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Metamaterial-based broadband elastic wave absorber
This article presents modeling and analysis techniques for and reveals the actual working mechanism of longitudinal metamaterial bars as elastic wave absorbers. A metamaterial-based elastic wave absorber can be a uniform isotropic bar with many tiny spring-mass subsystems attached at separated longitudinal locations. In the literature, each cell that consists of a bar segment and an attached spring-mass subsystem is modeled as a discrete system of two degrees of freedom by integration and/or finite difference, and the idealized model becomes a dispersive medium for elastic waves and has a stop band that allows no waves to propagate forward. This work shows that these idealized models can be used only for elastic waves having wavelengths much longer than the unit cellgs length. Moreover, it is revealed that a metamaterial-based elastic wave absorber is actually based on the concept of conventional mechanical vibration absorbers, which uses the local resonance of subsystems to generate inertia forces to work against the external load and prevent elastic waves from propagating forward. This concept is extended to design a broadband absorber that works for elastic waves of any wavelengths, including waves having wavelengths shorter than the unit cellgs length. Numerical examples validate the design and reveal the cause of stop band. Moreover, the effect of negative effective mass and acoustic and optical modes are explained.
Metamaterial-based broadband elastic wave absorber
This article presents modeling and analysis techniques for and reveals the actual working mechanism of longitudinal metamaterial bars as elastic wave absorbers. A metamaterial-based elastic wave absorber can be a uniform isotropic bar with many tiny spring-mass subsystems attached at separated longitudinal locations. In the literature, each cell that consists of a bar segment and an attached spring-mass subsystem is modeled as a discrete system of two degrees of freedom by integration and/or finite difference, and the idealized model becomes a dispersive medium for elastic waves and has a stop band that allows no waves to propagate forward. This work shows that these idealized models can be used only for elastic waves having wavelengths much longer than the unit cellgs length. Moreover, it is revealed that a metamaterial-based elastic wave absorber is actually based on the concept of conventional mechanical vibration absorbers, which uses the local resonance of subsystems to generate inertia forces to work against the external load and prevent elastic waves from propagating forward. This concept is extended to design a broadband absorber that works for elastic waves of any wavelengths, including waves having wavelengths shorter than the unit cellgs length. Numerical examples validate the design and reveal the cause of stop band. Moreover, the effect of negative effective mass and acoustic and optical modes are explained.
Metamaterial-based broadband elastic wave absorber
Pai, P.Frank (author)
Journal of Intelligent Material Systems and Structures ; 21 ; 517-528
2010
12 Seiten, 11 Quellen
Article (Journal)
English
Akustik , akustisches Signal , breites Frequenzband , elastische Welle , Längsrichtung , mathematisches Modell , mechanische Dämpfung , mechanische Schwingung , mechanische Spannungsverteilung , mechanisches Modell , numerische Analyse , optisches Signal , Resonanzabsorption , Schwingungsdämpfer , Schwingungsdämpfung , Wellenausbreitung , Wellenlängenabhängigkeit
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