Multilayer piezocomposite structures with piezoceramic volume fractions determined by mathematical optimisation

Area of Science:

• Materials Science
• Acoustics
• Engineering

Background:

• Piezocomposite materials are crucial for broadband underwater sonar, offering advantages over traditional piezoceramics.
• Single-layer piezocomposites face limitations in effective operation below 100 kHz.
• Multilayer composite stacks present a solution, with performance heavily influenced by layer-specific ceramic volume fractions.

Purpose of the Study:

• To theoretically investigate 1-3 piezocomposite transducers with multilayer structures.
• To optimize the ceramic volume fraction in each layer of a five-layer stack.
• To maximize the gain-bandwidth product for enhanced transducer performance.

Main Methods:

• Development of custom computer code to solve the one-dimensional wave equation using matrix manipulation.
• Utilizing PZ Flex finite element analysis for additional support.
• Application of simulated annealing, a stochastic optimization technique in MATLAB, to determine optimal volume fractions.
• Defining the cost function as the maximization of the gain-bandwidth product.

Main Results:

• Significant increases in the gain-bandwidth product were achieved through optimized, layer-specific volume fractions.
• Performance gains far exceeded those previously reported with trial-and-error methods.
• The optimized multilayer designs show potential for substantial improvements in practical device performance.

Conclusions:

• Optimizing ceramic volume fractions in multilayer piezocomposite transducers is a viable strategy for enhancing performance.
• This approach offers a pathway to overcome limitations of single-layer devices for low-frequency underwater sonar.
• The findings suggest practical improvements in device sensitivity and frequency response are attainable.