Saturated Metallic Foam of Controlling Sound and Vibration
Abstract
Saturated Metallic Foam of Controlling Sound and VibrationFor decades, the design community has been searching for optimal materia""ls that control sound and vibration. Currently available polymers and naturally occurring rubbers suffer from severe disadvantages,"" such as the following: 1) relatively low levels of energy absorption, 2) lack of control over material properties, 3) significant w"eight and 4) strong dependence on temperature.A hypothesis of the proposed work is that metallic foams may be used as a host material to create a new class of metamaterials that overcomes these disadvantages. Metallic foams are now commercially available and are" typically made of aluminum, copper, or steel. They arelightweight but strong and have a relatively high stiffness. Previous work b"y others indicates thatthey are difficult to fracture. The proposed work will investigate four design parameters of metallic foam t"hat may be exploited to control sound and vibration. The first of these is pore density, typically measured as the number of pores p"er inch. Porosity describes the topology of the foam microstructure and alters the effective elastic moduli of the foam. The second" is voidfraction, which is the volume fraction of air in a cube of foam and controls the effective density of the foam. The third d""esign parameter is plastic deformation. After a foam is manufactured, plastic deformation will substantially modify the Poisson s ra"tio of the foam by changing the topology of the microstructure. Plastic deformation has previously been shown by others toproduce b"road ranges of Poisson s ratio, including negative values. The fourth design parameteris a fluid that saturates the metallic foam."" This saturation is possible due to the open cell microstructure. When the foam experiences sound or vibration, the saturating fluid" is forced into oscillating flow through the metallic microstructure of the foam. This oscillating flow will absorb significant ener"gy, thus reducing sound and vibration. To our knowledge, this fourth characteristic has never been investigated. A host of complemen"tary analytical and experimental investigations are proposed to understand the interactions between these characteristics and to derive a design methodology for choosing characteristics to optimally control sound and vibration.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 07, 2017
- Source ID
- N000141712685
Entities
People
- J. Gregory Mcdaniel
Organizations
- Boston University
- Office of Naval Research
- United States Navy