Server Fan Noise Attenuation and Frequency Tuning via Planar Auxetic Metamaterials With Helmholtz Resonator

Abstract This study modeled a ventilation-type acoustic metamaterial based on planar auxetic metamaterials combined with Helmholtz resonators (PAMHR). The coupling between the resonators enables tuning the resonance frequency, and the integrated planar auxetic design enables coupling control across large arrays of Helmholtz resonators. This modular structural design achieved 45% ventilation and millimeter-scale dimensions. The PAMHR was found to perform well in theoretical analyses, numerical simulations, and experiments. PAMHR does not require complex external mechanisms to deform the resonators; instead, it relies on coupling effects to tune the structural resonance frequency. The tunable resonance frequency range exceeded 200 Hz, and its thickness is only 1/15 of the operating wavelength. When installed in a server, PAMHR effectively reduces fan noise and enhances hard drive performance by 25%, validating its added value in practical engineering applications and offering innovative insights into the integration of planar auxetic metamaterials with Helmholtz resonators.