Electromagnetic shunt damping with negative impedances: Optimization and analysis

Dynamic vibration absorbers (DVA) are classic and effective devices to reduce the amplitude of vibration sustained by structures. A promising alternative to the DVAs is the electromagnetic shunt damper (EMSD), in which the electrical shunt circuit serves as the absorbing oscillator. The objective of this paper is to carry out optimum designs of an EMSD connected to a resistive-inductive-capacitive (RLC) shunt circuit, by adopting three different calibration strategies: the fixed points theory, H-2 optimization criterion and maximum damping criterion. The aforementioned optimization strategies are appropriate to different excitation scenarios: harmonic, random and transient vibration, respectively. Analytical expressions of optimal parameters are formulated in terms of the ratio of external inductance in the shunt and inherent inductance of electromagnetic transducer. Lower bounds of inductance ratio in the region of stability are also specified for each strategy, based on which the ultimate attainable performance of EMSDs can be predicted. Numerical investigation underlines that including a negative inductance in the shunt always contributes to reduce the frequency response magnitude, broaden the absorbing area around targeted vibration mode, increase the damping performance, and thereby accelerate the decay rate of transient vibration. (C) 2019 Elsevier Ltd. All rights reserved.