Negative-Viscosity Materials: Exploiting the Effect of Negative Mass

Materials, Journal Year: 2025, Volume and Issue: 18(6), P. 1199 - 1199

Published: March 7, 2025

The research is motivated by the search for materials with negative viscosity to exploit effect of mass. We introduce media (gaseous and liquid) that demonstrate viscosity. Consider vibrated plate, which vertically pulled through ideal gas built from core–shell “meta-molecules”. Vibrating vertical plate supplies an excess momentum meta-molecules. If frequency vibrations larger than resonant frequency, moment oriented against direction motion; thus, becomes possible. effective when approaches above. Thus, a novel physical mechanism resulting in introduced. No violation energy conservation observed; supplied system external source vibrating plate. also possible liquids. Frequency dependence addressed. Asymptotic expressions are derived frequency-dependent Introduced meta-materials may be exploited development prescribed rheological properties. Possible realizations negative-viscosity discussed.

Language: Английский

Negative Refraction Guided by a Glide-Reflection Symmetric Crystal Interface

Materials, Journal Year: 2025, Volume and Issue: 18(6), P. 1210 - 1210

Published: March 8, 2025

Research on phononic crystals with negative refractive indices constitutes the most crucial approach to achieving ultra-high-resolution acoustic lenses. This study presents a glide-reflection (GR) symmetrical crystal (PC), and mismatch of Wannier center between two PCs leads emergence edge states (ESs). By constructing single-domain wall, refraction is achieved due excitation ESs dispersion. Further, by stacking multiple GR symmetric PC interfaces, coupled (CESs) are found, which originate from coupling adjacent interfaces. Thus, stronger sound effects transverse displacement can be achieved, because incident wave into CESs Simulation results conducted using finite element method verify our idea, research provides novel methodology for design refraction.

Language: Английский

A novel theoretical and computational framework to quantify dielectric relaxation effects on lamb waves in piezocomposites

International Journal of Engineering Science, Journal Year: 2025, Volume and Issue: 211, P. 104260 - 104260

Published: March 27, 2025

Language: Английский