Nonlinear Elastic Waves in Passive and Active Periodic Media

无源和有源周期性介质中的非线性弹性波

• 批准号: RGPIN-2020-06814
• 负责人: Yousefzadeh, Behrooz
• 金额: $ 1.97万
• 依托单位: Concordia University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=718016
• 关键词: Nonlinear; Elastic; Waves; Passive; Active

Nonlinear Elastic Waves in Passive and Active Periodic Media The conventional wisdom in structural dynamics is to keep the amplitudes of motion as low as possible to avoid the possibility of triggering nonlinear behavior. As a result, mechanical devices and materials are predominantly designed “around” nonlinearity. This conservative linear design perspective has a limited reach when one attempts to push the envelope of engineering design into more ambitious technologies. This is due to the fact that the linear dynamic response regime exhibits rigid and unfavorable performance characteristics such as narrow bandwidth, inability to react to changes in the operating conditions, and incorrect failure (instability) prediction. The overarching perspective of the proposed research program is to embrace the intentional utilization of nonlinearity in order to develop novel mechanical devices and materials that exhibit unprecedented wave propagation characteristics. We take advantage of periodic elastic media for this purpose: lattice materials and mechanical metamaterials are structured materials made from periodic repetitions of a basic building block. The multi-scale periodic structure of these materials provides a naturally amenable framework for implementation of nonlinearity: carefully crafted nonlinear components can lead to controlled global changes in the dynamic behavior of the material such as tunable dynamic response, localization of vibration energy, unidirectional wave propagation and asynchronous motion. These phenomena hold the key to the discovery of new materials and structured systems with unique functionalities. The proposed five-year program is focused on two main nonlinear phenomena: (i) breakdown of reciprocity, (ii) emergence of asynchronous motion. The breakdown of reciprocity enforces elastic waves to travel differently in opposite directions along the same transmission path (unidirectional propagation). This property will guide the development of advanced innovations in shielding devices and absorbing layers for shock and vibration mitigation. Asynchronous motion is a nonlinear behavior in which different components of a material oscillate at different frequencies. This type of motion will be exploited for efficient harvesting of mechanical energy from broadband sources. The proposed program will establish, theoretically and experimentally, the unrealized transformative potential of nonlinear wave propagation technologies in creation of novel lattice materials and mechanical metamaterials with highly adaptive response and selective wave control capabilities. This program contributes to the training of Canada's future technical experts in academia and industry in the field of nonlinear vibrations and wave propagation. The knowledge generated at various stages of this program enables pioneering technological innovations in several industries, with key impact in aerospace, automotive and advanced materials technologies.

被动和主动周期介质中的非线性弹性波 结构动力学的传统观点是保持运动的振幅尽可能低，以避免触发非线性行为的可能性。因此，机械设备和材料主要是围绕非线性设计的。当人们试图将工程设计的信封推向更雄心勃勃的技术时，这种保守的线性设计观点的范围有限。这是由于线性动态响应状态表现出刚性和不利的性能特征，例如窄带宽、不能对操作条件的变化做出反应以及不正确的故障（不稳定性）预测。 拟议的研究计划的总体观点是拥抱非线性的故意利用，以开发新的机械设备和材料，表现出前所未有的波传播特性。为此，我们利用周期性弹性介质：晶格材料和机械超材料是由基本构建块的周期性重复制成的结构材料。这些材料的多尺度周期性结构为实现非线性提供了一个自然可行的框架：精心制作的非线性组件可以导致材料动态行为的受控全局变化，例如可调动态响应，振动能量的局部化，单向波传播和异步运动。这些现象是发现新材料和具有独特功能的结构系统的关键。 拟议的五年计划集中在两个主要的非线性现象：（i）崩溃的互易性，（ii）出现异步运动。互易性的破坏迫使弹性波沿着沿着相同的传输路径在相反的方向上以不同的方式传播（单向传播）。这一特性将指导屏蔽装置和减震层的先进创新的发展。异步运动是一种非线性行为，其中材料的不同成分以不同的频率振荡。这种类型的运动将被用于从宽带源有效地收获机械能。 该计划将在理论和实验上建立非线性波传播技术在创造具有高度自适应响应和选择性波控制能力的新型晶格材料和机械超材料方面的未实现的变革潜力。该计划有助于在非线性振动和波传播领域的学术界和工业界培养加拿大未来的技术专家。在该计划的各个阶段产生的知识，使开拓性的技术创新在几个行业，在航空航天，汽车和先进材料技术的关键影响。