Shear thickening fluids (STF) demonstrate the ability to simultaneously stiffen and increase their damping capacity above a critical shear strain, which depends on the particle concentration and aspect ratio in the STF. The present work considers two types of STF differing by their particle size distribution: one is monodisperse and the other one is based on aggregates. The focus is on the ability to model and predict the behaviour of sandwich structures containing these fluids at confined interfaces. The rheological properties of the STF are first measured as a function of strain and frequency. Damping characteristics of model sandwich beams are then measured, and a finite element model using Timoschenko beams is proposed to predict the flexural compliance of the beams as a function of frequency. The model uses the strain-and frequency-dependent values of elastic and storage shear moduli of the suspensions. Good agreement is obtained, indicating that this approach could possibly be used as an inverse method to determine the rheological properties of STF beyond the range of the usual rheometers.