Design of passive directional acoustic devices using Topology Optimization - from method to experimental validation

Area of Science:

• Acoustics
• Mechanical Engineering
• Computational Physics

Background:

• Designing acoustic devices for directional sound emission is challenging, especially at frequencies near the acoustic wavelength.
• Traditional designs like parabolic reflectors have limitations in directivity and side-lobe suppression.

Purpose of the Study:

• To develop a topology optimization method for designing efficient acoustic focusing devices.
• To tailor the sound emission pattern of acoustic sources across a specific frequency band.
• To validate the performance of optimized devices against classical designs.

Main Methods:

• Topology optimization was employed to design acoustic focusing devices.
• Numerical simulations were conducted for two-dimensional directional sound emission.
• Experimental validation was performed using three-dimensional printed optimized designs.

Main Results:

• Optimized devices achieved at least 15 dB on-axis level difference compared to off-axis directions over octave frequency bands.
• Devices were successfully designed for dimensions comparable to the acoustic wavelength and for higher frequencies.
• The proposed method's designs outperformed parabolic reflectors in directivity and side-lobe levels.

Conclusions:

• Topology optimization provides a robust method for designing high-performance acoustic focusing devices.
• The designed devices offer significant improvements in directional sound emission and operate effectively across broad frequency ranges.
• The method ensures performance robustness against geometric production errors by incorporating design perturbations.