Numerical investigation of the potential of tailored inclusions as noise reduction measures

F Mittermeier,M Miksch,J Schauer,G Müller

doi:10.1088/1742-6596/1264/1/012013

F Mittermeier, M Miksch + Show 2 more

Open Access

https://doi.org/10.1088/1742-6596/1264/1/012013

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Abstract

The reduction of noise and vibrations is an important task in automotive and aircraft industry. Various applications require slender or adjustable reduction measures. Metamaterials formed by a periodic assembly of unit cells consisting of non-homogeneous material decomposition and having topology dependent favorable absorption properties can meet this need. The absorption efficiency of different types of metamaterials has already been proven by various authors. Thereby metamaterials formed by a periodic assembly of tuned mass dampers on plate-like structures or porous layers with rigid inclusions have been investigated. Beyond that, we suggest to design metamaterials consisting of inclusions containing appropriately tuned mass dampers embedded in a material layer and to examine their noise reduction potential. It is investigated, whether besides absorbing energy by exciting the damping device, the orientation of the tuned mass damper is active by purposefully deflecting waves inside the structure. The analysis is carried out applying the Wave Finite Element Method. Using the inverse approach of the Wave Finite Element Method, stop bands, i.e. frequencies for which no free wave propagation is observed, are detected. In a parameter study, the influence of the characteristics of the inclusion on the absorption behavior of the metamaterial is determined.

Highlights

Diverse applications in automotive and aircraft industry require slender noise and vibration reduction measures
Investigating the influence of the inclusion shape and the tuned mass dampers (TMDs) alignment on the dispersion characteristics of the observed metamaterial with tailored inclusions leads to the following conclusions:
For the geometry and material configurations applied within this contribution, the stop band width tends to increase with an increasing variance of the mass distribution

Summary

Introduction

Diverse applications in automotive and aircraft industry require slender noise and vibration reduction measures. By appropriately shaping the unit cell, so called stop bands, being frequencies where no free wave propagation occurs, can be observed. Besides performing numerical simulations, the results were confirmed experimentally Beyond that, this contribution investigates, whether embedding inclusions containing TMDs in a material layer will effectively increase the noise reduction potential of periodic metamaterials. The influence of the inclusion shape as well as of the TMD orientation on the wave propagation in the periodic structure are studied carrying out numerical simulations using the Wave Finite Element Method (WFEM). The solid part of the unit cell is made of aluminum; the material properties are specified in table 1

Density ρ

Inclusion area A

The average mass distribution can be determined as ρ

Circle Rectangle Rhombus

TMD and with which is inclined by φ

Conclusion and outlook