Composite Propeller Blade Structure for Interlaminar Impact Strength
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Solution Overview
Problem
Propeller blades require high strength and low weight, particularly to withstand impacts such as bird strikes, while maintaining efficient manufacturing processes and design freedom.
Innovation Solution
A composite propeller blade design featuring a stack of plies with first yarns aligned in a direction and second yarns extending transverse to the plane of the ply, embedded in a matrix, which enhances interlaminar shear strength and damage tolerance, allowing for improved bonding with non-composite elements through textured surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite materials are used in propeller blades to reduce weight, then weight decreases, but interlaminar shear strength and bonding between layers deteriorate
Solution Approach 1:
The patent employs a multi-layer composite structure where each layer contains carbon fibre yarns embedded in a thermoplastic matrix. The key innovation is incorporating through-thickness yarns that penetrate multiple layers to mechanically bond them together, creating a hierarchical composite system that maintains low weight while significantly improving interlaminar shear strength through the combination of in-plane and through-thickness reinforcement.
Solution Approach 2:
The patent applies different yarn orientations and densities at different locations within the composite structure. Through-thickness yarns are strategically positioned at layer interfaces where bonding is most critical, while in-plane yarns provide structural strength within each layer. This localized optimization of material properties resolves the contradiction between weight reduction and interlaminar strength enhancement.
2Strength
If additional joining techniques are used to bond non-composite elements to composite blades, then bonding strength improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent integrates the bonding function directly into the composite blade structure itself through the thermoplastic matrix and through-thickness yarns. This eliminates the need for separate joining operations by merging the structural and bonding functions into a single integrated component, thereby reducing manufacturing complexity while maintaining bonding strength.
Solution Approach 2:
The thermoplastic matrix and through-thickness yarns provide self-bonding capabilities during the curing process. The material structure automatically bonds layers and attached elements together through thermal processing without requiring external joining operations, enabling the composite blade to serve its own joining needs.
3Productivity
If thermoplastic fibres are used to bond fabric layers, then manufacturing efficiency improves, but bonding strength at junctures may be insufficient without sufficient heat and pressure
Solution Approach 1:
The patent utilizes the thermoplastic matrix's phase transition properties, heating it above its melting point to enable flow and bonding, then cooling to solidify the bond. This parameter change approach allows efficient manufacturing through controlled thermal processing while ensuring adequate bonding strength at junctures where the thermoplastic material flows and interlocks with carbon fibre yarns.
Data Source
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AI summary
The present application provides a propeller blade comprising a composite member. The composite member comprises a stack of plies (102) and a matrix in which the stack of plies is embedded. At least one ply (102)comprises a plurality of first yarns (104) aligned in a first direction defining a plane of the ply (102) and a plurality of second yarns (106) extending transverse to the plane of the ply. (102) Each second yarn (106) does not extend through more than one ply (102). Also provided is a propelling system comprising the propeller blade, a composite propeller blade prepreg, and a method of forming a propeller blade.