Off-axis directional acoustic wave beaming control by an asymmetric rubber heterostructures film deposited on steel plate in water

We numerically report a design of an off-axis directional beaming of acoustic wave, by placing a point acoustic source near the surface of an asymmetrical rubber heterostructures film deposited on steel plate in water. The rubber heterostructures film at left side and right side are constructed by alternately stacking rubber-1 and rubber-2 film periodically with different width percentages. The mechanism of the off-axis directional beaming is due to the surface acoustic resonances asymmetrically modulated by elastic properties of the rubber heterostructures. The deviation beaming angle is determined by the difference between the width percentages of rubbers in left and right side. The structure would have potential applications on a variety of acoustic compacted devices, such as non-destructive testing of materials, medical ultrasound instrumentation and etc.