An Efficient Simulation Strategy for The Design of Composite Acoustic Metamaterials

Simulations are promising to test acoustic metamaterials. Still, no ready-made simulation software is dedicated to the tests of acoustic metamaterials. FEM software is a reasonable choice since substructure-compounded acoustic metamaterials are analogous to mechanical systems. Then, challenges come from two main aspects: the way to process massive intermediate data and the effective mathematical model to build a vibro-acoustic environment. Therefore, simulation strategy designs considering efficiency and accuracy are needed. At the same time, the simulation strategy design and the acoustic metamaterial design are mutually dependent. The simulation strategy designs start with choosing the proper simulation software. And this paper chooses MSC Nastran 2020, MSC Actran 2020, and Abaqus 2020 (for convenience, they are called Nastran, Actran, and Abaqus in the following contents) as candidate software due to their distinctive characteristics. Specifically, Nastran is an expert in structure analyses but not competent in acoustic analyses. In contrast, Actran is an expert in acoustic analyses but not so efficient in structure analyses. In comparison, Abaqus is a Multiphysics analyser but not an expert in fluid or structural fields. And Actran’s data management capability is weak than Nastran and Abaqus. Finally, it is convinced that Nastran’s “ACMS Method” is the best in eigenvalue extraction analyses. Then, Nastran’s modal-space-based “Ordinary Method” is the best in steady-state-dynamic analyses of frequency-dependent models. At the same time, Nastran’s modal-space-based “ACMS Method” is the best in steady-state-dynamic analyses of non-frequency-dependent models. After that, Nastran’s eigenvalue extraction analyses with the “ACMS Method” cooperate with Actran’s modal-space-based analyses with the diffuse incident field is the best in vibro-acoustic analyses. The acoustic metamaterial designs start with a panel-like periodic structure. And its substructures (meta-atoms) are in a centre-mass-intensive form that consists of an aluminium cylindrical core and a melamine cubic base. The aluminium core is isotropic and non-frequency-dependent, while the melamine base is orthotropic and frequency-dependent. Then, based on the basic configuration, the size-controlled panels, the constrained-lateral-boundary-controlled panels, the aluminium-inclusion-controlled panels, and the layers-controlled panels are four derivatives that this paper sets as the preliminary acoustic metamaterial designs. The simulations’ task in this paper is to verify their low-frequency sensibility and soundproof capability. Finally, it is convinced that acoustic metamaterials are sensible in the low-frequency range (0-220Hz), and the sensibility is adjustable through the control parameters. At the same time, acoustic metamaterials’ soundproof capability is weaker than pure melamine foam and aluminium alloy. Fortunately, increasing the panel’s constrained lateral boundaries can significantly increase the material’s soundproof capability.