Experimental Investigation of Damping Effect in Semi-active Magnetorheological Fluid Sandwich Beam Under Non-Homogeneous Magnetic Field

Abstract

Despite the increased awareness of vibration control, vibration still causes many problems, such as performance degradation of the equipment and stability violation of flexible structures. In general, the vibration in machines can be caused due to the misalignment, malfunction of mounting parts, changes in temperature, and unbalanced rotating parts. Moreover, the fluctuation in magnetic force due alternating current in transformers and magnetically actuated device can cause unwanted vibrations. The development of sandwich-like structural system with combination of control capabilities plays a very important role to control the unwanted vibrations and to avoid resonance phenomenon due to external disturbances in the system. This problem can be resolved by applying a new sandwich structure incorporating smart fluids such as magnetorheological fluid. Here in this research work, design and fabrication of a sandwich beam consisting of three layers are undertaken; two outer layers of aluminium and one core layer of MR fluid. The fabricated sandwich beam is tested to effectively achieve vibration control under various magnetic field conditions. The research work results show that as the magnetic field intensity increases, the natural frequency of the beam increases, while the peak amplitude, loss factor, and quality factor are decreased. The principal criterion on the vibration control undertaken in this research work is the increment of the natural frequency as the field intensity increases. Therefore, the resonance behaviour of flexible structure, which can be occurred by external disturbances possessing several frequency spectrum, can be avoided by applying an appropriate magnetic field intensity. This directly means that the natural frequency of the smart sandwich beam can be adaptively controlled by using MR fluid which provides high damping and stiffening effect by means of the semi-active control which does not require any external input power.