Thermoplastic Aircraft Engine Component Repair via Welding

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Solution Overview

Problem

Aircraft engine components made of thermoplastic materials often suffer from cracking due to high stress and temperature variations, leading to limited repair options that fail to maintain mechanical strength, resulting in costly replacements rather than reliable repairs.

Innovation Solution

The method involves using a welding technique with a heat source, such as a hot air nozzle, to join damaged thermoplastic components with filler material of the same type, processed into granulate and extruded into rods, ensuring strong and durable repairs by minimizing composition differences and eliminating hazardous cutting steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If composite tape or glue technique is used to repair cracks, then small cracks can be healed, but heavy damages cannot be effectively repaired and mechanical strength is insufficient

Engineering Contradiction:

Improverepairability of cracksVSAvoidmechanical strength of repaired part

Core Design Contradiction:

Ease of repairVSStrength

Solution Approach 1:

The patent changes the fundamental parameter of the repair method from chemical bonding (glue/composite tape) to thermal bonding (welding). By applying heat to melt the thermoplastic material and filler rod, the repair process transforms the bonding mechanism, enabling effective repair of heavy damages while achieving sufficient mechanical strength through fusion and consolidation of materials.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If thermoplastic components are replaced by new parts, then safety requirements are met, but costs increase significantly

Engineering Contradiction:

Improvesafety complianceVSAvoidcost of replacement

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent applies the self-service principle by using the damaged component itself as the source of repair material. The thermoplastic material from the damaged component is melted and reused as filler material for the repair, eliminating the need for expensive external filler materials and reducing waste. This self-repair approach maintains safety standards while significantly reducing replacement costs.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Instead of discarding the damaged thermoplastic component entirely, the patent recovers and reuses its material for repair purposes. The damaged component serves dual purposes: as the structure to be repaired and as the source of filler material, thereby reducing the need for new materials and lowering overall costs while maintaining safety requirements.

Inventive Principle:

Principle #34Discarding and recovering

3Strength

If welding technique is used to repair thermoplastic components, then mechanical strength is maintained, but the process complexity increases

Engineering Contradiction:

Improvemechanical strength of repaired partVSAvoidwelding process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary substance - the filler rod made of thermoplastic material - that facilitates the welding process. This filler material serves as a mediator between the heat source and the damaged component, enabling controlled melting and fusion while simplifying the overall process compared to direct welding techniques.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Loss of substance

If filler material of different composition is used, then repair cost is reduced, but mechanical strength and durability decrease

Engineering Contradiction:

Improverepair costVSAvoidmechanical strength of repaired part

Core Design Contradiction:

Loss of substanceVSStrength

Solution Approach 1:

The patent applies homogeneity by using filler material with the same chemical composition and physical properties as the original thermoplastic component. This ensures that the repaired area has uniform material properties throughout, maintaining consistent mechanical strength, durability, and thermal characteristics, while avoiding the costs associated with specialized filler materials.

Inventive Principle:

Principle #33Homogeneity

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 significantly enhances the durability and mechanical strength of repaired components, allowing for more extensive damage repair and extending the service life of aircraft engine components while meeting safety standards.

Implementation Method 1

heating the damaged component and the filler material to a temperature sufficient to melt the filler material

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

pressing the melted filler material into the damaged component to form a welded joint

Methodology Applied

Scientific EffectWelding: Welding

Data Source

PatentEP3178639B1Method of repairing damages of aircraft engine components made of weldable thermoplastic materials

Publication Date: 2021.09.22 MTU AERO ENGINES GMBH

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Figure 4~5

AI summary

The present invention relates to a method of repairing damages of an aircraft engine component made of weldable thermoplastic material(s), including welding of the weld filler material, preferably of the same material as the repaired component, into an initially prepared damage are such as cracked surface. The invention relates also to use of plastic welding technique for repairing damaged aircraft engine components made of weldable thermoplastic materials.