Helicopter Rotor Blade Composite Skin Design

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Solution Overview

Problem

Conventional helicopter rotor blades face manufacturing challenges due to cumulative tolerances and defects caused by interference of components during assembly, with the internal torque tube providing most structural strength while the skins offer little stiffness.

Innovation Solution

A rotor blade design featuring a structural composite skin with fiber-reinforced epoxy material, a composite spar, and a foam core, which provides significant structural stiffness and mechanical strength, along with a method using automated fiber placement and adhesive bonding to improve manufacturability and reduce defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional separate component fabrication and assembly is used, then manufacturing flexibility is maintained, but cumulative tolerances cause assembly defects and mold closure problems

Engineering Contradiction:

Improveassembly precisionVSAvoidassembly complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges multiple separate components (skins, spar, core) into a single integrated composite structure manufactured as one piece using automated fiber placement. This eliminates the need for separate assembly operations, thereby eliminating cumulative tolerance problems and assembly defects while maintaining manufacturing flexibility.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent segments the manufacturing process into automated fiber placement layers that are built up sequentially to form the complete blade structure. This allows precise control of each layer's placement and properties, achieving high assembly precision through controlled material deposition rather than mechanical assembly of pre-fabricated parts.

Inventive Principle:

Principle #1Segmentation

2Strength

If rigid D-spar is used for structural strength, then mechanical strength is provided, but cumulative tolerances prevent mold closure and cause defects

Engineering Contradiction:

Improvestructural strengthVSAvoidassembly tolerance

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent changes the physical state and properties of the structural material from rigid pre-fabricated D-spar to flexible fiber-reinforced composite layers that are placed and then cured. During the placement stage, the material can accommodate tolerance variations; after curing, it achieves the required structural strength.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses fiber-reinforced composite materials that combine the strength of rigid structures with the manufacturing flexibility of flexible layup. The composite structure achieves D-spar-level strength while allowing for tolerance compensation during the automated fiber placement process, eliminating mold closure problems.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If skins serve only as fairings with little structural stiffness, then manufacturing is simplified, but structural stiffness and mechanical strength are insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidstructural stiffness

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent makes the skins multi-functional by designing them to provide both aerodynamic fairing and primary structural stiffness. The same skin layers that form the aerodynamic surface also serve as load-bearing structural elements, eliminating the need for separate structural reinforcement while maintaining manufacturing simplicity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses fiber-reinforced composite materials for the skins that provide both aerodynamic smoothness and high structural stiffness. The fiber orientation and material selection enable the skins to carry structural loads while maintaining their fairing function, achieving dual functionality without complicating the manufacturing process.

Inventive Principle:

Principle #40Composite materials

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 new design enhances manufacturability, reduces defects, and provides a rotor blade with improved structural stiffness and mechanical strength, making it easier and more cost-effective to produce.

Implementation Method 1

Methodology Applied

Scientific EffectComposite materials: Composite Materials

Implementation Method 2

a method using automated fiber placement and adhesive bonding to improve manufacturability and reduce defects

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentUS8632310B2Rotor blade and method of making same

Publication Date: 2014.01.21 TEXTRON INNOVATIONS INC

AI summary

A helicopter rotor blade includes a structural composite skin defining a cavity therein; a composite spar disposed within the cavity and adhesively bonded to the skin, a portion of the spar exhibiting a C-shape in cross section; and a foam core disposed within the cavity and adhesively bonded to the skin. The structural composite skin forms an external, closed box structure configured to transmit mechanical loads encountered by the rotor blade.