Electroactive Polymer Rivets for Fast Composite Airframe Joining

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Solution Overview

Problem

The riveting process for joining primary parts in composite airframes is time-consuming, noisy, and hinders weight reduction, while traditional methods lack efficiency and redundancy.

Innovation Solution

A method using electroactive polymer (EAP) fasteners is employed, where openings are created in fiber composite parts, exposing fibers, and the EAP is activated to reduce diameter for insertion, then deactivated to engage the fibers, forming a flush connection without tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional riveting is used to join fiber composite parts, then reliable and accurate joining is achieved, but the process becomes time-consuming and reduces productivity

Engineering Contradiction:

Improvejoining reliabilityVSAvoidfastening speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces traditional mechanical riveting systems with electroactive polymer (EAP) fasteners that are activated by electrical fields. The EAP material undergoes shape change when voltage is applied, enabling the fastener to expand and engage with the composite parts through electro-mechanical coupling rather than mechanical impact, thus improving productivity while maintaining reliability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes the ability of electroactive polymer material to change its physical parameters (shape, volume, diameter) in response to electrical field parameters. By controlling the voltage applied to the EAP fastener, the system can dynamically adjust the fastener's dimensions to achieve proper engagement with the composite parts, enabling faster and more reliable joining

Inventive Principle:

Principle #35Parameter changes

2Reliability

If traditional riveting is used to join primary parts, then high safety and redundancy are achieved, but weight reduction is prevented

Engineering Contradiction:

Improvesafety and redundancyVSAvoidairframe weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent employs electroactive polymer material for the fasteners, which is a composite material exhibiting both electrical and mechanical properties. This allows the fastener to be lighter than traditional metal rivets while still providing the necessary mechanical engagement and safety through its ability to change shape in response to electrical activation

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The replacement of heavy mechanical riveting systems with lighter electroactive polymer fasteners reduces overall airframe weight. The EAP material's ability to provide mechanical engagement through electrical activation eliminates the need for heavy-duty metal fasteners while maintaining the required safety and redundancy levels

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If traditional riveting is used, then proven joining method is applied, but noise is generated and weight reduction is hindered

Engineering Contradiction:

Improveproven method reliabilityVSAvoidnoise

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent replaces noisy mechanical riveting processes with silent or low-noise electrical activation of EAP fasteners. The electro-mechanical coupling mechanism eliminates the loud mechanical impact and hammering associated with traditional riveting, significantly reducing noise generation while maintaining manufacturing reliability

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

This method provides efficient, tool-free fastening with reduced weight and noise, enabling flush surfaces and high shear transfer, suitable for aircraft components.

Implementation Method 1

a fastener (36), that includes electroactive polymer material, is switchable between an activated and a deactivated state

Methodology Applied

Scientific EffectElectroactive polymer: Electroactive Polymer

Implementation Method 2

step b) comprises evaporating the matrix material. Preferably, step a) comprises cutting the opening into the first and second fiber composite part. the matrix material is evaporated by electromagnetic radiation, preferably laser radiation

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS12420952B2Method for fastening a part to another part using electrically deformable rivets

Publication Date: 2025.09.23 AIRBUS OPERATIONS GMBH

AI summary

Methods for fastening two fiber composite parts to each other with a fastener that includes electroactive polymer material. The parts have an opening within an inner circumferential surface. Fibers protrude from the inner circumferential surface into the opening and interlock with chains of micrograins of the electroactive polymer material. The fastener may switch between an activated state and a deactivated state and in the deactivated state, the fastener engages the exposed fibers.