Composite Fan Blade Root Laminate Layout Against Delamination

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Solution Overview

Problem

The challenge is to reduce the weight of fan blades in turbofan engines while maintaining high resilience and prevent damage such as delamination due to foreign object collisions, particularly bird strikes, which generate excessive stress in the blade root.

Innovation Solution

A composite blade design with primary and secondary laminates alternately laminated in the blade thickness direction, featuring a specific arrangement of laminates to minimize stress concentration and prevent delamination, including a first area without laminate ends and a secondary laminate configuration that distributes stress effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the fan blade is made larger to increase bypass ratio, then fuel consumption rate is reduced, but the weight of the engine increases

Engineering Contradiction:

Improvefuel consumption rateVSAvoidweight of fan blade

Core Design Contradiction:

Use of energy by moving objectVSWeight of moving object

Solution Approach 1:

The fan blade is constructed using carbon fiber reinforced resin (CFRP) composite material, which provides high strength and resilience while significantly reducing weight compared to traditional metallic materials. This enables the use of larger fan blades for higher bypass ratios without proportionally increasing engine weight.

Inventive Principle:

Principle #40Composite materials

2Reliability

If foreign object collision occurs with the blade root, then local stress is generated, but damage such as delamination occurs when stress is excessively large

Engineering Contradiction:

Improveresilience against foreign object collisionVSAvoidstrength of blade root

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The blade root employs a specialized laminate structure with primary laminates extending to the airfoil section and secondary laminates extending to junctions of primary laminates. This local structural differentiation optimizes stress distribution specifically at the blade root where foreign object collisions occur, enhancing damage resistance without compromising overall blade strength.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The blade root laminate is segmented into primary laminates and secondary laminates with different extension patterns. Primary laminates continue from the blade surface to the airfoil section, while secondary laminates extend to junctions, creating a segmented structure that manages stress distribution and prevents delamination under collision loads.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12565843B2Composite blade

Publication Date: 2026.03.03 IHI CORP

AI summary

A composite blade includes: an airfoil section, a root (blade root), and primary laminates and secondary laminates alternately laminated at the root, which respectively include composite material layers. A side surface of the root includes a contactable surface contactable with a mounting groove. The primary laminates extend from the root to the airfoil section to be joined before reaching the airfoil section. The secondary laminates extend from the root to junctions of the primary laminates. The contactable surface has first and second edges. Inside the root, a first area located around the first edge and a second area located between the first area and the center plane of the root are set. End portions of the secondary laminates are not located in the first area. Parts of the primary and secondary laminates are alternately located along the blade thickness direction in at least a part of the second area.