应校内著名学者项目和现代设计及转子轴承系统教育部重点实验室曹军义教授邀请，佐治亚理工学院 ASME Fellow, Alper Erturk 副教授来我院做学术讲座，欢迎各位感兴趣的同学和老师参加。

报告题目：Enhanced elastic wave energy harvesting concepts leveraging phononic crystals

报告时间：2018年8月15日（星期三）上午10:00-11:00

报告地点：科技园西五楼第一会议室A420

Abstract: This talk will review our recent efforts on the leveraging of phononic crystals in structure-borne wave energy harvesting. The two approaches of interest for elastic wave energy focusing and harvesting are the use of lens and mirror structures. In the first lens scenario, we will discuss our computational and experimental results on the focusing and harvesting of plane waves by means of a Gradient-Index (GRIN) Phononic Crystal (PC) lens. The proposed GRIN-PC lens is formed by an array of blind holes with different diameters. The blind hole distribution is tailored to obtain a hyperbolic secant profile of refractive index for the lowest antisymmetric Lamb wave mode. The second lens concept is an omnidirectional PC Luneburg lens with hexagonal unit cells hosting blind holes, and it alleviates the directivity issue owing to its axisymmetric refractive index profile. In both of these GRIN-PC lens concepts, a piezoelectric energy harvester located at the focus yields an order of magnitude larger electrical power as compared to the baseline case of harvesting on the flat plate. Another GRIN-PC lens configuration we will discuss is a 3D-printed lens domain of nylon stubs with different heights to achieve the required refractive index profile. We will also review our structurally-embedded mirror (SEM) concepts for the reflective focusing and energy harvesting in a flat aluminum plate hosting blind holes with metallic (e.g. tungsten) inclusions. The relationship between SEM geometry and wavelength is unveiled in order to minimize the energy in the side lobes near the focus. The frequency dependence of the reflection coefficient of embedded spherical inclusions is also investigated to understand the limitations of the approach due to transmission resonances of the inclusions. Dramatic enhancement of the harvested power (by an order of magnitude) is validated experimentally using an elliptical SEM made from spherical tungsten inclusions in an aluminum plate. Finally, low-frequency lens and mirror concepts using locally resonant unit cells will be discussed.

学者简介：Alper Erturk博士是佐治亚理工学院机械工程学院副教授，伍德拉夫学院Fellow和ASME的Fellow。他的研究领域包括能量俘获、仿生驱动、超材料和无线声功率传输，共发表约200篇论文，2本专著，总引用次数超过9700，h-index: 45。Erturk博士获得2013年美国国家科学基金会的“杰出青年教授奖”，2015年的ASME Gary Anderson早期成就奖，2017年ASME C.D. Mote Jr.早期成就奖以及2015年和2017年ASME能量俘获领域最佳论文奖。目前他是Smart Materials & Structures (IOP), Journal of Intelligent Material Systems & Structures (SAGE)和Journal of Vibration & Acoustics (ASME)等期刊的副主编，也是ASME能量俘获技术委员会的Founding Chair，2018 ASME IDETC Mechanical Vibration & Noise Conference和2018 SPIE Smart Structures/NDE - Active & Passive Smart Structures & Integrated Systems Conference的会议主席。