This experimental study was conducted for the purpose of enhancing vibration suppression in periodically excited flexible structures by using model predictive control (MPC), an advanced optimal-control method that can be used to handle system constraints at all sampling steps. The Hildreth optimization solver was used to examine two MPC strategies, a basic MPC strategy and a repetitive MPC (RMPC) strategy, and the active vibration-control design and performance of the strategies were evaluated. The disturbance-rejection performance of the applied MPC methods was specifically investigated by using periodic input signals to excite a piezoelectric flexible beam. These comparative studies performed together with parameter analysis offer a design guideline for achieving satisfactory vibration-suppression performance and further demonstrate that the applied RMPC method can effectively suppress the vibration of a flexible-structure system.