## Abstract

It has been shown in several recent publications that acoustic materials consisting of periodic arrangements of resonators can render high absorption coefficient values while maintaining compactness. This makes them attractive solutions for applications in which low frequency sound control is needed, and/or when there are significant space constraints. Nevertheless, the acoustic performance of these surfaces varies with the angle at which a wave impinges on the surface, and there are several applications for which a consistent angle-dependent behaviour is beneficial. Density-based topology optimization is a tool that can help realize designs with a large degree of geometrical freedom. Using this framework we have designed a structure that reduces the sensitivity

of the performance of a periodic array of a 2D Helmholtz resonator to changes in the incidence angle. By combining different geometrical features, the optimized structure can extend the range of angles for which absorption coefficient values above 0.95 can be achieved, which spans from 0

of the performance of a periodic array of a 2D Helmholtz resonator to changes in the incidence angle. By combining different geometrical features, the optimized structure can extend the range of angles for which absorption coefficient values above 0.95 can be achieved, which spans from 0

^{◦}to 47.5^{◦}for the initial surface, to the range from 0^{◦}to 60^{◦.}Original language | English |
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Title of host publication | Proceedings of Inter-noise 2021 |

Number of pages | 12 |

Publication date | 2021 |

Publication status | Published - 2021 |

Event | 50^{th} International Congress and Exposition on Noise Control Engineering - Virtual congress, Washington, United StatesDuration: 1 Aug 2021 → 5 Aug 2021 |

### Conference

Conference | 50^{th} International Congress and Exposition on Noise Control Engineering |
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Location | Virtual congress |

Country/Territory | United States |

City | Washington |

Period | 01/08/2021 → 05/08/2021 |