Piezoelectric Bimorph Actuator with Curved Composite Mount

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Solution Overview

Problem

Piezoelectric bimorph actuators face restricted extension and contraction due to rigid mounting, leading to reduced free displacement and inconsistent resonate frequency, and alternative sliding mounts suffer from friction-related performance issues.

Innovation Solution

A piezoelectric bimorph actuator with an integral compliant boundary featuring a curved composite layer between two piezoelectric disks, allowing for flexible attachment and extension/contraction, fabricated using a molding process with a carbon fiber and epoxy resin matrix, providing a flexible mount that enables free movement while maintaining attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a rigid mounting structure is used to clamp the bimorph actuator, then the actuator is securely attached, but the extension and contraction of the bimorph is restricted, reducing free displacement

Engineering Contradiction:

Improvemounting strengthVSAvoidfree displacement

Core Design Contradiction:

StrengthVSLength of moving object

Solution Approach 1:

The patent applies this principle by using a flexible mounting structure with a curved interface portion that can deform elastically. The flexible mounting structure includes a curved surface that complements the curved interface portion of the bimorph, allowing the bimorph to extend and contract while maintaining secure attachment. This resolves the contradiction by providing both mounting strength and free displacement capability.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent changes the geometric parameters of the mounting structure by introducing a curved interface portion with specific radius of curvature. This curved geometry allows the mounting structure to accommodate the expansion and contraction movements of the bimorph while maintaining secure attachment, thus enabling both strong mounting and free displacement.

Inventive Principle:

Principle #35Parameter changes

2Strength

If a rigid clamp is used to mount the bimorph actuator, then secure attachment is achieved, but the clamping force is not repeatable, causing variance in resonate frequency

Engineering Contradiction:

Improveattachment securityVSAvoidresonate frequency consistency

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The flexible mounting structure with curved interface portion provides consistent elastic deformation that ensures repeatable clamping force. The flexibility allows the mounting to self-adjust and maintain uniform contact pressure, eliminating the variance in resonate frequency that occurs with rigid clamps.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The curved interface portion with specific radius of curvature enables the mounting structure to distribute clamping force uniformly across the bimorph surface. This curved geometry ensures repeatable contact and consistent clamping force, thereby maintaining reliable resonate frequency.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Length of moving object

If a sliding surface is provided for the bimorph mount to reduce restriction, then extension and contraction is improved, but friction reduces actuator performance

Engineering Contradiction:

Improveextension and contraction freedomVSAvoidactuator performance

Core Design Contradiction:

Length of moving objectVSLoss of energy

Solution Approach 1:

The flexible mounting structure eliminates the need for sliding surfaces by providing a compliant interface that moves with the bimorph. This flexible connection maintains continuous contact without relative sliding, thereby avoiding friction losses while still allowing full extension and contraction freedom.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent replaces the mechanical sliding contact system with a flexible elastic connection. This substitution eliminates friction-based energy losses associated with sliding surfaces while maintaining the ability of the bimorph to extend and contract freely during operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution allows for robust and flexible mounting of the bimorph actuator, enhancing its operational displacement and reducing variance in resonate frequency by providing a consistent clamping force without the drawbacks of friction, thus improving overall performance.

Implementation Method 1

Piezo electric bimorph actuators are employed for various applications including synthetic jet generators for active flow control on aerodynamic surfaces

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

The curved section provides a mount which allows attachment of the bimorph while allowing the bimorph to extend and contract during operation

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP3480864B1A method for fabrication of a piezoelectric bimorph actuator with an integral compliant boundary

Publication Date: 2020.05.13 THE BOEING CO

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Figure 4A

AI summary

A piezoelectric bimorph actuator (16) with an integral compliant boundary employs a first piezoelectric element (22a), a second piezoelectric element (22b) and a composite layer (20) intimately engaged between the first and second piezoelectric elements (22a, 22b) to form a bimorph actuator (16). The composite layer (20) extends from a peripheral edge of the piezoelectric elements (22a, 22b and has a curved interface portion (24) providing a mount for attachment of the bimorph actuator (16).