Single-Poled Shear Mode Transducer for High-Field Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bender bars for underwater electroacoustic transducers require complex manufacturing due to the use of double-poled piezoelectric crystal elements, and existing shear mode piezoelectric elements face de-polarization issues under high drive conditions.
Innovation Solution
A shear mode transducer is constructed using a single layer of 36-shear mode piezoelectric single crystals poled along a single direction, with electrodes applied only on the outer surfaces, inducing longitudinal-flexure electromechanical motion through a voltage difference across the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional double-poled piezoelectric crystal elements are used in bender bars, then the transducer can generate mechanical motion, but the manufacturing process becomes complex
Solution Approach 1:
The invention extracts and eliminates the need for double-poled piezoelectric crystal elements by using single-poled elements in shear mode. This removes the complex manufacturing steps associated with creating and assembling double-poled elements, while still achieving the required mechanical motion through shear deformation of single-poled crystals.
Solution Approach 2:
The invention changes the operational mode from longitudinal expansion/contraction to shear mode deformation. This parameter change allows single-poled elements to replace double-poled elements, simplifying manufacturing while maintaining the ability to generate mechanical motion in bender bar transducers.
2Reliability
If other shear mode piezoelectric elements (15-shear or 24-shear modes) are used, then shear motion can be produced, but de-polarization occurs under high drive conditions
Solution Approach 1:
The invention uses composite piezoelectric crystal structures with specific crystallographic orientations (such as PMN-PT or PZN-PT single crystals with particular axis alignments) that combine high piezoelectric coefficients with resistance to de-polarization. This allows the transducer to withstand high AC electric fields without losing polarization, enabling high-power operation.
Solution Approach 2:
The invention applies electric fields locally along the poling direction in shear mode configuration, which optimizes the stress distribution within the crystal lattice. This local field application method prevents the formation of reverse domains that cause de-polarization, while still achieving the necessary shear motion for high-power operation.
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 simplifies the construction of electroacoustic devices and enhances material properties, allowing for higher AC electric fields and improved performance in underwater applications by minimizing de-polarization risks.
Implementation Method 1
piezoelectric single crystals to excite longitudinal flexure electromechanical motion
Data Source
AI summary
Piezoelectric materials are utilized in shear mode deformation to excite longitudinal flexural bending electromechanical motion in a transducer. A single transducer stack comprising a plurality of shear mode piezoelectric material elements are arranged to create a flexural bender bar which can be used for electroacoustic applications. The transducer stack is configured such that adjacent piezoelectric elements have opposite shear mode deformation. Electrodes for positive and negative voltage excitation are applied to parallel faces of the piezoelectric elements. Application of a voltage difference between the electrodes causes the piezoelectric elements to undergo shear strain, wherein one half of the transducer stack expands into tension and the other half contracts into compression, thus inducing longitudinal flexural bending electromechanical motion. Enclosed embodiments provide support structures for utilization of piezoelectric shear mode induced longitudinal flexural bending electromechanical motion.