On negative effective mass and negative group velocity in anharmonic seismic metamaterials

IF 1.5 Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY
R. Zivieri
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引用次数: 1

Abstract

In this work, an anharmonic mass-in-mass system that can be employed as a nonlinear seismic metamaterial is represented as an equivalent anharmonic mass-spring system via an effective medium approach. The dispersion relation and the behavior of the effective mass as a function of the angular frequency obtained in the regime of weak anharmonicity deviate from those of the corresponding linear system because of the effect of the fourth-order potential anharmonicity. In the presence of anharmonic soft springs it is found a range of wave vectors close to the Brillouin border zone at which the group velocity of the acoustic and optical modes is negative, namely it is opposite to the phase velocity, and a wider band gap at the border of the first Brillouin zone with respect to that of the linear case. Both effects can be tuned by varying the anharmonicity strength. The huge band gap amplitude together with the strong reduction of the frequency of the acoustic mode could be exploited for the design of nonlinear seismic metamaterials at the basis of composite foundations operating in the stop band frequencies.
非调和地震超材料的负有效质量和负群速度
在这项工作中,可以作为非线性地震超材料的非调和质量-质量系统通过有效介质方法被表示为等效的非调和质量-弹簧系统。由于四阶势非谐性的影响,在弱非谐性条件下得到的色散关系和有效质量随角频率的变化规律偏离了相应的线性系统。在非调和软弹簧存在的情况下,发现在布里渊边界区附近有一个波矢量范围,在该范围内声光模式的群速度为负,即与相速度相反,并且在第一布里渊区边界处的带隙比线性情况下的带隙更宽。这两种效应都可以通过改变非谐波强度来调节。巨大的带隙幅值和声模态频率的强烈降低,可用于复合地基的非线性地震超材料的设计。
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来源期刊
EPJ Applied Metamaterials
EPJ Applied Metamaterials MATERIALS SCIENCE, MULTIDISCIPLINARY-
CiteScore
3.10
自引率
6.20%
发文量
16
审稿时长
8 weeks
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