Vibroacoustic analysis of auxetic stepped bars

There is a high demand for materials with lightweight and good acoustic properties. The noise radiated from structures has been a menace. Recently, the idea has emerged that auxetic materials provide benefits in noise insulation. In this study, a Finite Elements Method(FEM) approach is employed in this study to minimize the structure-borne radiated noise by considering two types of auxetic materials. Limited studies have been carried out on a varying thickness auxetic bar. A re-entrant and anti-tetrachiral stepped bar structure with in-plane and out-of-plane loading are considered to reduce the structure-borne noise generated from the random excitation on the bars. An enclosure as an acoustic media has been employed to avoid having a dispersed acoustic media analysis. The harmonic and acoustic analysis are performed over a frequency range of 0 – 1200 Hz. While maintaining the same mass for the re-entrant structure, there is a significant RSPL decrease of 21.4% and 10.75% in the in-plane and out-of-plane loading, respectively, as the cell angle are varied. For the anti-tetrachiral lattice, there is a significant decrease of 6.93% and 40.31% in the RSPL for the in-plane and out-of-plane orientation, respectively, as the cell radius are varied. This study proves that the out-of-plane orientation performs better in reducing the radiated sound compared to the in-plane orientation