Composite Radius Filler Integration for Accurate Stiffener Assembly

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Solution Overview

Problem

The manufacturing of composite parts with radius fillers and stiffeners is labor-intensive and time-consuming due to the difficulty in handling and positioning pre-formed fillers, especially with thermoplastics, which are rigid and hard to conform to compound contours, and the need for additional tooling and templates.

Innovation Solution

The method involves using an automated fiber placement (AFP) machine to integrate radius noodle fillers with skin panel plies, allowing for precise location and shaping of stiffeners directly on the fiber placement tool, using thermoplastic materials that conform to compound contours, and incorporating filler plies within the skin panel structure to provide pressure transfer and indexing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If pre-formed composite fillers are used to fill the radius gap, then the gap can be filled, but the handling and positioning becomes labor-intensive and time-consuming

Engineering Contradiction:
Improveease of filler installationVSAvoidinstallation time
Core Design Contradiction:
Ease of manufactureVSLoss of time

Solution Approach 1:

The patent combines the filler and stiffener into a single integrated component called a 'pre-consolidated radius filler'. This merged component eliminates the need for separate handling and positioning of filler pieces, allowing the entire radius gap filling operation to be performed as one unit, thereby reducing labor intensity and installation time

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The filler is pre-consolidated and pre-shaped into the final configuration before installation. The radius filler is manufactured in advance with the correct geometry and material consolidation, so that during assembly no additional shaping, positioning, or splicing operations are required - the filler is ready for immediate installation in its final form

Inventive Principle:
Principle #10Preliminary action

2Quantity of substance

If thermoplastic materials are used for fillers, then material availability is improved, but the rigidness makes them hard to conform to compound contours

Engineering Contradiction:
Improvematerial availabilityVSAvoidconformability to contours
Core Design Contradiction:
Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent applies heat to the thermoplastic radius filler during installation, temporarily changing its physical state from rigid to pliable. This parameter change allows the filler to be conform ed to the compound contours of the radius gap. Once cooled, the filler returns to its rigid state, maintaining structural integrity while having already achieved the desired shape

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If additional tooling and templates are used for precise positioning, then positional accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvepositional accuracy of stiffenerVSAvoidtooling complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The pre-consolidated radius filler is designed with self-positioning features that allow it to automatically locate and align itself within the radius gap without requiring external templates or specialized tooling. The filler's geometry and consolidation characteristics enable it to self-align during installation, achieving precise positioning through its own structural properties rather than through additional positioning devices

Inventive Principle:
Principle #25Self-service

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 reduces handling time, improves positional accuracy, and enhances the assembly process by enabling precise placement and integration of stiffeners without additional tooling, while also reducing the likelihood of cracks and material weight.

Implementation Method 1

heating the initial radius filler to at least one of a cure temperature, a melting temperature, or a fusing temperature to form, from the initial radius filler, a radius gap filler in the radius gap

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

heating the initial radius filler to at least one of a cure temperature, a melting temperature, or a fusing temperature

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

heating the initial radius filler to at least one of a cure temperature, a melting temperature, or a fusing temperature

Methodology Applied
Scientific EffectCuring: Photopolymerisation

Implementation Method 4

compressing the composite panel and the composite stiffening member together via consolidation pressure

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP4431268B1Composite parts, and methods of manufacturing
Publication Date: 2025.12.31 SPIRIT AEROSYSTEMS INC
  • EP4431268B1 patent drawingFigure 1
  • EP4431268B1 patent drawingFigure 2
  • EP4431268B1 patent drawingFigure 3

AI summary

A method for manufacturing a composite part includes forming an initial radius filler on a composite panel. The initial radius filler is formed from a plurality of plies of composite material stacked on the composite panel. The method includes forming a radius of curvature on at least one side of the initial radius filler, positioning a composite stiffener on the composite panel, wherein the composite stiffener is contoured to define a radius gap when joined with the composite panel, positioning the composite stiffener against the at least one side of the initial radius filler, compressing the composite stiffener, composite panel, and initial radius filler via vacuum bag, and heating the initial radius filler to at least one of a cure temperature, a melting temperature, or a fusing temperature to form, from the initial radius filler, a radius gap filler in the radius gap.