The influence of random microstructure on wave propagation through heterogeneous media

In this thesis the influence of mechanical and geometrical properties of a heterogeneous periodic composite material (in 1D and 2D), both deterministic and stochastic in nature, on wave propagation has been analysed from the position of stop band phenomenon.

Numerical analyses have been used to identify those parameters that have the most significant effect on the wave filtering properties of the medium. The study has started on a 1D periodic laminate material. Further, a randomness has been added into the material’s properties in order to study its influence on the stop band. The stop band phenomenon has also been studied on the material in a 2D case, first with periodic microstructure, then with randomness added into the microstructure to test its influence on the stop band. Special attention has been given to the prediction of the first stop band frequency with numerical analysis of an explicitly defined heterogeneous structure compared and confirmed by results obtained using gradient theory and analytical derivations.