A new method for modeling and designing passive fluidic flexible matrix composite (F2MC) vibration treatments is presented. F2MC tubes are attached to a structure and connected to a fluidic circuit that acts similar to a tuned mass damper. The model couples the structural and fluidic domains through finite element degrees of freedom that axially deform the F2MC tubes. To demonstrate this method, a simple finite element model of a 1/3 scale helicopter tailboom is developed and used to assess two treatment concepts for a coupled bending-torsion vibration mode. With proper tuning of the fluidic circuit, reductions on the order of 80% can be achieved in the resonant amplitudes of tailboom tip bending and twisting vibrations. The model predicts that these levels of vibration reduction can be achieved using F2MC tubes mounted at the root of the tailboom with various tube lengths and circuit parameters. These results indicate that there is significant flexibility in the design of these promising lightweight and compact vibration treatments.