Directional acoustic cloaks that conceal an aluminum cylinder for airborne sound waves are presented in this paper. Subwavelength cylindrical aluminum inclusions in air constitute the cloak design to aid practical realizations. The positions and radii of the subwavelength cylinders are determined by minimizing scattering from the cloak-structure and cylinder using the gradient-based topology optimization method. In the final optimization step, the radii of the subwavelength cylinders are constrained to three discrete values. A near-perfect narrow-banded and angular cloaking effect is obtained by optimizing for one target frequency. To get a larger bandwidth, the acoustic cloak is optimized for three frequencies at the cost of reduced peak cloaking performance at the center frequency.
Topology Optimized Cloak for Airborne Sound
Contributed by the Design Engineering Division of ASME for publication in the JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received April 30, 2012; final manuscript received September 7, 2012; published online June 6, 2013. Assoc. Editor: Mahmoud Hussein.
Andkjær, J., and Sigmund, O. (June 6, 2013). "Topology Optimized Cloak for Airborne Sound." ASME. J. Vib. Acoust. August 2013; 135(4): 041011. https://doi.org/10.1115/1.4023828
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