Optimisation of a Multi-Material Acoustic Black Hole

Acoustic black holes (ABHs) have been proven as an effective passive vibration control measure. Typically, they are realised by introducing a geometric taper into the structure. This approach introduces thin structural sections which leaves the ABH prone to damage through fatigue. An alternative approach has been suggested in which the material properties vary within the structure, which can be realised through multi-material additive manufacturing. This allows the structure to maintain a constant thickness and this may reduce the effect of fatigue. Prior work has been performed to characterise the materials currently available that would be suitable for the ABH application. This paper investigates methods of optimising the design of the multi-material ABH, in order to minimise the reflection coefficient in a beam termination application.