Random vibrations of viscoelastic laminated plates

The response of viscoelastic laminated plates subjected to random excitation is investigated. The Fourier transform of the Boltzmann representation of the viscoelastic phases is incorporated into a micromechanical analysis, which establish the five frequency-dependent functions, characterizing the effective behavior of unidirectional fiber composites. This enables to express the governing equation, using the first-order shear deformation theory, in the frequency domain. The inversion of the response function into the time domain is performed by the Fast Fourier Transform algorithm. Two stationary random fields are considered: (i) ideal white noise, and (ii) band-limited white noise. In both cases analytical expressions for the mean squares are derived. Furthermore, the complex eigenvalues are investigated and the ratio between the imaginary part and the real one, η, is shown to relate to the damping ratio. The influence of the temperature, length-to-thickness ratio, and the fibers’ orientation on η is studied.