•Shunted piezoelectric vibration absorber for broadband vibration control.•Maximisation of the time-averaged electric power absorbed by the shunt.•Two-paths tuning sequence for the optimisation of ...the shunt resistance and inductance.•Online tuning using an extremum seeking gradient search algorithm.
This paper is focussed on the extremum seeking online tuning of a shunted piezoelectric vibration absorber for the broadband control of the resonant response of a mechanical system subject to a stationary stochastic excitation. Two shunt circuits are considered, which are formed by a resistor and an inductor connected either in series or in parallel. The two components are tuned in such a way as to maximise the time-averaged electric power absorbed by the shunt, that is the time-averaged electric power dissipated by the shunt resistor. The paper shows that the proposed tuning approach leads to the same optimal resistive-inductive components of the shunt that would minimise the time-averaged vibration response of the mechanical system. Also, it demonstrates that the electric power objective function is characterised by a bell-type non-convex surface with a single maximum. Furthermore, it shows that the cost function has two principal directions characterised by constant-resistance and constant-inductance respectively. Accordingly, a two-paths tuning sequence is proposed, where the shunt inductance and resistance are tuned sequentially with an extremum seeking gradient search algorithm, which efficiently finds the optimal values by working along the two principal directions.
All structures experience vibrations due to external dynamic force excitations, such as earthquakes and wind loadings. At resonance, the impact of this natural dynamic force on structures may lead to ...structural failures. Hence, an absorber is mounted to absorb vibrations from the primary system. Unfortunately, passive tuned mass absorbers can only target a single frequency. Since structural buildings possess multiple modes, an adaptive or tune-able vibration absorber is needed to attenuate the vibration in a multi-degree of freedom (MDOF) system. In this work, an adaptive electromagnetic vibration absorber (AEMVA) is proposed to eliminate the effects of vibrations and is dynamically tuned using electromagnets. By varying the current supplied to the coil, the stiffness of the AEMVA can be adjusted, resulting in a varying absorber frequency. A mathematical description of the AEMVA on a three-story prototype model building is also presented. The three-story benchmark model was used to demonstrate the effectiveness of AEMVA in absorbing multiple vibration modes, both analytically and experimentally. It is shown that 68.81 %, 50.49 %, and 33.45 % of vibration amplitude reductions were achieved at the first, second, and third modes, respectively.
Performance of MRE-based Vibration Absorbers Lerner, A. Albanese; Cunefare, K.A.
Journal of intelligent material systems and structures,
05/2008, Letnik:
19, Številka:
5
Journal Article
Recenzirano
The purpose of this work is to use magnetorheological elastomers (MREs) as field-dependent springs within three vibration absorber configurations, and to determine their vibration absorption ...characteristics. Magnetorheological elastomers are fabricated from silicone gel and iron microparticles, and implemented as tunable springs in three vibration absorber configurations, which excited the MREs in shear, squeeze mode, and compression. Each vibration absorber configuration exploits different magneto-mechanical properties, achieving very different results. The MRE iron concentration is varied to find the largest natural frequency shift for the squeeze-mode absorber due to an applied magnetic field. Absorbers with MREs containing 35% iron by volume exhibits the largest natural frequency shift, 507%. MREs containing 35% iron are placed into shear and longitudinal mode vibration absorber devices, which exhibit 470% and 180% frequency increases, respectively.
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