ISBN 9783843951708

978-3-8439-5170-8, Reihe Luftfahrt

Timo Theurich
Predictive design and experimental validation of the working principle of impact energy scatterers used for vibration mitigation of externally forced or self-excited structures

138 Seiten, Dissertation Universität Stuttgart (2022), Softcover, A5

Zusammenfassung / Abstract

In this work, a special type of nonlinear vibration absorber is considered; a small mass undergoing impacts within a cavity of a host structure.

The highly nonlinear coupling via impacts enables the absorber to engage into resonance captures with the host structure at arbitrary frequencies.

Additionally to their ability to locally dissipate energy due to inelastic material behavior in the contact region, impacting vibration absorbers are able to scatter energy to high-frequency vibration modes, where it is dissipated effectively on a fast time scale.

The aim of this thesis is to gain deep insight into the working principle of such impacting absorbers.

The theoretical and experimental analysis of the working principle reveals that such absorbers owe their high efficacy primarily to the modal energy scattering effect, when used within flexible host structures.

In this sense, such devices are termed impact energy scatterers.

A semi-analytical design approach is introduced, capable of considering the scattering effect. The approach is designed for the regime of resonance with an externally forced mode or negatively damped mode.

It is concluded that the proposed semi-analytical procedure enables deep qualitative understanding of the problem and, at the same time, yields a quantitatively accurate prediction of the optimum design.

Additionally, the working principle of the impact energy scatterer is validated, for the first time, experimentally.

A test rig is designed and excellent agreement between the measurements and the numerical predictions is obtained.

It is demonstrated that local dissipation in the contact region is negligible, while a substantial amount of energy is scattered to high frequencies.

It is thus concluded that impact energy scatterers represent a promising vibration mitigation technology, as they can be designed to minimize inelastic material behavior in the contact region, while simultaneously providing excellent vibration reduction.