Piezoelectric Transducer Shear Mode Design

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Solution Overview

Problem

Low frequency transducers often exhibit low coupling coefficients and reactive loads, leading to larger and more power-consuming power amplifiers, and struggle to maintain performance under hydrostatic pressure in compact forms.

Innovation Solution

An electroacoustic transducer design featuring a tail mass, a head mass, and parallelepiped-shaped piezoelectric material elements with non-zero d3y shear coefficients, made from materials like PMN-PT, which allows for high coupling coefficients, compact size, and resistance to hydrostatic pressure by utilizing shear mode properties and specific electrode configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If low frequency transducers use traditional mechanical systems to generate large displacements, then displacement is improved, but coupling coefficient deteriorates and device complexity increases

Engineering Contradiction:

ImprovedisplacementVSAvoidcoupling coefficient

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The patent replaces traditional mechanical displacement generation systems with piezoelectric material elements that directly convert electrical energy to mechanical displacement. The piezoelectric elements are coupled between the tail mass and head mass, eliminating complex mechanical systems while achieving large displacements at low frequencies with high coupling coefficients.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs composite material elements comprising piezoelectric material with non-zero d3y shear piezoelectric coefficients. These composite elements integrate multiple functional properties (piezoelectric effect, shear mode operation) to simultaneously achieve large displacement and high coupling coefficient without requiring separate mechanical systems.

Inventive Principle:

Principle #40Composite materials

2Length of moving object

If low frequency transducers use traditional designs, then displacement is improved, but power consumption increases due to reactive loads

Engineering Contradiction:

ImprovedisplacementVSAvoidpower consumption

Core Design Contradiction:

Length of moving objectVSUse of energy by moving object

Solution Approach 1:

By replacing traditional mechanical systems with piezoelectric material elements, the patent eliminates reactive loads that cause excessive power consumption. The piezoelectric elements provide direct electromechanical coupling that operates efficiently without the energy losses associated with reactive components in traditional mechanical systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Volume of moving object

If transducers are made compact, then device size is improved, but resistance to hydrostatic pressure deteriorates

Engineering Contradiction:

Improvedevice sizeVSAvoidresistance to hydrostatic pressure

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent uses piezoelectric material elements with specific crystallographic orientations (non-zero d3y shear coefficients) that provide inherent mechanical strength and pressure resistance. The composite structure of these elements maintains structural integrity under hydrostatic pressure while enabling compact transducer design, eliminating the need for larger pressure-resistant housings.

Inventive Principle:

Principle #40Composite materials

4Power

If transducers operate at low frequency with high output power, then power output is improved, but displacement requirement increases

Engineering Contradiction:

Improveoutput powerVSAvoiddisplacement requirement

Core Design Contradiction:

PowerVSLength of moving object

Solution Approach 1:

The piezoelectric material elements with non-zero d3y shear coefficients provide high strain output capability that enables large displacements at low frequencies. This material property allows the transducer to achieve high output power without requiring excessively large displacement amplitudes, as the piezoelectric materials efficiently convert electrical energy to mechanical work.

Inventive Principle:

Principle #40Composite materials

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

The transducer achieves a high coupling coefficient, compact size, and improved resistance to hydrostatic pressure, reducing power amplifier size and maintaining performance across a broad frequency range while withstanding increased pressure.

Implementation Method 1

The at least two parallelepiped shaped piezoelectric material elements are made from a piezoelectric material having a non-zero d3y shear piezoelectric coefficient

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS7615912B2Acoustic transducer

Publication Date: 2009.11.10 THE PENN STATE RES FOUND INC

AI summary

An electroacoustic transducer having a tail mass, a head mass and at least two parallelepiped shaped piezoelectric material elements disposed between and attached to the tail mass and the head mass is provided. The tail mass has a body extending between a first end and a second end, the body having a cavity with a cavity wall and the cavity extending from the first end towards the second end. The head mass has a head and an elongated shaft attached to and extending from the head, the shaft having a shaft axis and being located at least partially within the cavity of the tail mass. The at least two parallelepiped shaped piezoelectric material elements are made from a piezoelectric material having a non-zero d3y shear piezoelectric coefficient where the d3y coefficient can be d34, d35 or d36.