Composite Vane Root Fastening for Unducted Fan Engines
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Solution Overview
Problem
The design of vanes for unducted fan engines faces challenges in balancing optimal aerodynamic performance, mechanical resistance, and minimal mass, particularly under intense aerodynamic forces and vibrational excitations, which can damage composite materials when used with pinned fasteners.
Innovation Solution
A vane comprising a composite material structure with a fiber reinforcement obtained by three-dimensional weaving, featuring a blade part and a vane root part connected via a fastening mechanism that includes a cavity, shoulder, and locking part, embedded in a matrix, which allows for variable pitch and resistance to aerodynamic forces while minimizing mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If vanes are made of composite material to reduce mass, then mass is reduced, but the vanes become susceptible to damage from intense aerodynamic forces and vibrational excitations
Solution Approach 1:
The vane is constructed using composite materials consisting of fiber reinforcement (obtained by three-dimensional weaving) embedded in a matrix. This composite structure provides both the mass reduction benefits of lightweight materials and the structural strength needed to withstand intense aerodynamic forces and vibrational excitations, resolving the contradiction between mass reduction and reliability.
Solution Approach 2:
The fiber reinforcement is obtained by three-dimensional weaving, creating a non-uniform local structure where fiber density and orientation vary throughout the vane. This allows different regions of the vane to have optimized properties for their specific functional requirements - the blade part for aerodynamic performance and the vane root part for structural connection, thereby improving overall reliability while maintaining low mass.
2Productivity
If vane span is increased to improve aerodynamic performance and bypass ratio, then aerodynamic efficiency improves, but the vanes experience more intense aerodynamic forces and higher vibrational excitation
Solution Approach 1:
The composite material structure with three-dimensionally woven fiber reinforcement provides high strength-to-weight ratio, enabling the vane to have large span for improved aerodynamic performance while the composite structure itself withstands the more intense aerodynamic forces and bending forces that result from the increased span.
Solution Approach 2:
The three-dimensional weaving of fiber reinforcement creates a complex internal structure with optimized fiber orientation and density distributions. This parameter change in the material structure allows the vane to achieve optimal aerodynamic performance through increased span while the internal fiber architecture provides the necessary strength to resist the corresponding increase in aerodynamic and bending forces.
3Ease of manufacture
If pinned fasteners are used to connect vanes to hub, then ease of assembly is improved, but vibrational excitations on 1N, 2N and 3N engine orders cause damage
Solution Approach 1:
The composite material structure of the vane root part provides inherent vibration damping and stress distribution capabilities. When combined with the fastening mechanism, the composite structure reduces the transmission of vibrational excitations to the pinned fasteners, thereby reducing vibrational damage while maintaining the ease of assembly benefits of pinned connections.
Solution Approach 2:
The vane root part made of composite material acts as an intermediary between the blade part and the pinned fasteners. This intermediate composite structure absorbs and distributes vibrational stresses, protecting the pinned fasteners from direct exposure to high-vibration excitations while still allowing for easy assembly through the pinned connection mechanism.
Data Source
AI summary
The present invention relates to a blade (7) comprising: —a composite material structure (17), —a blade root fastening portion (9) further comprising a shoulder (10) extending into the recess from the wall —a base (18) arranged in the recess and comprising a support member configured to abut against the shoulder (10) of the blade root fastening portion (9) and a passage (39) formed in the support member, the sections (23) of the blade root portion (22) of the composite material structure extending through the passage (39), and —a blocking part (19) arranged in the recess between the two sections (23) of the blade root portion (22) such that each section of the blade root portion (23) is pressed against the support member by the blocking part (19).