Acoustic Meta-materials Incorporating the KDamper Concept for Low Frequency Acoustic Isolation
Periodic structures with unit cells exhibiting local resonance known as "acoustic/elastic meta-materials", present unique wave propagation properties at wavelengths well below the regime corresponding to band-gap generation based on spatial periodicity. Therefore, they are rendered
especially suitable in low-frequency range applications. In order to overcome the main constraints encountered in such cases, including heavy internal oscillating masses with amplitude limitations, the KDamping passive, vibration isolation and damping concept is proposed as the base of the
periodic structure. According to this concept, the resulting acoustic/elastic meta-materials are designed to include negative stiffness elements instead of or in addition to the internally resonating masses. This, deals effectively with the requirement for heavy locally added masses, while
simultaneously exploits the negative stiffness damping phenomenon. Analysis of the one-dimensional mass-in-mass lattice via application of Bloch's theory and classical modal analysis is performed and the corresponding dispersion relations are derived. Furthermore, a preliminary examination
of a practical implementation is attempted via structural realization of the aforementioned negative stiffness element. Additionally, the KDamper meta-material is analysed and subjected to harmonic and broadband noise excitations. Corresponding results and comparisons between the KDamper,
"mk-m" (mass-spring-mass) and Tuned Mass Damper based periodic structures, indicate significant improvements and advantages over the conventional mass-in-mass lattice, such as broader band-gaps and increased damping ratio, revealing significant potential in low frequency acoustic isolation/damping.
Document Type: Research Article
Publication date: 01 July 2018
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