The active control of vibrations of composite beams by parametric stiffness modulation.
An active control of resonant vibrations of composite beams, performed by a parametric stiffness modulation, is considered. A sandwich beam composition with the continuous core is taken as a model. The stiffness modulation is introduced by some fairly small changes in orientations of elements of the microstructure of the core ply. The controlled vibrations are of dominantly flexural type excited by a transverse force acting at a low resonant frequency, whereas the stiffness modulation is performed at a comparatively high frequency identified by the resonance of a mode of dominantly shear type. This difference in time scales of the controlled vibrations and the input signal facilities makes a possible the direct partition of motion that predicts an existence of modal interaction between low-frequency and high-frequency motions due to so-called vibrational forces. It is shown that such a parametric control can provide a significant favourable shift of the first eigenfrequency of a controlled beam from its nominal value for an uncontrolled beam. Heavy fluid loading conditions are accounted for as well as material losses in structure. Then, instead of analysis of eigenfrequencies, a problem of forced vibrations is posed, and the forced frequency-amplitude response is analysed. It is demonstrated that, although heavy fluid loading reduces resonant frequencies of forced vibrations, the suggested mechanism of control remains valid in these cases.
scientific article; zbMATH DE number 1547860