Wavy-Thread Fiber Composite Joints for Rivet-Free Residual Strength

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Solution Overview

Problem

Current methods for connecting fiber composite components in aircraft construction, such as structural bonding and attaching add-on parts, often rely on rivets which increase weight and risk damage to load-bearing fibers, and lack sufficient residual strength in the event of adhesive failure.

Innovation Solution

A method for producing fiber composite components with wavy threads that protrude from the surface, allowing for enhanced adhesive anchoring and improved strength and reliability through form-fitting engagement in the adhesive layer, thereby reducing the need for rivets and enhancing damage tolerance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rivets are used to connect fiber composite components, then mechanical strength and reliability are improved, but weight increases and load-bearing fibers are damaged

Engineering Contradiction:
Improvemechanical strengthVSAvoidweight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent replaces the mechanical rivet connection system with a chemical adhesive bonding system. The adhesive layer bonds fiber composite components without requiring holes or mechanical fasteners, thereby eliminating the weight of rivets and avoiding damage to load-bearing fibers while maintaining connection strength through chemical adhesion.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the connection mechanism from mechanical (rivets) to chemical (adhesive bonding). This parameter change allows the transition from a system that requires physical penetration and mechanical interlocking to one that relies on molecular adhesion, thus avoiding fiber damage and reducing weight.

Inventive Principle:
Principle #35Parameter changes

2Weight of moving object

If adhesive connections are used to connect fiber composite components, then weight is reduced and fiber damage is avoided, but residual strength in the event of adhesive failure is insufficient

Engineering Contradiction:
ImproveweightVSAvoidresidual strength
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The patent uses a composite connection system combining organic adhesive and inorganic adhesive layers. The inorganic adhesive layer (e.g., ceramic-based) provides high-temperature stability and enhanced residual strength, while the organic layer provides strong initial bonding. This composite adhesive structure ensures reliability even under extreme conditions or partial failure.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies a primer layer before the adhesive layers to prepare the surface and enhance bonding. This preliminary step creates a transition layer that improves adhesion and provides a buffer against potential bonding failures, thereby cushioning against future reliability issues.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If rivets are used for structural bonding, then connection reliability is improved, but drilling dust exposure and corrosion risk increase

Engineering Contradiction:
Improveconnection reliabilityVSAvoiddrilling dust and corrosion risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical rivet system that requires drilling with a chemical adhesive bonding system. This substitution eliminates the drilling process entirely, thereby preventing the generation of drilling dust and the associated risks of corrosion and short circuits, while maintaining connection reliability through adhesive bonding.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Object-affected harmful factors

If adhesive connections are used instead of rivets, then damage to load-bearing fibers is reduced, but adhesive bond failure risk increases

Engineering Contradiction:
Improvefiber damageVSAvoidadhesive bond reliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent employs a composite adhesive system with multiple layers (primer, organic adhesive, inorganic adhesive) to enhance bond reliability. The inorganic adhesive layer provides high-temperature stability and strength, compensating for the potential weakness of single-layer adhesive bonds, thereby ensuring reliability without requiring damaging mechanical fasteners.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies different adhesive materials with specific properties to different functional requirements: the primer layer for surface preparation and initial adhesion, the organic adhesive for flexible bonding, and the inorganic adhesive for high-temperature stability and strength. This local differentiation of material properties optimizes both fiber protection and bond reliability.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2993030B1Fiber composite component, adhesive fitting for fiber composite components, and method for manufacturing a fiber composite component and an adhesion assembly
Publication Date: 2018.12.05 AIRBUS DEFENCE & SPACE GMBH
  • EP2993030B1 patent drawingFigure 1~2
  • EP2993030B1 patent drawingFigure 3~4
  • EP2993030B1 patent drawingFigure 5~6

AI summary

The present invention relates to a fiber composite component (10) comprising a composite (12) of hardened matrix material and fiber material (14) embedded therein. According to the invention, at least one thread (16) is provided in at least one partial area of ​​the fiber composite component (10) and extends in a wavy manner along a surface area (18) of the composite (12) in such a way that sections (16-1, 16-2 ) of the thread (16) run alternately within the composite (12) and outside of the composite (12). The invention also relates to an adhesive arrangement (1) for such fiber composite components (10, 10). Finally, the invention relates to a method for producing such a fiber composite component (10) or for producing such an adhesive arrangement (1). The invention shows a new way of creating an adhesive arrangement for fiber composite components, with which improved strength and reliability can be achieved.