In order to reduce structural vibrations in narrow frequency bands, tuned mass absorbers can be an appropriate measure. A quite similar approach which makes use of applied piezoelectric elements, instead of additional oscillating masses, are the well-known resonant shunts, consisting of resistances, inductances, and possibly negative capacitances connected to the piezoelectric element. This paper presents a combined approach, which is based on a conventional tuned mass absorber, but whose characteristics can be strongly influenced by applying shunted piezoceramics. Simulations and experimental analyses are shown to be very effective in predicting the behavior of such electromechanical systems. The vibration level of the absorber can be strongly attenuated by applying different combinations of resistant, resonant, and negative capacitance shunt circuits. The damping characteristics of the absorber can be changed by applying a purely resistive or resonant resistant shunt. Additionally, the tuning frequency of the absorber can be adapted to the excitation frequency, using a negative capacitance shunt circuit, which requires only the energy to supply the electric components.

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In this paper, a new tuning method for shunt damping with a series resistance, inductance and negative capacitance is proposed and its validity is investigated. It is based on the measured electromechanical impedance of a piezoelectric system, which is represented through an equivalent electrical circuit that takes into account the characteristics of the piezoelectric transducer and the host structure. Afterwards, an additional circuit representing the shunt is connected and the Norton equivalent impedance is obtained at the terminals that represent the mechanical mode of interest. During the tuning process, the optimal shunt parameters are found by minimizing the maximum absolute value of the Norton equivalent impedance over a defined frequency range through a numerical optimization. Taking benefit from the analogy between electrical impedance and mechanical admittance, the minimization of different mechanical responses (displacement, velocity or acceleration) is also proposed and the different optimum shunt parameters obtained are compared. In view of real technical applications, this method allows the integration of a real negative capacitance circuit, i.e., a negative impedance converter, rather than an ideal component. It is thus possible to use the impedance of this circuit and optimize the individual component values. Since this method is based on one simple measurement, it can be applied to arbitrary structures without the need of complex dynamic tests or expensive finite elements calculations. Finally, an experimental analysis is carried out in order to compare the damping performance of the proposed method and the conventional analytical method that minimizes a mechanical frequency response function