Pneumatic soft phononic crystals with tunable band gap

• A pneumatic soft phononic crystal with tunable band gap is computationally designed. • The band gap evolution law of the soft phononic crystals controlled by the air pressure is explored. • The influence of three geometric parameters of phononic crystals on the band gap is studied. Tuning the band gap by mechanically generating deformation of soft phononic crystals provides an effective means to manipulate the propagation of acoustic waves. In this paper, a pneumatic soft phononic crystal is computationally designed to realize tunable band gap. It consists of a line of soft inflatable silicone cylinders surrounded by air. In detail, there is no band gap in the soft phononic crystal when it is unpressurized. By applying the air pressure, the scatterer in the soft phononic crystal is deformed, then a new reversible band gap appears in the phononic crystal. By adjusting the air pressure, the opening and closing of the band gap can be controlled. In addition, the width of the band gap can be tuned by the application of air pressure. We obtained the mechanical parameters of the rubber-like material from the experimental data. On this basis, the variation of the band gap of phononic crystals with applied different air pressures to the soft scatterer is investigated numerically. The effect of scatterer geometry on the band gap evolution of phononic crystals is also parametrically studied. Compared with traditional mechanical deformation means, such as tension and compression, the pneumatic manipulation is low-cost, fast in response and easy to integrate. This work introduces a feasible design of tunable soft phononic crystals.