Lightweight waveguide absorbers based on spiral acoustic black holes for reducing structural vibrations in mechanical systems

We present an ABH-based solution to address challenging industrial problems related to structural vibration and vibration-induced noise. To tackle those problems, we utilize lightweight waveguide absorbers (WGAs) based on spiral acoustic black holes (ABHs). The WGA is designed by combining a spiral acoustic black hole with a rod to absorb flexural waves and dampen the vibrations in dynamic systems. The WGAs are customized to industrial needs, pursuing both high-damping performance and lightness. Specifically, we design non-identical configurations of WGAs by taking multiple or broadband target frequency ranges into account. We then determine optimal attachment positions and directions of the designed WGAs while considering constraints on installation space and total weight of WGAs. Numerical and experimental results verify the feasibility to meet the requirements of industries through the use of WGAs, thereby opening up the possibility of practical applications to real-world problems.