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Multiband damping of resonant vibrating piezoelastic structures by using digital adaptive passive shunting

This contribution is concerned with passive vibration damping via a digital shunting device. This device is capable to simulate arbitrary R-L input / output-phase behaviour and is able to adjust these parameters in real time to fulfil the underlying structural demands. The virtual resonator is coupled with a capacitive piezoelectric patch bonded on the vibrating structure. The software implementation of the R-L circuit offers the possibility of adaptive adjustment and frequency tracking in case of eigenfrequency shifts on the vibrating structure that can happen due to temperature and structural stress changes. The multi band damping is realized by increasing the number of virtual R-L shunts connected in parallel. In order to separate the individual resonators and decrease the mutual influence, an additional virtual capacitor for each R-L section is needed. The algorithms are evaluated on a simple mathematical example equipped with a piezoelectric element. To demonstrate the capabilities of the system tests were carried out on a steel plate and a mechanical harmonic oscillator. By placing the patch on a common anti-node of different frequencies the digital shunting device is able to damp selected eigenfrequencies. The effectiveness of the passive shunting device was demonstrated during tests, where a reduction of the vibration level up to 15 dB was achieved.