Trainiti G, Ra'di Y, Ruzzene M, Alù A
Daniel Guggenheim School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX 78712, USA.
Sci Adv. 2019 Aug 30;5(8):eaaw3255. doi: 10.1126/sciadv.aaw3255. eCollection 2019 Aug.
Absorbers suppress reflection and scattering of an incident wave by dissipating its energy into heat. As material absorption goes to zero, the energy impinging on an object is necessarily transmitted or scattered away. Specific forms of temporal modulation of the impinging signal can suppress wave scattering and transmission in the transient regime, mimicking the response of a perfect absorber without relying on material loss. This virtual absorption can store energy with large efficiency in a lossless material and then release it on demand. Here, we extend this concept to elastodynamics and experimentally show that longitudinal motion can be perfectly absorbed using a lossless elastic cavity. This energy is then released symmetrically or asymmetrically by controlling the relative phase of the impinging signals. Our work opens previously unexplored pathways for elastodynamic wave control and energy storage, which may be translated to other phononic and photonic systems of technological relevance.
吸收器通过将入射波的能量耗散为热量来抑制其反射和散射。当材料吸收趋近于零时，撞击物体的能量必然会被透射或散射掉。对入射信号进行特定形式的时间调制可以在瞬态状态下抑制波的散射和透射，在不依赖材料损耗的情况下模拟完美吸收器的响应。这种虚拟吸收可以在无损材料中高效地存储能量，然后按需释放。在此，我们将这一概念扩展到弹性动力学，并通过实验表明，使用无损弹性腔可以完美吸收纵向运动。然后，通过控制入射信号的相对相位，这些能量可以对称或不对称地释放。我们的工作为弹性动力学波控制和能量存储开辟了以前未探索的途径，这可能会推广到其他具有技术相关性的声子和光子系统。
