A mechanical
resonator has an electronically adjustable
resonance frequency and is especially adapted to be used as a tunable vibration absorber. The mechanical
resonator includes an
inertial mass mounted on a free end of a spring, which is secured at its other end to the structure that is to be vibrationally damped. In order to vary the resonant frequency of the
resonator, an electromechanical converter such as a piezoelectric element is connected to the spring and / or the
inertial mass, and a displacement and / or acceleration sensor provides a sensor
signal that is dependent on the respective displacement and / or acceleration of the spring and / or the
inertial mass. An electronic
control circuit generates an actuating
signal based on the sensor
signal. The actuating signal is applied to the electro-mechanical converter, which responsively exerts an adjusting force onto the spring and / or the inertial
mass. The
control circuit may include one or more variable amplifiers, inverters, and phase shifters, to control the actuating signal such that the adjusting force exerted by the electromechanical converter either counteracts or reinforces the
bending force exerted by the inertial
mass on the spring. In this manner, the effective total spring constant of the resonator can be increased or decreased relative to the inherent spring constant of the spring, whereby the resonant frequency is adjusted.