Feasibility of nonlinear absorbers for transient vibration reduction

Torsional vibrations are a cause of severe damage to flexible couplings and gearboxes of a dredger drive line. In this paper the feasibility of three different vibration absorbers is discussed when reducing transient vibrations originating from sudden load changes. The classical linear absorber is compared to two nonlinear ones, one with a cubic spring (known as the nonlinear energy sink or NES) and one with a combination of a linear and a cubic spring (a Duffing type absorber). Both nonlinear absorbers succeed in achieving a multimodal vibration reduction, whereas the linear absorber can only mitigate a single vibration mode. The most important reduction is however obtained in the initial phase where the energy of one vibration mode is decreased through a beating phenomenon. A much slower energy reduction of the remaining vibration modes takes place after this initial phase. As a result, both the NES and the Duffing type absorber still need to be tuned to the most important mode, despite their ability to mitigate multiple modes.