Bonded Rotor Blade Cover with Rib Coupling for Shear Load Relief

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Solution Overview

Problem

Gas turbine engine rotor blades require strong, durable, and impact-resistant designs that improve engine performance, increase service life, and enhance operating efficiency, while being lightweight and cost-effective, but existing designs face challenges in managing shear loading and stress due to centrifugal effects, blade twist, and temperature cycling.

Innovation Solution

The rotor blade features a forging with internal cavities and ribs, an inner cover with coupling elements mechanically engaged with the ribs, and an outer cover bonded over the inner cover, providing increased coupling strength, reduced shear loading, and enhanced resistance to impact, stress, and fatigue through a combination of mechanical, frictional, and adhesive attachments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a rotor blade uses a solid forging design, then strength and durability are improved, but weight increases and manufacturing complexity increases

Engineering Contradiction:

Improveblade strengthVSAvoidblade weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The blade is segmented into a forging portion and a cover portion that encloses an internal cavity. This segmentation allows the blade to maintain strength through the forging while reducing weight by removing material from the interior, creating a hollow structure that preserves external load-bearing capabilities.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The blade combines different material structures by integrating a solid forging portion with a cover portion that may contain different material properties. This composite approach allows optimization of different regions for specific functions, such as strength in the forging and weight reduction in the cover.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If a rotor blade uses a hollow design with internal cavity, then weight is reduced, but structural strength and resistance to centrifugal effects deteriorate

Engineering Contradiction:

Improveblade weightVSAvoidblade strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the blade have different material distributions - the forging portion maintains solid construction for strength, while the cover portion creates a hollow structure for weight reduction. This local differentiation optimizes each region for its specific functional requirements.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If adhesive bonding is used to attach the cover, then manufacturing complexity is reduced, but resistance to shear loading and centrifugal forces deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidbond strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The bonding system merges multiple attachment mechanisms - adhesive bonding for basic attachment, mechanical interlocking features for structural strength, and frictional engagement for load distribution. This combination preserves the manufacturing simplicity of adhesive bonding while overcoming its weakness in shear resistance through the integrated mechanical features.

Inventive Principle:

Principle #5Merging (Combining)

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 solution results in a rotor blade that is more resistant to foreign object damage, stress, strain, and fatigue, offering increased durability and service life by distributing loads effectively and absorbing vibration energy, thus improving overall engine performance and efficiency.

Implementation Method 1

The coupling element extends along the internal cavity in cooperative engagement with the rib to reduce shear loading on the adhesive bond

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

The inner cover includes a coupling element extending along the internal cavity in cooperative engagement with the rib

Methodology Applied

Scientific EffectMechanical interlocking: Mechanical Fastener

Implementation Method 3

an inner cover bonded to the airfoil body over the internal cavity, and an outer cover bonded to the airfoil body over the inner cover

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Implementation Method 4

The rotor blade is more resistant to foreign object damage, stress, strain, and fatigue, offering increased durability and service life by distributing loads effectively and absorbing vibration energy

Methodology Applied

Scientific EffectVibration energy absorption: Damping

Data Source

PatentEP3964326A1Rotor blade with bonded cover

Publication Date: 2022.03.09 RTX CORP

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AI summary

An airfoil (10) comprises an airfoil body (12) with an internal cavity (16) and inner and outer covers (32,34). The airfoil body defines a first major surface of the airfoil, and a rib (18) extends along the internal cavity. The inner cover (32) is bonded to the airfoil body (12) over the internal cavity (16), and includes a coupling element (20) extending along the internal cavity in cooperative engagement with the rib. The outer cover (34) is bonded to the airfoil body (12) over the inner cover (32), and defines a second major surface of the airfoil.