Material with Tunable Constitution for Elastodynamic Deformation

结构复合材料是由两种或两种以上具有不同性能的组成材料组成的材料，当它们组合在一起时，会显示出独特的力学性能。可以选择和排列单个组件以获得所需的性能，如高刚性和低密度。然而，在传统的复合材料中，这些性质是恒定的，如果不永久性地改变材料的结构或组成，就不能改变。该奖项支持基础研究，以便能够分析和设计一种可按需和即时调整的新型复合材料。这些可调材料将以内部流动通道网络为特色，允许主动调节密度、弹性常数和阻尼性。这种可调复合材料能够在广泛的应用中实现振动和声学控制的全新策略。这项研究结合了多个学科，包括弹性动力学、本构模型、动态均化、流固耦合、能带结构计算和设计优化。研究的多学科性质将为参与这一项目的学生提供一个激励的环境，并扩大未被充分代表的群体在研究中的参与。推广活动将吸引K-12年级的学生设计具有可调特性的工程材料，以及与波动和材料力学有关的基本概念。本项目的具体目标是为可调复合材料建立严格的动态均化理论。该理论将考虑耗散对复合材料性能的影响。这一理论将被用于分析和设计由周期性的谐振器阵列和内置的流动通道网络组成的流体超材料，这些流动通道具有不同的流体组成和流动条件。将建立一种拓扑优化方案，以最大限度地提高新兴流体结构材料系统的实时性能。建立在简谐波传播的Bloch理论的基础上，动态均匀化的研究将建立一种获得密度张量、阻尼张量和弹性张量的频率相关有效性质的方法。建立了一个基于有限元时域格式的计算框架，用于计算流固耦合系统的能带结构。将探索一种梯度驱动的拓扑优化方法，使用水平集和扩展有限元方法来优化布置流体和固体相。由此产生的可调超材料代表着向多功能复合材料的重大转变，这种复合材料本质上是动态的、自适应的和吸收能量的，为声音和振动控制提供了前所未有的新机会。

Structural composites are materials consisting of two or more constituent materials with different properties, that when combined, exhibit unique mechanical properties. The individual constituents can be chosen and arranged to achieve desirable properties, such as high stiffness and low density. In a conventional composite, however, these properties are constant and cannot be changed without permanently changing the structure or composition of the material. This award supports fundamental research to enable the analysis and design of a new class of composite materials that are tunable on-demand and on-the-fly. These tunable materials will feature internal networks of flow channels that allow active tuning of the density, elastic constants, and damping properties. The tunable composites enable fundamentally new strategies for the control of vibration and acoustics across a wide range of applications. This research combines several disciplines including elastodynamics, constitutive modeling, dynamic homogenization, fluid-structure interaction, band structure calculations, and design optimization. The multi-disciplinary nature of the research will provide a stimulating setting for students who will participate in this project and broaden participation of underrepresented groups in research. Outreach activities will attract K-12 students to the design of engineered materials with tunable properties and the underlying concepts pertaining to wave motion and mechanics of materials.The specific objectives of this project are to establish a rigorous dynamic homogenization theory for the tunable composites. The theory will account for the effects of dissipation on the composite properties. This theory will be used towards the analysis and design of fluidic metamaterials consisting of periodic arrays of resonators intertwined with a built-in network of flow channels with varying fluid composition and flow conditions. A topology optimization scheme will be established to maximize the real-time performance of the emerging fluid-structure material system. Building upon Bloch theory for harmonic wave propagation, the research on dynamic homogenization will establish a methodology for obtaining frequency-dependent effective properties for the density, damping, and elasticity tensors. A computational framework based on a finite-element time-domain scheme will be created for computing the band structure of the coupled fluid-structure system. A gradient-driven topology optimization methodology using level sets and the extended finite element method will be explored to optimally arrange fluid and solid phases. The resulting tunable metamaterial represents a major transformation to what constitutes a multi-functional composite that is intrinsically dynamic, adaptive, and energy absorbing, providing unprecedented new opportunities for sound and vibration control.