Thermoplastic Sensor Foil for Joining Fiber-Reinforced Plastics

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Solution Overview

Problem

Current methods for joining fiber-reinforced plastic structural elements are costly, labor-intensive, and do not effectively achieve weight savings while maintaining the integrity of the fiber structure, often requiring complex processes and additional holding means.

Innovation Solution

A method involving the use of a thermoplastic sensor foil element that dissolves and re-crosslinks during the curing process of the structural elements, forming a robust intermediate phase between them, which reduces complexity and effort, and incorporates sensors for monitoring structural health.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional joining methods (adhesives, rivets, stiffening means) are used to join fiber-reinforced plastic structural elements, then the structural integrity and strength can be maintained, but the production cost increases, manufacturing complexity increases, and weight increases

Engineering Contradiction:
Improvejoint strengthVSAvoidjoining process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent combines the joining function and sensor integration into a single thermoplastic film element. This film serves both as the joining medium (replacing separate adhesives and mechanical fasteners) and as the sensor carrier, eliminating multiple components and simplifying the overall joining system while maintaining structural integrity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The thermoplastic film element performs multiple functions simultaneously: it acts as the joining medium to bond structural elements, provides structural reinforcement, and serves as the substrate for sensor integration. This multi-functionality eliminates the need for separate joining means and reduces overall system complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If additional holding means (rivets, stiffening means) are added to structural elements to ensure joint integrity, then the reliability of the connection improves, but the weight increases and manufacturing effort increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidcomponent weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent merges the holding function into the thermoplastic film itself, which provides both the bonding capability and the structural reinforcement needed for reliable connections. This eliminates the need for separate rivets or stiffening means, thereby reducing weight while maintaining connection reliability

Inventive Principle:
Principle #5Merging (Combining)

3Strength

If sensor elements are bonded separately to structural elements after joining, then structural integrity is maintained, but additional manufacturing steps are required and production complexity increases

Engineering Contradiction:
Improvestructural integrityVSAvoidmanufacturing efficiency
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The patent incorporates the sensor carrier function into the thermoplastic film before the joining process begins. The sensor elements are already integrated onto the film that will serve as the joining medium, eliminating the need for separate post-joining sensor installation steps and streamlining manufacturing

Inventive Principle:
Principle #10Preliminary action

4Reliability

If complex joining processes with multiple steps are used to join fiber-reinforced plastic elements, then the quality and durability of joints can be ensured, but the production time increases and cost increases

Engineering Contradiction:
Improvejoint durabilityVSAvoidproduction time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent combines multiple functions (joining, sensing, and structural reinforcement) into a single integrated thermoplastic film element that is applied in one step. This eliminates multiple sequential manufacturing steps while ensuring joint durability through the film's inherent properties and the integration of sensor monitoring

Inventive Principle:
Principle #5Merging (Combining)

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 approach results in a strong, durable, lightweight joint with reduced production effort and cost, enabling real-time monitoring of structural integrity and potential damage detection, thus optimizing the cost-weight ratio and extending maintenance intervals.

Implementation Method 1

the sensor foil element is first dissolved under the influence of heat

Methodology Applied
Scientific EffectDissolution:

Implementation Method 2

and then crosslinked again and thereby connected to the matrix of the structural elements

Methodology Applied
Scientific EffectCrosslinking:

Implementation Method 3

The joining process between the structural elements that takes place by means of the at least one sensor film element is a type of film diffusion welding process in which an amorphous thermoplastic is advantageously formed as a robust intermediate phase between the resin systems of the structural elements

Methodology Applied
Scientific EffectFilm diffusion welding: Diffusion Welding

Data Source

PatentEP3257655B1Sensor intigration during the joining of strucutral parts
Publication Date: 2019.10.16 AIRBUS DEFENCE & SPACE GMBH
  • EP3257655B1 patent drawingFigure 1

AI summary

The invention relates to a method for joining structural elements (1) to form a component made of at least one fiber-reinforced plastic, comprising the process steps of: providing at least two structural elements (1) made of at least one fiber-reinforced plastic with a respective matrix; providing at least one film element (5) made of a high-performance thermoplastic; arranging the at least one film element (5) on a surface of one of the structural elements (1) or between surfaces to be joined of the at least two structural elements (1) to be joined and producing the component to be joined in a curing process.