Self-Tuning Vibration Absorber Made with In-Vacuo Structured Fabrics

This paper presents a study on the design and implementation of a self-tuning beam-like vibration absorber. The beam element is fixed to a middle post and it is made by a scored structured fabric encased in a deflated plastic bag. The bending stiffness of this beam can be suitably varied by modulating the vacuum in the bag. In this way the resonant response of its flapping vibration resembles the dynamic of a mass-springer-damper absorber, whose fundamental resonance frequency can be duly adjusted by varying the level of vacuum in the bag. The paper presents an extensive experimental analysis of the tuning features and vibration control performance generated by a prototype absorber, which is fixed on a plate hosting structure excited by a brodband random disturbance. Two tuning principles are investigated: the first relies on on the so-called "global cost function" given by the minimisation of the plate total flexural kinetic energy; the second relies on the so-called "local cost function", which is based on the maximinisation of the vibration power absorbed by the flapping vibration of the beam-like element of the absorber.