Quasi-perfect spiral sound-absorbing metasurfaces for ultra-broadband motor vibration and noise reduction

Effectively reducing motor vibration and radiated noise is a highly challenging technical problem, especially under complex multi-physics coupling conditions. This paper proposes a novel design strategy involving a rubber-embedded quasi-perfect spiral acoustic metasurface to effectively reduce motor vibration and radiated noise. When the spiral metasurface is combined with rubber, it is equivalent to a mass-spring system. When the motor’s vibration frequency matches the natural frequency of the structure, the system undergoes resonant absorption, significantly reducing the vibration amplitude. Simultaneously, the spiral metasurface can redistribute the phase of sound waves and extend the sound wave path, causing opposite response modes on the upper and lower surfaces, achieving complete sound absorption at specific frequencies. This method is not affected by the motor’s operating conditions and can achieve vibration and noise reduction in specific frequency bands by adjusting parameters such as spiral path length, order, and rubber thickness. The structure’s thickness is only one-tenth of the motor’s diameter. Numerical results show that embedding just two spiral metasurfaces in the damping rubber can reduce the radiated noise by an average of 6 dB, decrease the relative vibration amplitude peak by 0.99, and achieve a frequency band attenuation rate of over 80%. This method provides a new solution for ultra-broadband vibration and noise reduction in motors and lays the foundation for similar designs in complex rotating machinery.