Dynamic analysis of palm oil-based magnetorheological fluid in mitigating the Sommerfeld effect of a rotor dynamic system

This study explores the development and characterization of palm oil-based magnetorheological fluid (MRF) behaviour and its dependency on dynamic conditions through a semi-analytical approach. Magnetorheological fluid viscosity can be rapidly adjusted by applying a magnetic field to control and modulate the damping force in various mechanical systems. The effectiveness of the prepared magnetorheological fluid was analysed through experimental rheological characterization, and the obtained properties were incorporated into a semi-analytical rotor dynamic model to evaluate vibration attenuation. The rheological behaviour of the magnetorheological fluid was tested under varying currents supplied to the magnetorheological damper from 0 to 1 A. Magnetorheological fluid exhibited shear-thinning behaviour with increasing shear rate and current. The storage modulus and the loss modulus both increased with frequency and current increment, which enhances the material's viscoelastic properties at higher current. Yield stress tests showed a significant rise in yield force with increasing current, from 65 N at 0 A to 586 N at 0.9 A, due to the alignment of magnetic particles enhancing resistance to fluid movement. The vibration amplitude of the rotor system was attenuated from 12.82 to 2 mm with the increase of the current supply to the magnetorheological damper. This study is helpful to those applications where adjustable viscosity and stress are controlled through a magnetic field for vibration attenuation of the rotor dynamic system.