Collaborative Research: Can Irregular Structural Patterns Beat Perfect Lattices? Biomimicry for Optimal Acoustic Absorption

这项拨款支持新型建筑材料系统的发展，该系统利用不规则的几何图案来产生对声波吸收、阻抗和频率带宽的无与伦比的控制。从向日葵中发现的斐波那契图案中获得灵感，本研究将为不规则几何图案建立新的设计原则，从而彻底改变当前的几何格子设计。声学建筑材料的不规则设计提供了两个突破性的成就，目前无法通过常规设计实现：增强对非线性波动动力学的控制和扩大衰减带宽。这项研究将加深目前对人工工程和建筑材料中几何变化和集体波动动力学之间关系的物理基础的理解，并将促进下一代图案材料的发展，用于声学，电磁和光子源或探测器的各种工程应用。修补性学习发展活动将针对社会经济不利、受噪音影响社区的学校，以证明价格合理的不规则模式超材料在减轻最近飞机和机场噪音激增方面的功效，这些噪音对这些社区产生了不利影响。除了课堂活动之外，该项目还旨在通过与社区活动家的合作，使这些社区能够创造自己的适应性和经济上可行的替代品，以替代目前通常有毒的吸声产品。这个NSF项目将开发模型和实验原型，以建立几何变体在工程不规则图案材料系统中的物理定律和实际应用。这些模型基于连续统近似来预测自然界中常见的几何变化对共振晶格中声波动力学的影响。不规则的图案将以谐振器的刚度和接近度的几何变化为特征。利用该模型，我们将优化吸收、阻抗和相位特性，同时扩大不规则晶格内的频率范围，这些特性是上述几何变量的函数。基于从模型中获得的见解，声学衰减将通过原型设计执行。每个面板将结合亥姆霍兹谐振器，具有规则和不规则的斐波那契模式。主要目标是减轻200-2000赫兹频率范围内的声音，这些声音已知对人类听力和健康有害，例如来自高速公路交通、飞机、火车、机场和建筑活动的噪音。演示原型将采用室内和室外声学衰减板的形式，设计用于集成到建筑物中。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This grant supports the advancement of novel architected material systems that exploit irregular geometric patterns to produce unparalleled control over acoustic wave absorption, impedance, and frequency bandwidth. Taking inspiration from the Fibonacci pattern found in sunflowers, this research will establish new design principles for irregular geometric patterns, thus revolutionizing current geometric designs in lattices. Irregular designs of acoustic architected materials offer two groundbreaking achievements, currently unattainable through regular designs: enhanced control of nonlinear wave dynamics and expanded attenuation bandwidth. This research will deepen the current understanding of the physics underlying the relationships between geometric variations and collective wave dynamics in artificially engineered and architected materials,and will catalyze the development of the next generation of patterned materials for diverse engineering applications involving acoustic, electromagnetic, and photonic sources or detectors. Reparative learning development activities will target schools in socioeconomically disadvantaged, noise-impacted communities to demonstrate the efficacy of affordable irregular pattern metamaterials in mitigating the recent surge in noise from aircraft jets and airports that adversely affects these communities. Beyond classroom activities, the project aims, through collaboration with community activists, at empowering and enabling these communities to create their own adaptable and economically viable alternatives to current, often toxic, acoustic absorption products. This NSF project will develop models and experimental prototypes that establish the physical laws behind, and practical applications of, geometric variants in engineering irregular patterned material systems. The models are based on a continuum approximation to forecast the impact of commonly occurring geometric variations found in nature on the dynamics of acoustic waves in resonant lattices. Irregular patterns will be characterized by geometric variants of the resonators’ rigidity and proximity. Utilizing this model, we will optimize absorption, impedance, and phase properties while expanding the frequency range within irregular lattices, with these properties being functions of the mentioned geometric variants. Building on the insights gained from the models, acoustic attenuation will be executed through prototype designs. Each panel will incorporate Helmholtz resonators featuring both regular and irregular Fibonacci patterns. The primary objective is to mitigate sound in the 200-2000 Hz frequency range, known to be detrimental to human hearing and health, such as noise from highway traffic, aircraft jets, trains, airports, and construction activities. The demonstration prototypes will take the form of indoor and outdoor acoustic attenuation panels designed for integration into buildings.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.