Fabrication, Characterization and Control of a Novel Magnetorheological Elastomer-based Adaptive Tuned Vibration Absorber

Semi-active tunable vibration absorbers (SATVAs) have recently received growing interest due to their energy efficiency, simple structure and optimal performance under a wide frequency-bandwidth. SATVAs generally consist of elements with variable stiffness to allow for optimal performance under a wide frequency range compared with their passive analogues which are typically tuned at a particular frequency. Magnetorheological elastomers (MREs) are unique smart materials which can serve as the variable-stiffness elements in SATVAs. MREs are basically the solid state of the well-known magnetorheological (MR) fluids, which in contrast to MR fluids, their stiffness (storage modulus) can be continuously changed rapidly through the application of an external magnetic field. The present research study is concerned with the modeling, fabrication and control of a novel SATVA based on MRE-filled sandwich structures. To this end, a novel five-layered beam-shape sandwich structure was designed using MREs as core layers, reinforced with thin elastic plates on top, middle and bottom. To provide for a suitable and controllable magnetic field a set of U-shaped electromagnets were also designed. A specific two-node adaptive sandwich beam element has been developed to derive the governing dynamic equations of the MRE-based sandwich beam in the finite element (FE) form. The developed finite element model of the MRE-based sandwich beam together with the developed magnetic finite element of the electromagnets have then been effectively utilized to identify the suitable design parameters for the proposed SATVA to meet the geometrical and mechanical requirements. Experimental tests have been designed to acquire the magnetic permeability and the storage modulus of the fabricated MREs required for the modeling. Next the proposed SATVA was fabricated and subsequently tested using an electrodynamic shaker to evaluate its vibration performance and also to validate the developed FE models. The results indicate that the fabricated SATVA, provides an approximately 9% shift in the natural frequency. The validated FE models were subsequently utilized to conduct systematic sensitivity analysis to investigate the effect of different design parameters including the thickness of elastic layers and the position of electromagnets. The experimental results were also used to developed an equivalent lumped mass model for the proposed SATVA. Finally, a phased-based control strategy using the full-state adaptive Kalman filter (AKF) observer has been developed to adaptively tune the natural frequency of the absorber to the varying excitation conditions. It is expected that the present research dissertation provides an essential guidance for the future development of light-weight adaptive vibration absorbers