Composite Fan Blade Spar With Metal Casings to Prevent Delamination
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Solution Overview
Problem
Existing fan blades in unfaired engines face challenges in achieving optimal aerodynamic performance, mechanical resistance, and acoustic signature while minimizing weight, particularly when made of composite materials, due to risks of shell delamination and sudden mechanical behavior changes.
Innovation Solution
A composite material blade design with a spar reinforced by metal shells, where the metal shells extend inside the cavity of the blade to transmit aerodynamic forces via bending, preventing shell separation and ensuring structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the blade is made of composite material to reduce weight, then the weight is reduced, but the resistance to mechanical stresses and risk of shell delamination deteriorates
Solution Approach 1:
The blade is constructed using composite materials consisting of a composite core and metal shells. The composite core provides weight reduction while the metal shells provide structural reinforcement and resistance to mechanical stresses, creating a hybrid structure that combines the advantages of both material types.
Solution Approach 2:
The blade structure is divided into distinct segments: a composite material core and separate metal shells. This segmentation allows each component to be optimized for its specific function - the composite core for weight reduction and the metal shells for structural strength - while they work together as an integrated system.
2Strength
If metal shells are used to reinforce the blade root, then the structural strength is improved, but the risk of shell delamination and sudden mechanical behavior changes increases
Solution Approach 1:
An adhesive layer is introduced as an intermediary between the composite core and metal shells. This adhesive layer serves as a bonding medium that securely attaches the metal shells to the composite core, preventing shell delamination and ensuring reliable force transmission while maintaining structural integrity.
Solution Approach 2:
The metal shells are merged with the composite core through adhesive bonding to form an integrated hybrid structure. This merging ensures that the metal shells and composite core work together as a unified system, distributing loads effectively and preventing delamination under operational stresses.
3Productivity
If the blade span is increased to maximize aerodynamic performance and bypass ratio, then the aerodynamic efficiency is improved, but the mechanical stresses and acoustic signature deteriorate
Solution Approach 1:
The blade utilizes composite materials with optimized fiber orientation and distribution to maximize aerodynamic efficiency while maintaining mechanical strength. The composite structure allows for tailored material properties that resist the increased stresses associated with larger blade spans.
Solution Approach 2:
The blade structure implements local quality optimization by concentrating metal shell reinforcement at critical stress locations such as the blade root and leading edge, while maintaining lighter composite construction in less stressed areas. This localized approach maximizes strength where needed without compromising overall aerodynamic efficiency.
Data Source
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Figure 3A
AI summary
The invention relates to a blade comprising: - a blade body (12) having an aerodynamic profile comprising a first fibrous reinforcement obtained by three-dimensional weaving and comprising a first matrix in which the first fibrous reinforcement is embedded, the blade body part (12) comprising a cavity formed by a disconnection of the first fibrous reinforcement, - a blade root intended to be connected to a mechanism for the variable adjustment of the blade, and - a spar (13) comprising a core (14) made of composite material and two metal casings (21a, 21b) attached to the core (14) on either side of the core (14). The core (14) comprises a first part that extends inside the cavity of the blade body and a second part that forms the blade root. The two metal casings (21a, 21b) which are attached to the core (14) made of composite material extend over the second part and continue to extend over the first part inside the cavity of the blade body (12).