Experimental Evaluation of Transient Magnetic Fields for Magnetorheological Sandwich Beam Damping

The purpose of this study is to create and calibrate a numerical model that accurately describes the dynamics of a magnetorheological (MR) sandwich beam influenced by an electromagnet. This task is achieved by first deriving the equation of motion for the beam, with a particular focus on incorporating a complex shear modulus that describes the core layer stiffness. A modal analysis provides an approximation of the shear modulus at various magnetic field strengths, while a free-decay analysis measures the time it takes for the beam’s vibrations to decay to a suitable amplitude. This paper also focus on the design of the electromagnet that will influence the beam. The experimental free-decay results indicate that the decay time is faster with the magnet on than with it off, regardless of the magnetic field's strength. However, the model instead predicts that increasing the field strength will slow the decay. This difference may arise from unwanted magnetic hysteresis and a difference in damping models between the time- and frequency-domain analyses. Future research will focus on remedying these differences by changing parameters of the beam such as its material and magnetization properties.