Simultaneous supply of infinite and infinitesimal stiffness of active isolation systems that are exposed to multiple vibration sources

Abstract

Commonly, vibration isolation systems reduce the transmissibility from seismic base vibrations to sensitive structures. To obtain a desirable low isolation frequency, vibration isolation systems are typically equipped with low stiffness interfaces between the involved structures. Strongly detrimental influences to the possible vibration reduction performance are caused by the effects of additional force disturbances that act directly on the isolated object. To protect sensitive structures from vibrations, isolation systems need to generate high flexibility against the vibrating ground. In the same time those systems need to generate high stiffness against the direct (force) disturbances as well. The technique described in this paper enables vibration reduction at such a sensitive object while seismic base and direct force disturbances are concurrently present. It is theoretically introduced and experimentally examined how the emerging conflict of simultaneous vibration isolation and energy reflection can be solved at a single isolation interface. This paper shows that even soft, adaptively altered isolation interfaces can reach these contrary goals. These interfaces are equipped with piezoelectric foil actuators to enable active control. The used active control mechanism and the very promising experimental results are highlighted in this paper.