Dynamic Electromechanical Coupling of Piezoelectric Bending Actuators

Area of Science:

• Materials Science
• Mechanical Engineering
• Electrical Engineering

Background:

• Piezoelectric actuators are crucial for energy conversion applications.
• Understanding electromechanical coupling is key to actuator performance.
• Existing models lack explicit calculation of dynamic electromechanical coupling factor (dynamic EMCF) for various configurations.

Purpose of the Study:

• To develop explicit expressions for calculating the dynamic EMCF in cantilever piezoelectric actuators.
• To analyze the influence of layer arrangement, geometry, and material selection on dynamic EMCF.
• To provide a design framework for optimizing piezoelectric actuator performance.

Main Methods:

• Modeling piezoelectric actuators using standard constitutive dynamic equations.
• Employing a mode shape formulation for cantilever dynamics, simplifying calculations.
• Analyzing unimorph, dual layer bimorph, and triple layer bimorph configurations.

Main Results:

• The triple layer bimorph topology shows the highest theoretically achievable dynamic EMCF.
• Dual layer bimorphs outperform unimorphs, with a 9% improvement in dynamic EMCF at a 0.035 damping ratio.
• Layer thickness ratio and material stiffness are critical geometric and material design variables.

Conclusions:

• The triple layer bimorph is theoretically superior for maximizing dynamic EMCF.
• Design choices regarding passive layer stiffness and active material properties significantly impact dynamic EMCF.
• The developed model provides physical insight and numerical trends for piezoelectric actuator design.