SBIR-STTR Award

Acoustic bandgaps are frequency domains where the propagation of sound and phonons is forbidden. In the last few years, significant advances have been made, mostly in Europe in the area of theoretical characterization of these materials and devices. Experimental configurations have focused on materials with specific 2-D and 3-D internal geometries which exhibit bandgap properties. It is possible, therefore, to make a device with an intricate internal geometry using free form fabrication techniques. The proposed effort is aimed at developing theoretical models for the design and performance prediction of the acoustic bandgap (ABG) materials and devices, leading to the fabrication and testing of a prototype that exhibits acoustic bandgap properties. During Phase I, an analytical design tool for the design and performance prediction of an ABG device will be developed, modifying codes that have been successfully employed in past research. By the end of Phase I, a prototype will also have been fabricated and characterized. During Phase II, specific vibration isolation applications will be targeted for insertion of the ABG device technology. In addition, the design tool will be refined.

Keywords:
Acoustic, Bandgap, Internal Geometry, Solif Freeform, Fabric

Acoustic Bandgap (ABG) materials can serve as acoustic filters to reduce and/or modify acoustic signatures. This is made possible by the incorporation of specific internal geometries within ABG panels, that are produced using solid free form fabrication techniques. Three different types of (ABG) materials are presented, with two selected for further investigation. Two specific applications are presented: the first is in the area of noise suppression for machinery on the Advanced Amphibious Assault Vehicle, and the second is a scheme for flow separation control in jet engines. The work plan presented includes computer analyses, the development of a refined design tool, design, fabrication and testing of various configurations of ABG materials, and the development of tunable ABG materials. The Phase II effort is geared primarily towards development of ABG materials and devices for the two applications that have been identified.

Keywords:
Acoustics; Bandgap; Solid Freeform Fabrication; Vibration; Acoustic Signature; Noise Reduction;