Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Transmission loss of decorated membrane resonators panels using modal-based numerical methods: a comparison
Submission Author:
Pedro Cerântola , SP
Co-Authors:
Pedro Cerântola, Laurent Maxit, Leopoldo de Oliveira
Presenter: Pedro Cerântola
doi://10.26678/ABCM.COBEM2021.COB2021-1343
Abstract
The always-increasing demand for energy efficiency in vehicles and machines inevitably drives designs towards lightweight structures, posing a challenge for noise and vibration. The difficulties are even greater if passive control is needed to address the low-frequency range, which will often lead to heavy and bulky solutions. Having the capability of outperforming the mass-law of acoustics, Membrane Acoustic Metamaterials (MAM) have been recently studied in panel configurations as a potential lightweight solution for sound insulation in the low-mid frequency range. MAM are realised by a stretched membrane over a regular frame, resulting in a arrangement that tessellates the plane. Decorated Membrane Resonators (DMR) are the most commonly MAM setting employed, with a concentrated mass added to the unit cells. At the present time, most of the research made focuses on analysing the behaviour of unit cells rather than the full metastructure, mainly due to computational costs. If deeper and more practical investigations are to be exploited, methods other than the direct approach – commonly used in finite elements modelling environments – should be validated. To tackle such a challenge, this paper studies the efficiency and accuracy of two techniques for predicting the Transmission Loss (TL) of a MAM metapanel separating two acoustic cavities: the Dual Modal Formulation (DMF) and the Statistical Modal Energy Distribution Analysis (SmEdA). While the former is based on modal expansions considering the uncoupled-blocked modes for the cavities and the uncoupled-free modes for the panel, the latter consists of an extension of the well-known Statistical Energy Analysis (SEA) method that relaxes the modal energy equipartition assumption. The two approaches are based on the same subsystem modes but they differ by the resolution: DMF condensates the modal participation factors of the non-excited subsystems while SmEdA establishes the power balance equations between the subsystem modes by using a formulation for two coupled oscillators. Aside TL, a comparison is made over the computational cost associated with both methods for the solving of the vibro-acoustic problem we propose.
Keywords
Membrane acoustic metamaterials (MAMs), Dual modal formulation (DMF), Statistical modal energy analysis (SmEdA), Transmission Loss, Decorated membrane resonator (DMR), Low-mid frequency modelling
