Soft solid subwavelength plates with periodic inclusions: Effects on acoustic Transmission Loss

Dispersion and scattering properties of a soft solid plate with solid cylindrical inclusions embedded in are theoretically and numerically reported in this work. The system is numerically analyzed considering both the vibroacoustic coupling and the presence of viscoelastic losses. In addition to the mechanical properties of the soft solid plate that allows the shift of the higher order Lamb modes to the low audible frequency domain, the presence of the inclusions introduces resonant and antiresonant phenomena in the subwavelength regime, leading to an elastic band-gap and a destructive modal interference in the soft solid plate able to interact with each other. These phenomena are used to design a system with strong transmission loss, breaking the mass law by 15 dB, and with subwavelength dimensions as the thickness is 32 times smaller than the equivalent wavelength in air. These performances are both computed and tested experimentally using a standard measuring process.