抄録
The tuned vibration absorber is a well-established vibration control device, which can be used to suppress a troublesome resonance or to attenuate the vibration of a structure at a particular forcing frequency. Two of the drawbacks of such a device, however, are that it can detune during operation because of changes in forcing frequency, or that there may be differences between the designed and in situ behavior. A variable stiffness element in the tuned vibration absorber can be used to maintain a tuned condition so that the natural frequency of the absorber can be adjusted with time. The mechanical properties of viscoelastic material, Young's modulus and loss factor in particular, change with temperature. Viscoelastic materials are then suitable candidates for the realization of adaptive tuned vibration absorbers, although their loss factor may be high. Viscoelastic materials have also the advantage to be cheap and common, and their manufacturing processes are well established. This paper presents an investigation on the use of viscoelastic materials as variable stiffiiess elements of tuned vibration absorbers. Both numerical and experimental investigations have been carried out. In particular, three different absorbers have been built with three different materials. The materials have been chosen so to show, at ambient temperature, glassy, transient and rubbery behavior respectively. The absorbers have been built in the shape of beams and heating pads have been attached to one side of the beam in order to control temperature. The best performing absorber showed a 27% change in the tuned frequency.
