تحلیل فرکانسی فراماده آکوستیکی بر مبنای تشدیدگر هلمهولتز کوپل‌شده با غشا به منظور کاهش نویز در جاروبرقی

In this research, a double Helmholtz resonator structure coupled with a membrane is considered, and frequency analysis is performed to find the peaks in its Sound Transmission Loss (STL) plot. The method of shifting these natural frequencies to the target frequency range is investigated. Subsequently, optimization is required to increase the Sound Transmission Loss (STL) value within the target frequency range. Simulations are carried out in COMSOL software.

Considering the complexity of the structure, first, a simplified model consisting of a pipe with a membrane-coupled Helmholtz resonator placed in the middle is analyzed, and a frequency analysis is performed for it. In this section, the frequency range of 0 to 2000 Hz is considered. Next, a single layer of the proposed structure, which has membranes on both sides, is considered, and the process from the previous step is repeated for this structure up to a frequency of 2600 Hz. The results of the frequency analysis for both steps are identical.

As can be seen from the natural frequency relationship of the Helmholtz resonator, the cavity volume is one of the influential parameters on this frequency. The findings of this research showed that the natural frequency of the Helmholtz resonator still follows the Helmholtz volume after coupling with the membrane. In other words, when the membrane mode shape is such that it changes the Helmholtz cavity volume, a peak appears in the STL plot at this mode.

In the simple model analysis, it was observed that all three modes in which the Helmholtz resonator cavity volume changes create a peak in the STL plot. Furthermore, using frequency analysis incurs lower computational costs compared to analysis over the entire frequency range. The experimental investigation of the sound absorption performance of this metamaterial belongs to future steps and will be conducted later.