Blade-and-Slot Composite Panel Joints With Internal Adhesive Bonding

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Solution Overview

Problem

Joining composite panels with a core to achieve structural strength while minimizing adhesive usage, particularly in aerospace applications, is challenging due to the complexity of uniting panels with desired structural integrity and the need to reduce adhesive weight for improved fuel efficiency.

Innovation Solution

The method involves cutting slots into composite panels with a core, inserting a blade into these slots, and securing it with adhesive, which penetrates into the core cells, providing a strong and aesthetically pleasing joint with minimal adhesive exposure and weight addition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If adhesive is used to join composite panels, then structural strength is achieved, but joint weight increases reducing fuel efficiency

Engineering Contradiction:
Improvejoint structural strengthVSAvoidjoint weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The core material is designed with a porous or cellular structure that allows adhesive to penetrate and infiltrate throughout the volume. This creates extensive internal bonding surfaces and mechanical interlocking, achieving high joint strength while using minimal adhesive material, thereby reducing joint weight for improved fuel efficiency

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

The adhesive is nested within the porous core structure itself, with the core acting as a container and delivery mechanism for the adhesive. This internal placement eliminates the need for external adhesive applications and reduces the overall joint footprint

Inventive Principle:
Principle #7Nested doll (Nesting)

2Strength

If more adhesive is used to ensure structural integrity, then joint strength improves, but adhesive cleanup becomes more difficult and time-consuming

Engineering Contradiction:
Improvejoint structural strengthVSAvoidadhesive cleanup ease
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The adhesive application process is extracted from the external surface and relocated to the internal porous structure of the core. By pre-saturating the core with adhesive before panel assembly, excess adhesive is contained within the core volume and does not require post-assembly cleanup from external surfaces

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The core is pre-saturated with adhesive before the panels are assembled together. This preliminary action ensures that the adhesive is already in position and properly distributed within the core structure, eliminating the need for adhesive application after assembly and simplifying the manufacturing process

Inventive Principle:
Principle #10Preliminary action

3Strength

If adhesive is applied externally to join panels, then bonding strength is achieved, but aesthetic appearance is compromised due to visible adhesive

Engineering Contradiction:
Improvejoint bonding strengthVSAvoidjoint aesthetic appearance
Core Design Contradiction:
StrengthVSShape

Solution Approach 1:

The adhesive is nested within the porous core structure, which is itself nested within the panel assembly. This hierarchical nesting conceals the adhesive from external view while maintaining its bonding function, achieving both strength and aesthetic appearance

Inventive Principle:
Principle #7Nested doll (Nesting)

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 blade-and-slot system enhances mechanical strength, simplifies assembly, reduces adhesive cleanup, and maintains a fire-resistant joint, suitable for aircraft interiors by utilizing internal bonding and minimizing external adhesive presence.

Implementation Method 1

driving adhesive into cells within the core of the first composite panel; driving adhesive into cells within the core of the second composite panel

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP3398755B1Blade-and-slot joints that unite composite panels via internal blades and method
Publication Date: 2021.11.10 THE BOEING CO
  • EP3398755B1 patent drawingFigure 1
  • EP3398755B1 patent drawingFigure 2
  • EP3398755B1 patent drawingFigure 3

AI summary

Method and system for assemblying two composite panels (110, 120) includes cutting a first slot (310) into a first composite panel that includes a core (112) between two facesheets (114). The first slot penetrates through the core of the first composite panel. The method also includes cutting a second slot (320) into a second composite panel that includes a core between two facesheets. The second slot penetrates through a facesheet of the second composite panel as well as the core of the second composite panel. The method further includes inserting a blade into the first slot, and inserting the blade into the second slot.