A Hydro-Mechanical Vibration Absorber with Adjustable Operating Frequency

Unwanted resonances in industrial plants often result in unpleasant noise or may even end up in a reduced lifetime of mechanical structures and components. Such vibrations are often reduced by wellestablished vibration absorbers, which are designed and precisely tuned to one specific frequency. Furthermore, often the natural frequency of, for instance, a mechanical structure is not accurately known and must be identified by an experimental modal analysis. Another limitation of conventional single-frequency absorbers is that in some applications the frequency of the unwanted vibrations varies over lifetime, which reduces the effectiveness of the initially designed absorber. Moreover, in many cases the frequency of the undesirable vibration changes with the operating point of the plant, which requires the installation of multiple vibration absorbers with different operating frequencies. In this paper a new hydro-mechanical vibration absorber with a continuously adjustable operating frequency is presented, which eliminates the shortcomings mentioned above. In contrast to conventional absorbers the stiffness of the hydro-mechanical spring mass absorber is realized by a gas-loaded hydraulic capacitance, which depends on the mean operating pressure. The concept of the presented absorber is investigated theoretically and validated by simulation experiments. The results are discussed in detail and an outlook on further steps in development is provided.