Design of a multi-material acoustic black hole using geometric profile mapping

Austin, Beth and Cheer, Jordan (2024) Design of a multi-material acoustic black hole using geometric profile mapping. In Inter-Noise and Noise-Con Congress and Conference Proceedings. pp. 8489-8498 . (doi:10.3397/IN_2024_4102).

Record type: Conference or Workshop Item (Paper)

Abstract

Since their inception, acoustic black holes (ABHs) have taken on many forms. A wide range of profiles has been investigated for beam termination applications, including power laws and cosine profiles. However, all of these configurations have a common issue- the profiles have an inherent thin section at the end of the beam. This makes the profile susceptible to damage towards the tip, particularly through fatigue. Multi-material ABHs have been proposed as an alternative solution, maintaining a constant external geometry whilst varying the material properties along the length of the ABH termination. Previous work on multi-material ABHs has focused on optimising section lengths of each material based on a cost function, namely kinetic energy in the host beam. This work investigates the performance of multi-material ABH designs with section lengths chosen to approximate the effective impedance change of a range of geometric ABH terminations. The relative performance of each discretised gradient is compared through simulation in addition to comparison to an equivalent continuous gradient.

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