Noise suppression in curved glass shells using macro-fiber-composite actuators studied by the means of digital holography and acoustic measurements

Abstract

The paper presents methods and experimental results of the semi-active control of noise transmission in a curved glass shell with attached piezoelectric macro fiber composite (MFC) actuators. The semi-active noise control is achieved via active elasticity control of piezoelectric actuators by connecting them to an active electric shunt circuit that has a negative effective capacitance. Using this approach, it is possible to suppress the vibration of the glass shell in the normal direction with respect to its surface and to increase the acoustic transmission loss of the piezoelectric MFC-glass composite structure. The effect of the MFC actuators connected to the negative capacitance shunt circuit on the surface distribution of the normal vibration amplitude is studied using frequency-shifted digital holography (FSDH). The principle of the used FSDH method is described in the paper. The frequency dependence of the acoustic transmission loss through the piezoelectric MFC-glass composite structure is estimated using measurements of the specific acoustic impedance of the curved glass shell. The specific acoustic impedance is measured using two microphones and a laser Doppler vibrometer (LDV). The results from the LDV measurements are compared with the FSDH data. The results of the experiments show that using this approach, the acoustic transmission loss in a glass shell can be increased by 36 dB in the frequency range around 247 Hz and by 25 dB in the frequency range around 258 Hz. The experiments indicate that FSDH measurements provide an efficient tool that can be used for fast and accurate measurements of the acoustic transmission loss in large planar structures.

Adaptive acoustic metasurfaces for the active sound field control

“…The analysis of the functionality of the proposed noise shielding device was presented in [12] and the detailed numerical model of all material parameters of used MFC actuators was performed in [16]. The noise shielding device has been successfully fabricated and its function has been tested by means of the measurements of frequency dependence of SAI [9]. The pressure difference at the opposite sides of the AAMS has been measured using two microphones.…”

100 years of piezoelectric materials in acoustics: From a sonar to active metasurfaces

“…large planar structures with the negative acoustic impedance. 14 Independently, several groups around the world have constructed active acoustic metamaterials and metasurfaces which employ the piezoelectric materials.…”