Composite Fan Blade Root With Segmented Cavity Blocking
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Solution Overview
Problem
Unducted fan blades face challenges in balancing optimal aerodynamic performance, mechanical strength, and reduced mass, particularly when made of composite materials, as they are susceptible to damage from intense aerodynamic forces and broadband vibratory loads.
Innovation Solution
A composite material blade structure with a fibrous reinforcement obtained by three-dimensional weaving, featuring a blade root fastening part with a cavity and blocking mechanism to prevent withdrawal and withstand vibratory loads, combined with a metal fastening part for enhanced rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If blades are made of composite material to reduce mass, then weight is reduced, but resistance to intense aerodynamic forces and broadband vibratory loads deteriorates
Solution Approach 1:
The blade root portion is divided into two separate sections (first and second sections) that are inserted into the cavity through different openings. This segmentation allows each section to be independently optimized and secured, improving the overall resistance to aerodynamic forces while maintaining the lightweight composite structure.
Solution Approach 2:
The two blade root sections are nested within the cavity of the fastening part, with each section inserted through its own opening. This nesting arrangement allows the composite blade sections to be housed within the metal fastening structure, combining the lightweight benefits of composites with the strength of metal fastening.
2Strength
If blades are made of metal material to ensure mechanical strength, then resistance to aerodynamic forces is improved, but mass increases
Solution Approach 1:
The invention merges two different materials (composite and metal) in a single blade structure. The blade portions are made of lightweight composite material, while the fastening part is made of metal to provide the necessary strength. This combination allows the blade to achieve both low mass and high strength resistance to aerodynamic forces.
Solution Approach 2:
The blade uses a composite structure combining composite material sections for the blade portions and metal material for the fastening part. This composite construction allows optimization of each part for its specific function: composites for lightweight aerodynamic surfaces and metal for high-strength fastening and load-bearing.
3Productivity
If blade span is increased to improve aerodynamic performance and by-pass ratio, then aerodynamic efficiency is improved, but resistance to broadband vibratory loads deteriorates
Solution Approach 1:
The blade root is segmented into two sections that can be independently positioned and secured within the cavity. This segmentation provides better distribution of vibratory loads across the fastening interface, improving reliability under broadband vibratory conditions while maintaining the large span required for aerodynamic efficiency.
Solution Approach 2:
The fastening part is designed with specific local features (cavity, multiple openings, blocking part) that concentrate strength and vibration resistance at the critical blade-root interface. This allows the majority of the blade span to be optimized for aerodynamics while the localized fastening structure handles the vibratory loads.
4Adaptability or versatility
If variable angle setting mechanism is added to adapt thrust to different flight phases, then adaptability is improved, but device complexity increases
Solution Approach 1:
The blade is segmented into distinct portions (aerodynamically profiled blade portion and blade root portion with two sections). This segmentation facilitates the integration of the variable angle setting mechanism by providing discrete components that can be independently positioned and secured, managing the complexity of the adjustable mechanism.
Data Source
AI summary
A blade is provided including a structure made of composite material including a fibrous reinforcement obtained by three-dimensional weaving and a matrix in which the fibrous reinforcement is embedded, the structure made of composite material including an aerodynamically profiled blade portion and a blade root portion, the blade root portion including two sections each connected to the blade portion, a blade root fastening part including a wall delimiting a cavity and an opening formed in the wall, the structure made of composite material extending through the opening so that the blade portion is located outside the fastening part and the blade root portion is located inside the cavity, and a blocking part disposed in the cavity, between the two sections of the blade root portion, in order to keep the two sections apart from each other so as to oppose withdrawal of the blade root portion from the cavity via the opening.