Abstract
Phononic materials structured at the macro- or nano-scale are at the forefront of materials research for controlling transport of sound and heat, respectively. Besides the structure length scale, the exact geometry has been found to be of relevance as well. In this work, we provide an extensive finite element investigation of the effect of the shape of periodically dispersed inclusions in a 2D matrix on propagation and attenuation of an acoustic wave packet. We show that, by significantly complexifying the shape from circular to fractal-like (dendrite shape), phonon scattering at wavelengths comparable with the inner structure of the inclusion is enhanced, leading to a strong attenuation that can be fitted by a compressed exponential function, while in the circular case, the diffusive regime is observed.
Highlights
Heterogeneous architectured materials are of particular interest in engineering applications.1 These are man-made structural materials that have been developed for obtaining ad hoc properties, which cannot be generally found in nature
Ω/ω0 > 1.2, and no gaps are present in the propagation direction, indicating that if propagation is mainly affected by the modification of the band structure at low frequency, in this range, the dominant effect is the multiple scattering from the fine interface structure of the dendrite
We have shown the effect of a complex shape in the periodic pattern of a 2D nanophononic crystal
Summary
Heterogeneous architectured materials are of particular interest in engineering applications. These are man-made structural materials that have been developed for obtaining ad hoc properties, which cannot be generally found in nature. Recent works have looked at the phonon dynamics to get a better insight into transport properties and found exotic behaviors such as an energy localization between pores, asymmetric transport (rectification), or the filtering of high-frequency phonons.33 It is, clear that, depending on the length scale at play, the design of the phononic crystal structure contributes directly to the performance of filtering, hindering, and guiding the propagation of acoustic waves (phonons), responsible for the sound propagation when their wavelength is macroscopic and for the thermal transport at room temperature when their wavelength is nanometric.. To have a deep understanding of the role of the dendritic shape inclusion in acoustic attenuation and dynamic properties of the phononic crystal, we have performed finite element simulations of out-of-equilibrium acoustic wave-packet propagation in 2D nanocomposite periodically distributed circular and dendritic inclusions This has allowed us to establish a direct comparison between simple and complex geometries. IV, we compare the acoustic attenuation properties in two media containing softer or stiffer inclusions with dendritic and circular shapes; we discuss the results, and we conclude in the last part
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
