###### Abstract
Layered metamaterials find unique potential in situations where more unit cells are needed and elongation of the single beam is impracticable. The application of layered metamaterial beams in dual-purpose vibration isolation energy harvesting using piezoelectricity was demonstrated by [PERSON] et al. [21]. In their work, layered metamaterial beams were designed and piezoelectric materials were placed on each local resonator for conversion of localized vibrations into electric power. Their results showed that electric energy could be aggregated from conversion of vibrations trapped in multiple local resonators in all layers of the metamaterial beams. Additionally, [PERSON] et al. reported a 3D printed layered metamaterial beam for synchronous vibration attenuation energy harvesting using magnetomotive effect [14]. Coils were placed on the tips of all local resonators and used to convert the vibrations from the local resonators into useful electric power around the resonant frequencies of these resonators. The key interest of the current work is to investigate the possible advantages offered by layered-beam metamaterial structures over typical single-beam metamaterial structures of the same kind [7; 18; 28]. Specifically, the current study investigates improvements in transmissibility bandgaps offered by layered-beam metamaterial structures in terms of lowering the frequency bandgaps, increasing the transmissibility depth, and opening multiple bandgaps. Since layered-beam metamaterial structures with local resonators are demonstrating growing engineering potential, it is important to study the advantages in bandgap generation offered by these layered metamaterial structures over typical single-beam metamaterial structures. In the application of metamaterial beam structures as dual-purpose systems for electric power generation, the more the local resonators (unit cells) per miniature device, the more the aggregate electric power generation potential of the device. This is because the electromechanical transducers are usually placed inside the local resonators. In such cases, having a layered metamaterial structure is physically an attractive choice. Because the existence of multiple bandgaps is very desirable in such structures, a major goal of the work presented in this article is performing a comparative analysis and design study between layered- and single-beam metamaterial structures. In previous work, we developed a generic model approach for layered metamaterial beam structures with local resonators [19]. The [PERSON] method and principle of superposition of mode shapes were used to resolve the peculiar Euler-Bernoulli beam equations for layered-beam metamaterial structures formulated in our previous work. Our prior work was validated experimentally using a 3D printed metamaterial prototype and further confirmed using dispersion curves [14; 19]. While our previous work was focused on establishing a design criteria and platform for modeling a layered-beam metamaterial structure, it stopped short from investigating the advantages offered by layered-beam metamaterial structures over single-beam metamaterial structures in terms of bandgaps formation and vibration transmissibility. This is the main focus of the current work. Motivated by the key and growing role that layering beams are taking in design and implementation of dual-purpose metamaterial structures, the current article is focused on studying the possible advantages in bandgap formation of these layered-beam metamaterial structures. Thus, the main objective of the work presented in this article is to creat a platform and an awareness of these advantages that can help researchers in designing metamaterial beam structures for various applications including vibration attenuation and energy harvesting. In this work, the effects of layering the metamaterial beams on their performance are analyzed and possible advantages are highlighted.