Eventos Anais de eventos
ENCIT 2016
16th Brazilian Congress of Thermal Sciences and Engineering
TRANSIENT THERMAL ANALYSIS OF A MAGNETORHEOLOGICAL CLUTCH
Submission Author:
Arnaldo Leal Junior , ES
Co-Authors:
Rafhael M Andrade, Antonio Bento Filho
Presenter: Arnaldo Leal Junior
doi://10.26678/ABCM.ENCIT2016.CIT2016-0130
Abstract
Magnetorheological (MR) fluids are smart materials which can have their properties controlled by an induced magnetic field. The application of MR fluids in clutches devices is increasing due the ability to control the coupling torque and velocity between two shafts, and the possibility to have a progressive coupling between axes. Despite the great properties and benefits, the MR fluid properties are strongly related to the temperature. When the fluid temperature reaches certain limit, the fluid additives begin to deteriorate and the viscosity of the carrier fluid starts to change, which can lead to irreversible changes on the MR fluid and uncontrollability of its rheological properties. This paper presents a thermal analysis of a MR clutch to address some limitations of the MR fluid with respect of working conditions. Two analyses are developed, the first one is a thermal analysis of the clutch in the full slip condition. This condition occurs when the torque required to moving a load is greater than the clutch maximum torque. Since the heat generation is high, full slip condition is the most dangerous condition for the clutch. The model proposed evaluates the time limit of the clutch on this condition before the MR fluid starts to deteriorate. The second analysis is for the clutch working for 8 hours straight. The objective of the second analysis is to determine the temperature of the MR fluid region after a long term operation. A correlation equation between the fluid shear stress and temperature is applied to evaluate the clutch output torque variation. Results show that the full slip operation must be avoided due to the higher temperatures on the fluid region. Although the long term operation analysis shows the fluid region in temperatures below the maximum MR fluid temperature, it still can significantly decrease the output torque.
Keywords
Magnetorheological clutch, transient thermal analysis, magnetorheological fluid.
