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质的组成材料组成的材料，当组合时，表现出独特的机械性能。可以选择和布置各个成分以实现期望的特性，例如高刚度和低密度。然而，在常规复合材料中，这些性质是恒定的，并且在不永久改变材料的结构或组成的情况下不能改变。该奖项支持基础研究，以分析和设计一类可按需和实时调节的新型复合材料。这些可调材料将具有内部流动通道网络，允许主动调节密度，弹性常数和阻尼特性。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。这项研究结合了几个学科，包括弹性动力学，本构建模，动力均匀化，流体-结构相互作用，带结构计算，和设计优化。研究的多学科性质将为参与该项目的学生提供一个激励环境，并扩大代表性不足的群体在研究中的参与。外展活动将吸引K-12学生设计具有可调性能的工程材料，以及与材料波动和力学相关的基本概念。该项目的具体目标是为可调复合材料建立严格的动态均匀化理论。该理论将考虑耗散对复合材料性能的影响。该理论将用于分析和设计流体超材料，其由与具有不同流体成分和流动条件的流动通道的内置网络交织的谐振器的周期性阵列组成。将建立一个拓扑优化方案，以最大限度地提高新兴的流体-结构材料系统的实时性能。基于Bloch谐波传播理论，动力均匀化研究将建立一种获得密度、阻尼和弹性张量的频率相关有效性质的方法。一个计算框架的基础上的有限元时域计划将被创建用于计算的耦合流体-结构系统的带结构。一个梯度驱动的拓扑优化方法，使用水平集和扩展的有限元方法将探索最佳安排流体和固体相。由此产生的可调超材料代表了构成多功能复合材料的重大转变，该复合材料具有内在的动态，自适应和能量吸收，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.