Our group possesses extensive knowledge on the modeling of wave propagation in solids and of fluid structure interaction (FSI). We use analytical and numerical modeling to better understand the processes that govern the propagation of elastic waves in solids with complex geometries and the exchange of energy at interfaces. The models lead to engineered materials represented by periodic arrangements of features in space (metamaterials, phononic crystals), aperiodically microstructured materials (such as inspired by quasicrystals) or other complex, inhomogeneous materials, such as foams, or compacted granular materials. We experimentally verify and complement our models using scanning laser vibrometry, impedance analysis as well as our acoustic measurement set-ups. This combination of models and experimental insights improves the properties of everyday structures and achieves novel functionalities.