基於平面拉張超穎材料結合亥姆霍茲共振元實現共振頻率調控與伺服器風扇噪音衰減

Abstract

伺服器做為計算機系統的核心組件，隨著運算能力的提升，同時也帶來可觀的散熱需求。然而，散熱風扇在高轉速下所產生的噪音對於硬碟讀取輸出的效能產生影響。為了解決伺服器散熱風扇噪音問題，本研究提出基於平面拉張超穎材料 (planar auxetic metamaterial，PAM) 結合亥姆霍茲共振元 (Helmholtz resonator，HR) 的小型被動式通風聲學超穎材料。此結構能夠在狹小空間內實現風扇噪音的有效衰減，並透過施加結構應變改變共振元間的耦合效應，實現共振頻率的實時調控，以針對不同風扇噪音頻段進行降噪。本研究利用理論方法預測共振元耦合後的共振頻率，並與數值模擬結果進行比較，從而降低計算成本。後續利用3D列印技術以軟彈性材料製作結構，透過自製聲學裝置驗證了結構的降噪能力，並確認對結構施加不同應變能夠有效調控共振頻率，共振頻率可調範圍達到200Hz以上，調控頻率範圍與理論方法及數值模擬預測結果吻合。最後將結構安裝於伺服器內部後，驗證其能夠衰減伺服器風扇的噪音，並提升伺服器硬碟讀取輸出的效能20%以上。此研究展示了超穎材料在伺服器降噪領域的應用潛力，為高效能伺服器系統的開發提供了一種新穎且實用的解決方案。

As the core component of computer systems, servers require significant cooling capacity due to the increasing computational power they provide. However, the noise generated by high-speed cooling fans negatively impacts the performance of hard disk drives (HDDs). To address the issue of noise from server cooling fans, this study proposes a small passive ventilated acoustic metamaterial based on planar auxetic metamaterial (PAM) combined with Helmholtz resonators (HR). This structure effectively attenuates fan noise in confined spaces and allows real-time tuning of the resonance frequency by altering the coupling effect between resonators through applied strain, targeting different fan noise frequency bands. The study utilizes theoretical methods to predict the resonance frequency of coupled resonators and compares the results with numerical simulations to reduce computational costs. The structure was fabricated using 3D printing technology with soft elastic materials, and its noise reduction capability was verified using a custom-built acoustic device. It was confirmed that applying different strains to the structure can effectively tune the resonance frequency, with an adjustable range exceeding 200 Hz, matching the predictions from theoretical methods and numerical simulations. Finally, when the structure was installed inside a server, it was verified that it could reduce fan noise and improve HDD performance by more than 20%. This research demonstrates the application potential of metamaterials in server noise reduction, offering a novel and practical solution for developing high-performance server systems.