End-Driven Bender Transducer for Low-Frequency Acoustic Output
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Solution Overview
Problem
Existing low-frequency underwater sound transducers face challenges in achieving a low resonant frequency and high output level within a fixed volume, as they require a compliant structure and specific piezoelectric material distribution, limiting the choice of materials for the bending beam and efficiency of acoustic radiation.
Innovation Solution
The use of piezoelectric end supports driven in opposite directions creates a leveraged bending motion in the bending beam or disc, allowing for a wide choice of materials and increased radiation area, with options including bilaminar, tri-laminar configurations, and convex or concave extensions to optimize bandwidth and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the piezoelectric material is located as part of the bending beam, then the transducer can achieve low resonance frequency, but the choice of materials for the bending beam is limited and the mechanical Q is reduced
Solution Approach 1:
The transducer is divided into two functional segments: piezoelectric end supports that generate the driving force, and a separate bending beam that provides the compliant radiating structure. This segmentation allows the bending beam to be made from materials optimized for acoustic radiation (such as aluminum or steel) rather than being constrained by piezoelectric material requirements, while the piezoelectric supports handle the electrical-to-mechanical conversion function.
Solution Approach 2:
The piezoelectric material is extracted from the bending beam and relocated to the end supports. This extraction allows the bending beam to be constructed from non-piezoelectric materials with superior acoustic radiation properties, while the piezoelectric material performs its function in the supports where it can effectively drive the bending motion without compromising the beam's mechanical quality factor.
2Adaptability or versatility
If the length of the bending beam is increased to achieve low resonance frequency, then the resonance frequency decreases rapidly, but the device volume increases
Solution Approach 1:
The system uses the dynamic bending motion of the beam rather than relying solely on increasing beam length to achieve low resonance frequency. The piezoelectric end supports create opposing motions that dynamically bend the beam, allowing the resonance frequency to be controlled through the bending stiffness and support conditions rather than just the beam length, thereby reducing the required device volume.
Solution Approach 2:
Instead of changing only the length parameter of the bending beam, the invention changes multiple parameters including the piezoelectric material properties, end support conditions, and beam stiffness characteristics. This multi-parameter optimization allows achieving low resonance frequency without proportionally increasing the device volume, as the resonance frequency can be tuned through material and structural parameter adjustments.
3Productivity
If piezoelectric end supports are used to drive the bending beam, then the acoustic output and bandwidth are enhanced, but the device complexity increases
Solution Approach 1:
The piezoelectric end supports serve multiple functions simultaneously: they provide the driving force for the bending beam, act as structural supports for the beam, and can be configured to provide both extension and bending modes of motion. This multi-functionality reduces the need for separate components, thereby enhancing acoustic output and bandwidth while limiting the increase in overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the acoustic output and bandwidth by leveraging the motion of the bending beam, achieving a low resonance frequency and increased radiation area, while allowing for the use of various materials and configurations to optimize performance.
Implementation Method 1
electrically driven by piezoelectric material, with inner and outer parts driven in opposite directions at supporting ends of the beam
Implementation Method 2
creating a bending motion of the beam radiating into the water or other medium
Data Source
AI summary
An underwater acoustic transducer that is capable of radiating acoustic energy at low frequencies. A transducer which is a resonant low frequency bender-type transducer driven at its end supports by a piezoelectric stack of material operating with inner and outer parts driven in opposite directions creating a bending motion of a radiating beam, plate or disc. The small piezoelectric motions at the beam supports are magnified by the leveraged motion of the bending beam(s) creating significant output at low frequencies.