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2 Vibrations in Physical Systems

2 2020

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Modeling of sound power transmission within duct systems

Strek Tomasz

Vibrations in Physical Systems

2020

Vol. 31, nr 3

art. no. 2020320

External boundaries of acoustic devices can channel sound propagation, and in some cases can create buildup or attenuation of acoustic energy within a confined space. In this paper, it is proposed an efficient practical numerical method (based on FEM) of calculation of attenuation of sound power transmission through ducts. The method shows its viability by presenting the reasonably consistent anticipation of the experimental result. One can observe the mechanical behaviour of the duct’s medium for lower frequencies (high transmission loss) and wave behaviour for higher frequencies (small or zero attenuation). The authors proved that mechanical vibrations of medium reduce the possibility of acoustic energy transmission in duct systems. The radiation impedance for the duct is calculated as well.

Blast resistance of sandwich plate with auxetic anti-tetrachiral core

Michalski Jakub, Strek Tomasz

Vibrations in Physical Systems

2020

Vol. 31, nr 3

art. no. 2020317

Auxetic structures exhibit unusual behavior not only when subjected to static loads but also in case of dynamic events. However, their response to transient loads still requires further research. In this article, the blast resistance of auxetic and non-auxetic sandwich plates was compared using the finite element method. The first stage of works, that consisted of the analyses of plates with homogenized core with different values of Poisson’s ratio subjected to blast load, proved that auxetic core may increase the resistance to this kind of load. In the next step, two sandwich plates were compared - one with auxetic anti-tetrachiral core and one with a non-auxetic hexagonal honeycomb core. Obtained results indicate that auxetic plate has superior blast resistance when compared with the regular sandwich panel.