Mojahed Alireza, Gendelman Oleg V, Vakakis Alexander F
Mechanical Science and Engineering, University of Illinois, Urbana, Illinois 61801, USA.
Faculty of Mechanical Engineering, Technion, Haifa, Israel.
J Acoust Soc Am. 2019 Jul;146(1):826. doi: 10.1121/1.5114915.
The effect of on-site damping on breather arrest, localization, and non-reciprocity in strongly nonlinear lattices is analytically and numerically studied. Breathers are localized oscillatory wavepackets formed by nonlinearity and dispersion. Breather arrest refers to breather disintegration over a finite "penetration depth" in a dissipative lattice. First, a simplified system of two nonlinearly coupled oscillators under impulsive excitation is considered. The exact relation between the number of beats (energy exchanges between oscillators), the excitation magnitude, and the on-site damping is derived. Then, these analytical results are correlated to those of the semi-infinite extension of the simplified system, where breather penetration depth is governed by a similar law to that of the finite beats in the simplified system. Finally, motivated by the experimental results of Bunyan, Moore, Mojahed, Fronk, Leamy, Tawfick, and Vakakis [Phys. Rev. E 97, 052211 (2018)], breather arrest, localization, and acoustic non-reciprocity in a non-symmetric, dissipative, strongly nonlinear lattice are studied. The lattice consists of repetitive cells of linearly grounded large-scale particles nonlinearly coupled to small-scale ones, and linear intra-cell coupling. Non-reciprocity in this lattice yields either energy localization or breather arrest depending on the position of excitation. The nonlinear acoustics governing non-reciprocity, and the surprising effects of existence of linear components in the coupling nonlinear stiffnesses, in the acoustics, are investigated.
研究了现场阻尼对强非线性晶格中呼吸子捕获、局域化和非互易性的影响,采用了解析和数值方法。呼吸子是由非线性和色散形成的局域振荡波包。呼吸子捕获是指呼吸子在耗散晶格中有限的“穿透深度”内解体。首先,考虑了一个在脉冲激励下两个非线性耦合振子的简化系统。推导了拍频数(振子间的能量交换)、激励幅度和现场阻尼之间的精确关系。然后,将这些解析结果与简化系统半无限扩展的结果相关联,其中呼吸子穿透深度由与简化系统中有限拍频类似的规律控制。最后,受Bunyan、Moore、Mojahed、Fronk、Leamy、Tawfick和Vakakis [《物理评论E》97, 052211 (2018)] 的实验结果启发,研究了非对称、耗散、强非线性晶格中的呼吸子捕获、局域化和声非互易性。该晶格由线性接地的大规模粒子与小规模粒子非线性耦合的重复单元以及单元内线性耦合组成。根据激励位置,该晶格中的非互易性会导致能量局域化或呼吸子捕获。研究了控制非互易性的非线性声学,以及耦合非线性刚度中线性分量的存在在声学中产生的惊人效果。