Enhanced absorption in structural acoustic silencers using piezo-shunting.

Area of Science:

• Acoustics
• Materials Science
• Mechanical Engineering

Background:

• Structural acoustic silencers (SAS) reduce noise in ducts via reflection and absorption.
• Absorption-based transmission loss (TL) is preferred over reflection-based TL to minimize back-pressure.
• Increasing plate damping is key to enhancing absorption in SAS.

Purpose of the Study:

• To investigate the enhancement of absorption-based TL in SAS using piezo-shunting.
• To analyze the impact of piezo-shunting on the damping of flexible plates in acoustic silencers.
• To model and understand the relationship between piezo-shunting, plate impedance, and power absorption.

Main Methods:

• Experiments were conducted on a custom-made SAS using copper plates of varying thicknesses.
• Piezo-shunting was implemented by connecting an electrical resistor to a piezoelectric bimorph attached to the copper plate.
• A model was used to analyze the effect of piezo-shunting on the TL and power fractions.

Main Results:

• Piezo-shunting significantly increased the effective damping of the copper plates.
• The fraction of absorbed acoustic power was increased, while the reflected power fraction decreased.
• The study analyzed the influence of the electrical resistor value and plate impedance on these fractions.

Conclusions:

• Piezo-shunting is an effective method for improving absorption-based TL in structural acoustic silencers.
• This technique offers a way to enhance sound absorption without increasing undesirable back-pressure.
• The findings demonstrate a practical approach to optimize SAS performance through enhanced material damping.