.handle.net/10017/64200 https://dx.doi.org/10.1088/1361-665X/aafc11 |
| Access Level: | acceso abierto |
| Palabra clave: | Vibration control Damping Eddy currents Magnetic fields High temperature Vibration Electrónica Electronics |
| Sumario: | When an electrically conductive material is exposed to time-varying magnetic fields, eddy currents are generated inside the conductor which oppose the change in the magnetic field. When eddy currents circulate through the conductor they are dissipated in form of heat due to the resistivity of the material. For low frequency vibrations, eddy current damping force is proportional to the vibration speed. Therefore, damping of vibrations at low frequencies or displacement amplitudes becomes increasingly difficult using this technology. Typical damping densities of eddy current dampers range between 0.1 for most devices and 2 MN s m(-4) for bestin-class prototypes. Those values are relatively low compared with, for examples, hydraulic dampers that can reach up to 4 MN s m(-4) . This low density limits potential applications of the technology. In addition, certain applications like vibration isolation of aircraft engines may require the damper to operate at high temperatures. However, most of current damping solutions are rarely effective at temperature higher than 100 degrees C because they frequently use NdFe magnets. In this paper, a passive eddy current damper with enhanced performance for use in high temperatures is presented. The Z-Damper takes advantage from impedance matching inside a magnetic linear gear to amplify the input vibration motion, maximizing the effectiveness of an integrated eddy current damper. SmCo magnets and high temperature components are used in the Z-Damper, potentially enabling operation in a wide temperature range. A theoretical model describing the dynamic behavior of the Z-Damper is presented and a set of experiments were conducted to evaluate its performance. A prototype of the Z-Damper has been designed, manufactured and experimentally demonstrated in a temperature range from 25 degrees C to 200 degrees C under low frequency (up to 60 Hz) harmonic excitations. A maximum equivalent viscous damping coefficient of 35 Ns mm(-1) , measured at 200 degrees C, has been achieved. A damping density of 8.4 MN s m(-4) is calculated. |
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