Composite Blade Root Attachment with Metallic Reinforcement

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Non-ducted fan blades in aircraft engines face challenges in balancing optimal aerodynamic performance, mechanical resistance, and minimizing mass, particularly under intense aerodynamic forces and vibrations, which can damage composite materials when connected to the hub via pinned fasteners.

Innovation Solution

A composite material blade structure with a fibrous reinforcement obtained by three-dimensional weaving, featuring a blade part with an aerodynamic profile and a blade root part, a blade root attachment part with a cavity and blocking pieces, and a cover that compresses the blade root between the blocking parts and the shoulder, ensuring secure attachment and reduced mass.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If composite material is used to reduce blade mass, then weight is reduced, but the blade becomes vulnerable to damage from intense aerodynamic forces and vibrations

Engineering Contradiction:

Improveblade massVSAvoidblade resistance to aerodynamic forces

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The blade employs a composite material structure consisting of a fiber reinforcement obtained by three-dimensional weaving embedded in a matrix. This 3D woven composite provides both weight reduction and enhanced mechanical strength to withstand intense aerodynamic forces and vibrations during operation

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The attachment piece features a localized metallic reinforcement zone at the blade root area where it connects to the hub. This metallic insert provides enhanced strength and stiffness specifically at the critical interface zone, while the rest of the blade maintains its lightweight composite construction

Inventive Principle:

Principle #3Local quality

2Productivity

If blade span is increased to improve aerodynamic performance and bypass ratio, then aerodynamic efficiency is improved, but mechanical constraints and acoustic signature increase

Engineering Contradiction:

Improveaerodynamic efficiencyVSAvoidblade resistance to mechanical constraints

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The extended blade span is constructed using 3D woven composite materials that provide high strength-to-weight ratio, allowing the blade to maintain structural integrity and resist mechanical constraints over the increased span while preserving aerodynamic efficiency

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The blade incorporates a variable pitch mechanism that allows dynamic adjustment of the pitch angle during different flight phases. This enables the blade to adapt to varying aerodynamic conditions and mechanical constraints, optimizing performance across different operating regimes

Inventive Principle:

Principle #15Dynamics

3Reliability

If very open pitch is used for engine starting to ensure safety, then machine safety is improved, but broadband vibration excitation and bending forces increase

Engineering Contradiction:

Improvemachine safety during startingVSAvoidbroadband vibration excitation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The blade root attachment incorporates a metallic reinforcement insert and a structured attachment piece with locking pieces that provide enhanced strength and damping capacity. This pre-engineered reinforcement cushions the blade against the intense broadband vibrations and bending forces generated during engine starting with very open pitch

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The blade design allows for parameter changes in pitch angle during operation. During engine starting, a very open pitch is used for safety, and the reinforced attachment structure withstands the resulting vibrations. During normal operation, the pitch is narrowed to reduce vibrations while maintaining structural integrity

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP4117895B1Blade comprising a composite material structure and method of making the same

Publication Date: 2024.11.13 SAFRAN AIRCRAFT ENGINES SAS

Figure 1
Figure 2
Figure 3~4

AI summary

The present invention relates to a blade (7) comprising: - a structure (17) made of composite material; - a blade root attachment part (9) comprising a wall (25) delimiting a cavity (28), a first opening (29) formed in the wall (25) and a second opening (30) located under the blade root portion (22), the structure (17) made of composite material extending through the first opening (29); - two locking parts (19) configured to axially abut against a shoulder (10) of the attachment part (9) and to bear against the blade root portion (22); and - a cover (31) for compressing the blade root portion (22) against the locking parts (19).