In this paper, we have built some new composite sandwich platbands with different core (made of  polypropylene honeycomb and polystyrene) and different reinforcement (glass-fiber, carbon-fiber and steel wire mesh). Starting from the dynamic response of these sandwich beams with damping, that are in free vibration, we have established a way to determine the damping factor. We have experimentally determined the damping factor per unit mass for the beams and the stiffness.