Insulating Fastener Cover for Composite Delamination Prevention

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Solution Overview

Problem

Composite materials in aircraft structures are prone to delamination due to heat exposure, particularly at the interface between composite and metallic fasteners, which can lead to detachment and separation.

Innovation Solution

An insulating washer and cover system is introduced, where the cover is secured to the washer's peripheral edge, creating an insulating volume that reduces heat transfer to the fastener and composite structure, using materials like ceramic fibers and elastomer layers to prevent heat conduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metallic fasteners are used to attach composite materials, then structural strength and assembly capability are improved, but heat conduction causes delamination at the interface between composite and fastener

Engineering Contradiction:

Improvestructural strengthVSAvoidheat conduction

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

An insulating cover is introduced as an intermediary component between the metallic fastener and the composite material. This cover is made of thermally insulating material that blocks heat conduction paths while allowing the fastener to maintain its structural function. The cover directly contacts both the fastener and composite material, serving as a thermal barrier that prevents heat-induced delamination.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The insulating cover is constructed from composite materials that combine thermal insulation properties with mechanical strength requirements. By using composite material for the cover itself, the solution maintains structural integrity while providing thermal protection, thus resolving the contradiction between strength and heat conduction.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If insulating material is added to the fastener system, then heat conduction is reduced, but device complexity increases

Engineering Contradiction:

Improveheat conductionVSAvoidfastener system complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The insulating cover is merged with the existing fastener system by being directly attached to the fastener body or integrated into the assembly process. This combining approach allows the insulating function to be added without creating a separate, complex subsystem. The cover becomes an integral part of the fastener assembly, simplifying the overall system while providing thermal protection.

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

The solution effectively reduces heat conduction through the fastener, minimizing the likelihood of delamination and extending the service life of composite structures by maintaining a protective insulation barrier.

Implementation Method 1

an insulating volume is created with the cover secured to the insulating washer

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS9027223B2Insulating cover for fasteners used in high temperature environments

Publication Date: 2015.05.12 THE BOEING CO

AI summary

A method and apparatus for an insulating cover for fasteners. In one advantageous embodiment, an apparatus comprises a washer and a cover. The washer is capable of receiving a fastener. The cover is capable of being secured to the insulating washer, wherein an insulating volume is created with the cover secured to the washer.