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1.
Design and optimization of a spherical magnetorheological actuator
Jakob Vizjak, Anton Hamler, Marko Jesenik, 2023, original scientific article

Abstract: Recently, an increasing number of electromagnetic devices have been using smart fluids. These include ferrofluids, electrorheological fluids, and magnetorheological (MR) fluids. In the paper, magnetorheological fluids are considered for use in a spherical actuator for haptic applications. An approach is presented to the design and optimization of such a device, using finite element method modelling linked with differential evolution (DE). Much consideration was given to the construction of the objective function to be minimized. A novel approach to objective function assembly was used, using reference values based on the model design and created with parameters set to the midpoint values of the selected range. It was found to be a useful strategy when the reference values are unknown. There were four parameters to be optimized. Three of them gravitated towards the boundary value, and the fourth (actuator radius) was somewhere in between. The value of the objective function reached a minimum in the range of actuator radius between 42.9880 mm and 45.0831 mm, which is about a 5% difference in regard to the actuator radius. Three passes of optimization were performed with similar results, proving the robustness of the algorithm.
Keywords: magnetorheological fluid, finite element method, FEM, optimization, differntial evolution, DE, actuator
Published in DKUM: 22.05.2024; Views: 173; Downloads: 11
.pdf Full text (4,69 MB)
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2.
Analiza vpliva magnetnega polja na viskoznost in grelno moč magnetne tekočine : magistrsko delo
Jakob Vizjak, 2019, master's thesis

Abstract: Magnetne tekočine sodijo v kategorijo nanomaterialov zaradi velikostnega razreda suspendiranih magnetnih nanodelcev v nosilni tekočini. Njihova uporabnost se kaže na različnih področjih inženiringa, znanosti in medicine. Ena izmed pomembnejših lastnosti magnetne tekočine je viskoznost, ki je bila predmet opazovanja v magistrski nalogi. Vpliv viskoznosti smo preverili teoretično kot tudi eksperimentalno. V teoretičnem delu smo uporabili in prilagodili matematični model izračuna izgub magnetne tekočine v visokofrekvenčnem magnetnem polju ter raziskali vpliv različnih modelov viskoznosti suspenzije in različnih nosilnih tekočin. Za validacijo matematičnega modela izgub smo na izbranem vzorcu opravili serijo meritev izgub po kalorimetrični metodi, pri kateri se glede na temperaturni odziv merjenca ugotovi specifična stopnja absorpcije (SAR). V eksperimentalnem delu naloge smo opravili meritve viskoznosti možnih nosilnih tekočin po dveh različnih metodah, in sicer najprej s Hoepplerjevim in nato z rotacijskim viskozimetrom. V sklopu meritev z rotacijskim viskozimetrom smo sistematično skušali ugotoviti temperaturno odvisnost in dokazati pojav magnetoreologije.
Keywords: magnetne tekočine, specifična absorpcijska stopnja, viskoznost, magnetne izgube, magnetno polje
Published in DKUM: 22.11.2019; Views: 1470; Downloads: 142
.pdf Full text (4,32 MB)

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