Attenuation and localization of bending waves in a periodic/disordered fourfold composite beam

By using the transfer matrix method this paper presents a study of the complex band structure, attenuation spectra and localization of bending waves in a periodic/disordered fourfold composite beam constructed by inserting thin piezoelectric or soft rubber layer at each interface of original elastic composite structures. Numerical examples are presented and the accuracy is validated by the wavelet method. The results show that the piezoelectricity can adjust the band gaps and the soft rubber can enlarge the degree of the localization and the frequency ranges of the complex band gaps. The localization factor resembles the shape of the attenuation curve in the complex band gaps. Subtle differences between the random disorder and the deterministic disorder are observed, except at lower frequencies. The behavior of the wave propagation and localization in random disordered beams can be altered by tuning different inserting position. The existence of piezoelectricity and/or soft rubber layers lends new insight into the vibration control of composite beams.