Partial-Cure Thermoset Composite Laminate Bonding Without Adhesives

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Solution Overview

Problem

Existing methods for joining composite laminate parts require extensive surface preparation, use of bonding adhesives, and specialized tooling, increasing manufacturing costs and weight, while limiting process efficiency.

Innovation Solution

Applying a resin curing accelerator strategically to selected regions of fiber-reinforced thermoset resin plies, allowing differential curing to create partially cured parts that maintain shape without additional support, enabling co-bonding or co-curing with uncured portions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If adhesive bonding or co-bonding is used to join composite parts, then bonding quality can be achieved, but surface preparation and adhesive selection increase manufacturing costs and weight

Engineering Contradiction:
Improvebonding qualityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the need for separate adhesives by integrating the bonding function directly into the composite material itself. Through resin tagging and partially cured regions, the composite part develops intrinsic bonding capabilities at its surfaces, removing the requirement for external adhesive materials while maintaining bonding quality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the structural composite material with the bonding function by creating partially cured regions that serve dual purposes: maintaining structural integrity while providing reactive surfaces for bonding. This consolidation eliminates the need for separate adhesive components and simplifies the manufacturing process.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If adhesive bonding or co-bonding is used to join composite parts, then bonding quality can be achieved, but surface preparation and elimination of surface contaminants increase manufacturing costs

Engineering Contradiction:
Improvebonding qualityVSAvoidsurface preparation process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs preliminary surface preparation by creating partially cured regions during the initial curing process. These regions are pre-configured with reactive resin tags that are ready for bonding, eliminating the need for subsequent surface preparation steps such as grinding, cleaning, or chemical treatment that would otherwise be required.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The composite material serves its own surface preparation needs through the formation of partially cured regions with exposed reactive resin. These regions automatically provide the necessary surface characteristics for bonding without requiring external intervention or separate preparation processes.

Inventive Principle:
Principle #25Self-service

3Reliability

If bonding adhesives are used to join composite parts, then bonding quality can be achieved, but undesired weight is added to part assemblies

Engineering Contradiction:
Improvebonding qualityVSAvoidpart assembly weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent extracts and removes the adhesive material from the bonding system, replacing it with intrinsic bonding capabilities developed within the composite structure itself through partially cured regions. This eliminates the additional weight that would be introduced by separate adhesive materials.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the curing parameter of the resin to create partially cured regions that maintain bonding capability. By controlling the degree of curing in specific areas, the material transitions from a fully cured rigid state to a partially cured state that retains chemical reactivity and bonding potential without requiring external adhesives.

Inventive Principle:
Principle #35Parameter changes

4Stability of the object's composition

If tooling is provided for supporting uncured parts during the joining process, then part stability can be maintained, but manufacturing costs are increased

Engineering Contradiction:
Improvepart stabilityVSAvoidmanufacturing cost
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent performs preliminary stabilization by creating partially cured regions that provide inherent structural support during the bonding process. These regions are pre-configured to maintain part geometry and stability, eliminating the need for external tooling or support fixtures that would otherwise be required to hold uncured parts in place.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The composite part provides its own support and stability functions through the partially cured regions. These regions act as self-supporting structures that maintain geometric integrity during handling and bonding operations, removing the need for separate tooling systems.

Inventive Principle:
Principle #25Self-service

5Reliability

If extensive surface preparation and bonding adhesives are used, then bonding quality can be achieved, but process efficiency is reduced

Engineering Contradiction:
Improvebonding qualityVSAvoidprocess efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent merges the structural composite material with the bonding function by creating partially cured regions that serve dual purposes: maintaining structural integrity while providing reactive surfaces for bonding. This consolidation eliminates the need for separate adhesive components and simplifies the manufacturing process.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts and eliminates the need for separate adhesives by integrating the bonding function directly into the composite material itself. Through resin tagging and partially cured regions, the composite part develops intrinsic bonding capabilities at its surfaces, removing the requirement for external adhesive materials while maintaining bonding quality.

Inventive Principle:
Principle #2Taking out (Extraction)

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

Eliminates the need for extensive surface preparation and bonding adhesives, reduces tooling costs, and allows for efficient assembly and curing without specialized equipment, while maintaining part stability through strategically cured regions.

Implementation Method 1

A first portion of the plurality of plies has a resin curing accelerator applied thereto. The resin curing accelerator promotes curing of the thermoset resin in the first portion of the plurality of plies

Methodology Applied
Scientific EffectCatalysis: Catalysis

Data Source

PatentEP3466632B1Partial curing of thermoset composites
Publication Date: 2025.07.02 THE BOEING CO
  • EP3466632B1 patent drawingFigure 1~2
  • EP3466632B1 patent drawingFigure 3
  • EP3466632B1 patent drawingFigure 4~7

AI summary

Composite laminate structures are produced using partially cured parts. Partial curing of the parts is achieved by applying a catalyst to regions of the parts that are to be fully cured. These regions cure at a lower-than-normal temperature while remaining regions of the part remain uncured, allowing them to be co-bonded or co-cured to other structures.