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Numerical optimization and realization of distributed and adaptive neutralizers

: Pöllmann, J.; Herold, S.; Mayer, D.; Röglin, T.; Rue, G.J. de; Schmidt, Matthias; Vrbata, J.

Carrera, E. ; Fraunhofer-Institut für Zerstörungsfreie Prüfverfahren -IZFP-, Institutsteil Dresden; European Community on Computational Methods in Applied Science -ECCOMAS-:
6th ECCOMAS Thematic Conference on Smart Structures and Materials, SMART 2013 : Politecnico di Torino, 24-26 June 2013
Torino, 2013
14 S.
Thematic Conference on Smart Structures and Materials (SMART) <6, 2013, Torino>
Fraunhofer LBF ()
numeric; optimization; distributed neutralizer; vibration neutralizer; vibration absorber

In many technical structures like engines unwanted vibrations can have an influence on performance and lifetime. Furthermore these vibrations may lead to undesirable behavior as well as noise. The disadvantages can be overcome during the ramp up, using neutralizers [1]. This work considers a 3D truss structure as an abstraction of complex structures. For this structure two different typical positioning schemes are treated. On one hand the absorbance of one neutralizer at the force excitation is considered. On the other hand four distributed neutralizers at the mounting points are optimized.
For both considerations a numerical optimization, e.g. SQP is used to adjust the parameters of one and four neutralizers, respectively. Moreover, the different impact of passive and adaptive neutralizers is considered as well. The simulations indicate that four distributed adaptive neutralizers maintain the same effectiveness as passive neutralizers, using a fraction of the required mass [2]. The optimization results are validated with measurements on real devices. For this purpose different neutralizers are built. The passive neutralizers consist of clamped steel beams with attached masses. For the adaptive neutralizers two different designs are chosen. The first design is an extension to the passive neutralizer concept with piezoelectric patch transducers bonded at the beam. With the help of a feedback control the eigenfrequency can be shifted. At the second design the adaptive neutralizers are actuated using electric motor that push apart two parallel leaf springs. This pre-stresses the springs and changes the geometry, thus changing the resonance.