Observation of trampoline phenomena in 3D-printed metamaterial plates

Two dimensional phononic metamaterials, consisting of plates with resonant cylinders have been shown to attenuate waves much larger than their characteristic unit cell size by opening subwavelength band gaps. However the bandwidth of the gap correlates strongly with the resonator mass, which limits metamaterials functionality in mass sensitive applications. Trampoline phenomena have theoretically been shown to broaden the width of the first partial band gap by up to a factor 4 of the linear, resonant band gap. In this work, we provide an experimental demonstration of the trampoline phenomena in 3D-printed plates, consisting of pillars and holes, composed of a single material. We observe the opening of significant locally resonant band gaps, ≈ 30% normalized width, without adding any significant mass to the homogeneous plate. We show numerically and experimentally that trampoline plates increase both partial and full band gaps width, while reducing the base-plate's mass by ≈30% in the studied configurations.