scholarly journals Soft resonator of omnidirectional resonance for acoustic metamaterials with a negative bulk modulus

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Xiaodong Jing ◽  
Yang Meng ◽  
Xiaofeng Sun
Keyword(s):  
Bulk Modulus ◽  
Acoustic Metamaterials

scholarly journals Flute-model acoustic metamaterials with simultaneously negative bulk modulus and mass density

2013 ◽  
Vol 173 ◽  
pp. 14-18 ◽  
Author(s):  
Hong-Cheng Zeng ◽  
Chun-Rong Luo ◽  
Huai-Jun Chen ◽  
Shi-Long Zhai ◽  
Chang-Lin Ding ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Mass Density ◽  
Acoustic Metamaterials

Design of Acoustic Metamaterials for Cabin Noise Reduction and Pressure Sensing in Propfan Aircrafts

2020 ◽  
Author(s):  
Asarudheen Abdudeen ◽  
Jaber Abu Qudeiri ◽  
Aiman Ziout ◽  
Thanveer Ahammed
Keyword(s):  
Bulk Modulus ◽  
High Efficiency ◽  
Acoustic Metamaterials ◽  
Pressure Sensing ◽  
Acoustic Metamaterial ◽  
Helmholtz Resonators ◽  
Cabin Noise ◽  
Main Challenge ◽  
Open Rotor ◽  
Passenger Cabin

Abstract This research is about to address the main challenge related to newly emerging airplane engines, namely open rotor (propfan). Though these engines show high efficiency, yet the noise generated is very high. This research focuses on designing a new class of ‘Acoustic Metamaterial’ to overcome the noise reaching the passenger cabin. An acoustic metamaterial is a complex composite structured material that exhibits negative density and negative bulk modulus either individually or simultaneously. The objective of this research is to design an acoustic fuselage using a combination of Negative density acoustic material (NDAM) and Negative bulk modulus acoustic material (NBAM) to reduce the noise transmission into the passenger cabin. Furthermore, the developed acoustic metamaterial structure can be used for pressure sensing application. Based on the literature reviews, experiments pertaining to the combination of NBAM and NDAM are limited. Hence, an integration of both structures is very appealing to be developed. Accordingly, the research will design a combination of two types of Helmholtz resonators (Conventional with one inner membrane and two inner membranes) of negative bulk modulus acoustic metamaterial. This filter can be embedded in a sandwich structure to obtain a new type of cabin wall. Hence the design and development of such acoustic metamaterial are expected to reduce the noise inside the cabin to a minimum. Also, the designed structure will be able to sense pressure at selected locations inside the cabin.

Active Acoustic Metamaterial With Simultaneously Programmable Density and Bulk Modulus

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
W. Akl ◽  
A. Baz
Keyword(s):  
Wave Propagation ◽  
Bulk Modulus ◽  
Material Properties ◽  
Variable Stiffness ◽  
Lumped Parameter Model ◽  
Propagation Path ◽  
Cylinder Wall ◽  
Acoustic Metamaterials ◽  
The Face ◽  
Propagation Pattern

Acoustic metamaterials are those structurally engineered materials that are composed of periodic cells designed in such a fashion to yield specific material properties (density and bulk modulus) that would affect the wave propagation pattern within in a specific way. All the currently exerted efforts are focused on studying passive metamaterials with fixed material properties. In this paper, the emphasis is placed on the development of a new class of composite one-dimensional active acoustic metamaterials (CAAMM) with effective densities and bulk moduli that are programmed to vary according to any prescribed patterns along its volume. A cylindrical water-filled cylinder coupled to two piezoelectric elements form a composite cell to act as a base unit for a periodic metamaterial structure. Two different configurations are considered. In the first configuration, a piezoelectric panel is flash-mounted to the face of the cylinder, while the other is side-mounted to the cylinder wall, introducing a variable stiffness along the wave propagation path. In the second configuration, the face-mounted piezoelectric panel remains unchanged, while the side-mounted panel is replaced with an active Helmholtz resonator with piezoelectric base panel. A detailed theoretical lumped-parameter model for the two configurations is present, from which the stiffness of both active elements is controlled via charge feedback control to yield arbitrary homogenized effective bulk modulus and density over a very wide frequency range. Numerical examples are presented to demonstrate the performance characteristics of the proposed. The CAAMM presents a viable approach to the development of effective domains with a controllable wave propagation pattern to suit many applications.

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