  This paper analyzes the possibility of increasing the acoustic transmission
loss of sound transmitted through planar or curved glass shells using attached
piezoelectric macro fiber composite (MFC) actuators shunted by active circuits
with a negative capacitance. The key features that control the sound
transmission through the curved glass shells are analyzed using an analytical
approximative model. A detailed analysis of the particular arrangement of MFC
actuators on the glass shell is performed using a finite element method (FEM)
model. The FEM model takes into account the effect of a flexible frame that
clamps the glass shell at its edges. A method is presented for the active
control of the Young's modulus and the bending stiffness coefficient of the
composite sandwich structure that consists of a glass plate and the attached
piezoelectric MFC actuator. The predictions of the acoustic transmission loss
frequency dependencies obtained by the FEM model are compared with experimental
data. The results indicate that it is possible to increase the acoustic
transmission loss by 20 and 25 dB at the frequencies of the first and second
resonant modes of the planar and curved glass shells, respectively, using the
effect of the shunt circuit with a negative capacitance.
