Variable Thickness Acoustic Transducer for Broadband Signal Quality

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Solution Overview

Problem

Existing acoustic transducers in the energy industry face limitations in bandwidth, signal quality, and sensitivity, particularly in ultrasonic imaging applications, where fixed thickness transducers are inadequate for broad-band applications and often result in unwanted focusing and reflection issues.

Innovation Solution

A variable thickness acoustic transducer assembly is designed, featuring a piezoelectric active element with a curved back surface and a backing material that conforms to the shape, allowing for adjustable thickness and absorption of acoustic signals, thereby enhancing bandwidth and signal characteristics without focusing the transmitted signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a fixed thickness transducer is used, then the structure is simple and easy to manufacture, but the bandwidth is limited and signal quality deteriorates

Engineering Contradiction:

Improvetransducer structure simplicityVSAvoidbandwidth and signal quality

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The active element is designed with non-uniform thickness distribution, where different regions have different thicknesses to generate a broad-band frequency spectrum. This local variation in thickness allows the transducer to emit multiple frequencies simultaneously, improving bandwidth and signal quality without requiring multiple separate transducer elements.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The thickness parameter of the active element is deliberately varied across its structure rather than maintaining a constant value. By changing the thickness parameter spatially, the transducer achieves broadband frequency emission, resolving the contradiction between structural simplicity and performance requirements.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a curved back surface is introduced to achieve variable thickness, then bandwidth and signal quality improve, but manufacturing complexity increases

Engineering Contradiction:

Improvebandwidth and signal qualityVSAvoidtransducer structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The back surface of the active element is formed with a curved profile, creating variable thickness from the center to the edges. This curvature is achieved through standard ceramic forming techniques during manufacturing, allowing the complex shape to be produced in a single step without requiring multiple assembly operations or complex tooling.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If backing material is shaped to conform to the curved back surface, then acoustic signal absorption improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improveacoustic signal absorptionVSAvoidbacking material fit to curved surface

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The backing material is formed as a flexible layer that can conform to the curved back surface of the active element. This flexibility allows the backing material to adapt to the curved geometry without requiring high-precision machining or complex assembly procedures, while still maintaining intimate contact for effective acoustic energy absorption.

Inventive Principle:

Principle #30Flexible shells and thin films

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 variable thickness transducer provides superior bandwidth and signal quality, reducing unwanted vibrations and reflections, and increasing sensitivity, making it suitable for broad-band ultrasonic applications such as downhole measurements and formation evaluation.

Implementation Method 1

a piezoelectric active element configured to emit acoustic signals

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the shape configured to cause the active element to have a variable thickness between the emitting surface and the back surface

Methodology Applied

Scientific EffectVariable thickness resonance: Resonance

Implementation Method 3

a backing material disposed in contact with the backing surface and configured to absorb the acoustic signals

Methodology Applied

Scientific EffectAcoustic absorption: Acoustic Absorption

Data Source

PatentUS9597709B2Variable thickness acoustic transducers

Publication Date: 2017.03.21 BAKER HUGHES CO

AI summary

An embodiment of an acoustic transducer assembly includes: a piezoelectric active element configured to emit acoustic signals, the active element having an emitting surface and a back surface located opposite the emitting surface, at least a portion of the back surface having a shape that forms a curve, the shape configured to cause the active element to have a variable thickness between the emitting surface and the back surface; and a backing material disposed in contact with the backing surface and configured to absorb the acoustic signals, the backing material shaped to conform to the back surface.