UNIT CELL AND STRUCTURAL PANEL ASSEMBLIES WITH ENHANCED IMPACT AND NOISE ABSORPTION CHARACTERISTICS

A structural panel assembly including an array of unit cell assemblies. Each unit cell assembly includes: an outer frame member spaced apart from an inner frame member; a plurality of quasi-zero stiffness (QZS) spring members disposed between the inner frame member and the outer frame member; a phononic crystal disposed between the inner frame member and the outer frame member; and a plurality of locally-resonating phononic crystals (LRPC) spring members disposed between the phononic crystal and one or more of the inner frame member and the outer frame member. The phononic crystal acts as a scattering phononic crystal (SPC) for attenuating high-frequency sound waves within the unit cell assembly and as a vibrating mass for the LRPC spring members for attenuating low-frequency sound waves within the unit cell assembly by converting the low-frequency sound waves to heat by vibration.