Co-Bonded Fiber-Reinforced Composite Components With Slotted Transitions

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Solution Overview

Problem

Existing methods are unsuitable for manufacturing a fully bonded one-shot composite component suitable for use as a T-tail horizontal stabilizer of a helicopter, as they do not account for thermal tooling expansion and resulting stresses on pre-cured composite elements with out-of-plane shapes.

Innovation Solution

A method involving a pre-cured fiber reinforced composite support structure with slots for flexibility, joined to uncured elements using a co-bonding process in a blow molding tool, allowing thermal expansion without causing stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pre-cured fiber reinforced composite element with out-of-plane shape is joined using co-bonding process, then a fully bonded one-shot composite component is achieved, but thermal tooling expansion creates bending loads and stresses on the stiff and curved pre-cured element

Engineering Contradiction:
Improvefully bonded one-shot composite componentVSAvoidbending loads and stresses on pre-cured element
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The pre-cured composite element is segmented by introducing slots that divide the continuous curved structure into sections. These slots allow the element to be divided into flexible and stiff zones, enabling thermal expansion accommodation while maintaining structural integrity during co-bonding.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The physical state of the pre-cured element is changed by modifying its flexibility parameters through slot introduction. The slots transform the element from a completely rigid structure to one with controlled flexibility in specific zones, allowing it to withstand thermal expansion stresses during the co-bonding process.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If slots are introduced in the transition area of the pre-cured support structure, then bending flexibility is provided to accommodate thermal expansion, but the structural integrity may be compromised

Engineering Contradiction:
Improvebending flexibility for thermal expansionVSAvoidstructural integrity of support structure
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

Different areas of the pre-cured support structure are given different properties: the transition areas contain slots providing flexibility, while the flat and curved areas maintain full structural strength. This local differentiation allows the structure to have both flexibility where needed and strength where required.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The slots are pre-positioned in the transition areas before the co-bonding process. This preliminary arrangement of flexibility zones ensures that when thermal expansion occurs during curing, the structure can accommodate the expansion stresses without compromising overall integrity, as the flexible zones are already in place to handle the expected loads.

Inventive Principle:
Principle #10Preliminary action

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

Enables the production of a fiber reinforced composite component with complex shapes like T-tail horizontal stabilizers by mitigating thermal tooling stresses, ensuring a strong and flexible bond without distortion.

Implementation Method 1

thermal expansion of a respectively used tooling would create bending loads and stresses on the actually stiff and curved pre-cured RTM element

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

joining at least one uncured fiber reinforced composite element to at least one cured fiber reinforced composite element by means of curing the elements together in order to obtain a bond joint

Methodology Applied
Scientific EffectCuring: Chemical Bonding

Data Source

PatentEP4640411A1A method of manufacturing a fiber reinforced composite component
Publication Date: 2025.10.29 AIRBUS HELICOPTERS DEUT GMBH
  • EP4640411A1 patent drawingFigure 1
  • EP4640411A1 patent drawingFigure 2
  • EP4640411A1 patent drawingFigure 3

AI summary

The invention relates to a method of manufacturing a fiber reinforced composite component. The method comprises providing a pre-cured fiber reinforced composite support structure (13) which comprises a flat area (14c) that merges at at least one associated transition area (14d) into at least one annexed curved area (14a), wherein the at least one associated transition area (14d) comprises at least one slot (15a, 15b) adapted to provide bending flexibility to the at least one transition area (14d); providing at least one uncured fiber reinforced composite element; and joining the at least one uncured fiber reinforced composite element to the pre-cured fiber reinforced composite support structure (13) by means of a co-bonding process.