Abstract
In this paper, we propose a novel porous metamaterial structure with an improved acoustic energy absorption performance at high-temperature and in the low-frequency range. In the proposed novel porous metamaterial structure, a porous material matrix containing periodically perforated cylindrical holes arranged in a triangular lattice pattern is applied, and additional interlayers of another porous material are introduced around these perforations. The theoretical model is established by adopting the double porosity theory for the interlayer and the cylindrical hole which form an equivalent inclusion and then applying the homogenization method to the porous metamaterial structure formed by the equivalent inclusion and the porous matrix. The temperature-dependent air and material parameters are considered in the extended theoretical model, which is validated by the finite element results obtained by COMSOL Multiphysics. The acoustic or sound energy absorption performance can be improved remarkably at very low frequencies and high temperature. Furthermore, the underlying acoustic energy absorption mechanism inside the unit-cell is investigated by analyzing the distribution of the time-averaged acoustic power dissipation density and the energy dissipation ratio of each constituent porous material. The results reveal that regardless of the temperature, the acoustic energy is mostly dissipated in the porous material with a lower airflow resistivity, while the acoustic energy dissipated in the porous material with a higher airflow resistivity also becomes considerable in the high-frequency range. The novel porous metamaterial structure proposed in this paper can be efficiently utilized to improve the acoustic energy absorption performance at high temperature.
Highlights
Energy-absorbing materials and structures [1,2,3] are widely used in engineering applications to provide an adequate mechanical or thermal protection [4] and reduce harmful noises [5,6,7,8]
The acoustic or sound energy absorption characteristics of the proposed porous metamaterial structure and the underlying physical mechanism are studied in detail
The proposed novel porous metamaterial structure consists of a porous material as matrix, periodically perforated cylindrical holes in a triangular lattice pattern, and another porous material as interlayers between the matrix and the perforated cylindrical holes
Summary
ACTA MECHANICA SOLIDA SINICA randomly distributed micro-pores are highly effective for mechanical and acoustic energy absorption. Conventional porous materials only have an effective sound energy absorption performance with a quite large bandwidth at relatively high frequencies in general For improving their low-frequency absorption capability, in the past few decades, scientists began to work on the double porosity materials which have two interconnected pores of very different characteristic sizes. The introduction of additional interlayers consisting of another porous material around the perforations aims to form a novel porous metamaterial or composite structure by combining the advantages of the two different constituent porous materials (inner porous material interlayer and outer porous material matrix) and to obtain an improved sound energy absorption performance at high temperature, in the low-frequency range and with a sufficiently large bandwidth. A theoretical model for the proposed novel porous metamaterial structure is established, and its sound energy absorption characteristics are analyzed by taking the temperature-dependent air and material parameters into consideration. Some conclusions are drawn, which are relevant for the design, optimization and application of the proposed novel porous metamaterial structure at low frequencies and in the high-temperature environments
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