Thermoplastic Composite Control Surface With Integrated Stiffeners

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Solution Overview

Problem

Existing aircraft control surfaces are prone to impact damage and require numerous components, which increases weight and reduces fuel efficiency.

Innovation Solution

A method for forming fiber-reinforced thermoplastic control surfaces by stacking composite sheets, overmolding stiffener structures, and welding skins together to create a monolithic structure with integrated sidewalls and hinges, optimizing material usage and reducing cycle time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional control surfaces are constructed with multiple separate components, then structural flexibility and ease of assembly are improved, but weight increases and fuel efficiency deteriorates

Engineering Contradiction:
Improveease of assemblyVSAvoidcontrol surface weight
Core Design Contradiction:
Ease of operationVSWeight of moving object

Solution Approach 1:

The patent merges multiple separate control surface components (skins, stiffeners, ribs, splice plates) into a single monolithic thermoplastic composite structure. This integration eliminates the need for numerous fasteners and joints, reducing overall weight while maintaining structural flexibility and ease of assembly through the unified design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs thermoplastic composite materials with fiber reinforcement to create a monolithic control surface structure. This composite material approach provides high strength-to-weight ratio, enabling weight reduction while maintaining structural integrity and flexibility needed for assembly and operation.

Inventive Principle:
Principle #40Composite materials

2Adaptability or versatility

If traditional control surfaces use numerous separate components, then manufacturing flexibility is improved, but component count increases and productivity deteriorates

Engineering Contradiction:
Improvemanufacturing flexibilityVSAvoidproduction efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent combines multiple manufacturing operations into a single molding process that produces the monolithic control surface structure in one piece. This eliminates sequential assembly steps for attaching skins, stiffeners, and ribs, significantly improving productivity while maintaining manufacturing flexibility through tooling design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent incorporates all structural features (stiffeners, ribs, splice plates) directly into the molding process before final assembly. This preliminary formation of all components in a single operation reduces subsequent assembly steps and improves overall production efficiency.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If control surfaces are made with integrated monolithic structure, then impact resistance is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveimpact resistanceVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses fiber-reinforced thermoplastic composite materials to create the monolithic structure, providing superior impact resistance through the composite's inherent toughness and fiber reinforcement. The thermoplastic matrix allows for energy absorption during impact while maintaining structural integrity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent utilizes the thermoplastic material's ability to change physical state with temperature, allowing the material to be molded at elevated temperatures and then cooled to achieve the final monolithic structure. This parameter change enables complex integrated geometries to be formed in a single process step.

Inventive Principle:
Principle #35Parameter changes

4Loss of substance

If thermoplastic composite sheets are stacked and compressed to form skins, then material utilization is improved, but manufacturing time increases

Engineering Contradiction:
Improvematerial utilization efficiencyVSAvoidmanufacturing cycle time
Core Design Contradiction:
Loss of substanceVSLoss of time

Solution Approach 1:

The patent merges the skin formation and stiffener integration steps into a single compression molding operation. Thermoplastic composite sheets are stacked with pre-formed stiffener structures between them, and the entire assembly is compressed and consolidated in one process, improving material utilization while reducing manufacturing time compared to separate operations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent exploits the thermoplastic material's phase transition between solid and molten states during compression molding. The material is heated to become more pliable for consolidation, then cooled to achieve the final rigid structure, enabling efficient material utilization and reduced cycle time through controlled thermal processing.

Inventive Principle:
Principle #36Phase transitions

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

The method enhances impact resistance, reduces component count, and improves fuel efficiency by minimizing weight and optimizing material usage.

Implementation Method 1

heating the overmolding tool

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

compressing, via the overmolding tool, the first skin and the second skin

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 3

injecting a fiber-reinforced thermoplastic material between the first skin and the second skin to form a stiffener structure

Methodology Applied
Scientific EffectInjection: Injector

Implementation Method 4

welding skins together to create a monolithic structure

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP3858584B1Thermoplastic composite panel systems and methods
Publication Date: 2026.04.01 ROHR INC
  • EP3858584B1 patent drawingFigure 1
  • EP3858584B1 patent drawingFigure 2A~2B
  • EP3858584B1 patent drawingFigure 2C

AI summary

A method for forming a fiber-reinforced thermoplastic control surface (600) includes forming first and second skins (610, 612) from a fiber-reinforced thermoplastic resin. The method further includes overmolding fiber-reinforced thermoplastic features onto the first skin (610) and/or second skin (612), including stiffener structures (614), sidewalls (633), and/or hinges. The method further comprises welding or consolidating the first and second skins (610, 612) together, along with the associated internal features overmolded thereon to form a single-piece, stiffened, fiber-reinforced thermoplastic control surface (600).