Research on Semi-passive Shunted Piezoelectric Layer for Sound Absorption with FEM

Semi-passive shunted piezoelectric layer for sound absorption is a typically multi-physics problem coupled with sound wave equations, structure stress-strain equations, piezoelectric constitutive equations and electric ordinary equations, and it is analyzed with FEM in detail. Frequency response characteristics are simulated when semi-passive piezoelectric sound absorption structure shunted with negative-capacitance, resistance and negative-inductance in series. Reflection loss, transmission loss and sound absorption spectra are obtained at low and mid frequencies. When shunted with proper electrical elements and used ideal lossless material, wonderful sound absorption spectra at low and mid frequencies can be obtained. But the loss of material deteriorates the sound absorption ability intensively. Negative capacitance has an important influence on the performance, and it is the sensitive parameter. The values of inductance are also very important because it provides matching conditions of piezoelectric material and water especially at high frequencies. Damping is controlled by resistance at the whole band. The thickness of piezoelectric material has to be properly selected since sound absorption band is moved to low frequencies when the thickness increasing. Due to its ordinary electrical parameters, the sound absorption system is realizable in practice.