Experimental evidence of the Poisson-like effect for flexural waves in thin metallic plates

This Letter reports the feasibility of a structure specifically designed for the control of flexural waves propagating in thin perforated plates. The structure, here denominated as a redirector device, consists of a square array of free holes that splits the impinging beam and transmits sideways their vibrational energy. This behavior is known as a Poisson-like effect, and it was theoretically described in different acoustic structures. This effect is experimentally demonstrated for flexural waves excited in an aluminum perforated plate, and it is explained in terms of a physical mechanism different to that reported for acoustic waves interacting with thin hollow cylinders embedded in water. In addition, a collimator device based also in free holes is designed and validated with the purpose of providing the beam impinging the redirector device. The measurements indicate that the amount of redirected energy is strongly enhanced when a barrier of two-beam resonators is added at the rear side of the redirector. All the designs are validated by an experimental setup employing 1 mm thick aluminum plates.