Effects of Shapes of Deployable Cylinders on Acoustic Properties of Resonators

Abstract

In this study, origami-based deployable cylinders are used to change the neck length of Helmholtz resonator. The cylinder is constructed by folding a pattern with regularly aligned parallelograms and joining the side edges of the pattern together. Acoustic modal analysis using the finite element method was performed on four resonators with different design variable β. The resonance frequency of the resonator with small β monotonously increased by shortening length of the neck. While, the resonant frequencies of the resonators with large β decreased and then increased by the change in the neck lengths. It was revealed that small β was appropriate for providing a unique neck length to achieve a target resonance frequency. Under the given conditions of this study, the variable β must be 35°or less. To investigate the noise reduction effect, the frequency response of sound pressure level was measured on a simple acoustic tube without and with the resonator changing the neck length. The proposed resonator mitigated a sound pressure peak and showed the same acoustic properties as the conventional Helmholtz resonator. Furthermore, it possibly functions effectively at different target frequencies by adjusting the neck length.