Injection-Bonded Joint With Segmented Adhesive Chambers

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Solution Overview

Problem

The unpredictability of adhesive flow in long length bondlines during the bonding process leads to undesirable results, requiring reworking or scrapping of bonded parts, increasing costs and complexity, and necessitating the use of anti-peel fasteners to prevent peeling, which adds weight and complexity to structural assemblies.

Innovation Solution

The method involves forming chamber walls within the bondline region to divide it into adhesive chambers, injecting structural adhesive through an injection port, and discharging excess adhesive through bleed holes, allowing for controlled adhesive flow and curing, thereby eliminating the need for mechanical fasteners and improving bond quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a long length bondline is used to join parts, then the bonding area is increased, but the adhesive flow becomes unpredictable leading to poor bond quality

Engineering Contradiction:

Improvebonding areaVSAvoidadhesive flow control

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The long bondline is divided into multiple discrete adhesive chambers separated by chamber walls. This segmentation allows each chamber to be filled and cured independently, ensuring predictable adhesive flow and complete void-free bonding across the entire long bondline area without the flow control problems associated with continuous long bondlines.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If traditional adhesive application methods are used, then the process is simple, but adhesive flow unpredictability requires reworking or scrapping bonded parts

Engineering Contradiction:

Improvebonding process simplicityVSAvoidbond joint quality

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The chamber walls are pre-formed within the bondline region before adhesive injection. This preliminary action creates predefined chambers that control adhesive flow paths, ensuring complete filling and void-free bonds. The systematic approach of pre-segmenting the bondline eliminates the need for reworking or scrapping parts due to adhesive flow issues.

Inventive Principle:

Principle #10Preliminary action

3Strength

If anti-peel fasteners are installed to prevent bondline peeling, then joint strength is improved, but the assembly weight and complexity increase

Engineering Contradiction:

Improvebond joint strengthVSAvoidassembly weight

Core Design Contradiction:

StrengthVSWeight of stationary object

Solution Approach 1:

The chamber walls and bondline dams create a self-contained adhesive containment system that maintains uniform adhesive distribution and prevents peeling at bondline edges. This self-service mechanism eliminates the need for additional anti-peel fasteners, reducing both assembly weight and complexity while maintaining bond joint strength through proper adhesive curing.

Inventive Principle:

Principle #25Self-service

4Manufacturing precision

If chamber walls are formed to divide the bondline, then adhesive flow control is improved, but the device complexity increases

Engineering Contradiction:

Improveadhesive flow predictabilityVSAvoidbondline structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The chamber walls act as intermediary structures that segment the bondline into manageable adhesive chambers. These intermediaries provide precise control over adhesive flow in each chamber while the injection ports and bleed holes serve as mediators for adhesive introduction and air evacuation. The systematic use of these intermediary elements achieves predictable adhesive flow with manageable structural complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 ensures predictable adhesive flow, reduces voids and air bubbles, enhances the strength and durability of bonded joints, eliminates the need for mechanical fasteners, and results in weight savings and improved manufacturing efficiency.

Implementation Method 1

injecting a structural adhesive into the adhesive chamber through an injection port

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

a structural adhesive injected into the adhesive chambers through at least one injection port to bond the first part to the second part

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS10458454B2Structural assembly having injection-bonded joint and method of forming

Publication Date: 2019.10.29 THE BOEING CO

AI summary

A method of forming an injection-bonded joint includes providing a first part and a second part having a second part upper edge and a second part lower edge, and forming a chamber wall within a bondline region between mating surfaces of the first part and the second part. The chamber wall divides a bondline length of the bondline region and defines at least one adhesive chamber. The method further includes forming a bondline dam along each of the second part upper edge and the second part lower edge in a manner such that the chamber wall, the bondline dams, and the mating surfaces collectively enclose the adhesive chamber having a chamber upper edge and a chamber lower edge. The method also includes injecting a structural adhesive into the adhesive chamber through an injection port and discharging excess adhesive from the adhesive chamber through a bleed hole.