Naveed Ali Bin, Mubashar Aamir, Khan Muhammad Khizer Ali, Munir Adnan, Khan Kamran A
School of Mechanical and Manufacturing Engineering (SMME), National University of Science and Technology (NUST), Sector H-12, Islamabad, Pakistan.
Department of Aerospace Engineering, Khalifa University of Science and Technology, PO Box 127788, Abu Dhabi, UAE.
Sci Rep. 2025 Jul 2;15(1):23460. doi: 10.1038/s41598-025-06970-2.
Re-entrant auxetic designs, known for their superior mechanical properties, are increasingly explored in various industrial applications. This study aims to enhance the multifunctionality of such designs by preserving their mechanical characteristics while improving their acoustic performance. A multi-layer hybrid structure integrating microperforated panels with auxetic geometry was proposed. This design enabled each auxetic cavity to function as a Helmholtz resonator. Sample fabrication was performed with fused deposition modeling (FDM), an Additive Manufacturing technique, using PLA as build material. The perforations and minimum structural features were designed to maintain structural integrity and mechanical properties while facilitating ease of manufacturing. A computational modeling approach was verified and validated using numerical and experimental results from the literature. Impedance tube testing techniques were employed to validate the numerical model for sound transmission loss (STL) and sound absorption coefficient (SAC), ensuring precise measurement of acoustic properties and confirming the accuracy of the simulations. A total of 18 variants of proposed design were numerically examined in the low to mid-frequency range (50-1800 Hz). The effects of various geometric and material parameters on acoustic performance were recorded. Results indicate substantial enhancement in SAC as well as STL from baseline design of the same dimensions. SAC above 0.5 was achieved for a broad frequency range of 1180 Hz with an average STL of 55 dB. This research advances the development of multifunctional subwavelength metamaterials by presenting a structure that exhibits exceptional STL and SAC-a combination not previously documented in recent literature.
具有优异机械性能的折返式负泊松比设计在各种工业应用中得到了越来越多的探索。本研究旨在通过保留其机械特性同时改善其声学性能来增强此类设计的多功能性。提出了一种将微穿孔板与负泊松比几何结构相结合的多层混合结构。这种设计使每个负泊松比腔都能起到亥姆霍兹共振器的作用。使用熔融沉积建模（FDM）这一增材制造技术，以聚乳酸（PLA）作为构建材料进行样品制作。穿孔和最小结构特征的设计是为了在便于制造的同时保持结构完整性和机械性能。利用文献中的数值和实验结果对一种计算建模方法进行了验证。采用阻抗管测试技术来验证用于声传输损失（STL）和吸声系数（SAC）的数值模型，确保对声学特性进行精确测量并确认模拟的准确性。在低至中频范围（50 - 1800 Hz）内对总共18种所提出设计的变体进行了数值研究。记录了各种几何和材料参数对声学性能的影响。结果表明，与相同尺寸的基线设计相比，SAC以及STL都有显著提高。在1180 Hz的宽频率范围内实现了SAC高于0.5，平均STL为55 dB。本研究通过展示一种具有卓越STL和SAC的结构——这是近期文献中未曾记载的组合，推动了多功能亚波长超材料的发展。
