On the evening of Dec. 23, 2015, Prof. Ramin who comes from University of Concordia gave our students a lecture about Semi-Active Control of Torsional Vibrations using a MR based-Hybrid Rotary Damper.
Machinery systems with rotating components such as crankshafts in automobile and turbine rotor shaft in aircraft engines experience torsional vibrations. Excessive torsional vibrations if not controlled properly may cause severe system performance limitation, excesses noise and stress and even early fatigue failure. Centrifugal Pendulum Vibration Absorber (CPVA) is an effective passive torsional vibration absorber (TVA) that has been widely used in rotating and reciprocating machines to suppress torsional vibrations. While CPVAs are simple and reliable torsional vibration absorbers that are expected to be efficient under steady-state conditions, they have shown performance limitations for unsteady and unpredictable environmental conditions. MR based-torsional vibration absorbers are promising energy absorption devices for semi-active control of torsional vibrations due to their inherent fail-safe feature, low power requirement and their adaptability to varying external exactions.
In this research seminar, first the governing equations of conventional CPVA and rotary MR damper will be derived. An optimum design strategy has been formulated to maximize the dynamic range of a rotary MR damper under volume and inertial constraints. The rotary MR damper with optimal design geometry has been fabricated and then tested to evaluate its damping performance under varying applied magnetic field. A new hybrid rotary MR damper combing CPVA and rotary MR damper has been proposed in which CPVA has been connected to the housing of the rotary MR damper. A closed-loop feedback control system using semi-active skyhook control algorithm has been used to control the damping torque in the proposed hybrid rotary MR damper. Finally, the performance of CPVA, rotary MR damper and hybrid rotary MR damper to attenuate vibration has been studied and compared.
