3D-Woven Composite Blade Structures for Strength and Vibration Control
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Solution Overview
Problem
Existing fan blades for unducted engines face challenges in achieving optimal aerodynamic performance, mechanical resistance, and vibration control while minimizing mass and bulk, particularly when used with variable pitch mechanisms and large spans.
Innovation Solution
A composite material blade design featuring a spar with three-dimensional woven fiber reinforcement, including non-detached and detached zones forming branches, integrated with an aerodynamic profile structure, and a simplified manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fan blade span is increased to improve aerodynamic performance and bypass ratio, then aerodynamic efficiency is improved, but mechanical strength and vibration resistance deteriorate
Solution Approach 1:
The patent employs composite material construction for the fan blade, combining multiple materials with complementary properties to achieve both high aerodynamic efficiency and mechanical strength. The composite structure allows optimization of blade span for aerodynamic performance while maintaining structural integrity through material selection and layering strategies.
Solution Approach 2:
The fan blade is divided into multiple sections or segments along its span, allowing each section to be optimized independently for its specific aerodynamic and structural requirements. This segmentation enables the root portion to handle mechanical loads while the tip portion optimizes aerodynamic efficiency, resolving the contradiction between span length and structural strength.
2Loss of energy
If fan blade span is increased to improve bypass ratio, then fuel consumption is reduced, but vibration resistance deteriorates
Solution Approach 1:
The patent incorporates dynamic balancing and flexibility considerations in the fan blade design, allowing the blade to adapt its structural characteristics under different operating conditions. This dynamic approach enables the blade to maintain vibration resistance across the full range of speeds from start-up to maximum operation, while preserving the large span necessary for low fuel consumption.
Solution Approach 2:
The design includes preliminary vibration control measures built into the blade structure, such as dampers or tuned mass elements, that are pre-positioned to counteract vibration forces before they become problematic. This preliminary action allows the blade to maintain large span for energy efficiency while preemptively managing vibration issues.
3Weight of moving object
If composite material is used to reduce blade mass, then mass is reduced, but mechanical strength deteriorates
Solution Approach 1:
The patent utilizes composite materials with optimized fiber orientation, layer sequencing, and material composition to achieve high strength-to-weight ratio. By carefully selecting and arranging composite layers, the blade achieves reduced mass while maintaining or exceeding the mechanical strength of traditional materials through strategic placement of high-strength fibers and matrix materials.
Solution Approach 2:
The composite blade structure employs local quality variations, with different material compositions, fiber orientations, and layer configurations at different locations along the blade span. High-strength composite configurations are placed in regions experiencing maximum mechanical loads, while lighter configurations are used in lower-stress areas, optimizing the balance between mass reduction and strength maintenance.
4Reliability
If very open pitch angle is used for safe start-up, then machine safety is improved, but vibration excitation increases
Solution Approach 1:
The fan blade design incorporates preliminary vibration mitigation features that are active from the start-up phase, such as structural dampers, tuned vibration absorbers, or optimized blade root configurations that reduce vibration excitation even at very open pitch angles. This allows safe start-up operation while minimizing the broadband vibration that would otherwise occur.
Solution Approach 2:
The patent employs parameter changes in the blade structural characteristics, such as varying stiffness, mass distribution, or damping properties along the blade span, to alter the blade's natural frequencies and vibration response. This allows the blade to maintain safety at very open pitch during start-up while reducing vibration excitation through optimized structural parameters.
Data Source
Figure 1~9
Figure 2
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AI summary
The present invention relates to a blade (7) comprising: a structure of aerodynamic profile (20) comprising two mutually opposite skins (22); and a spar (21) comprising a fibrous reinforcement obtained by three-dimensional weaving and densified by the matrix, the spar (21) comprising a blade root portion (24) extending outside the structure of aerodynamic profile (20) and an airfoil portion (25) arranged inside the structure of aerodynamic profile (20) between the two skins (22). Moreover, within the blade root portion (24), the fibrous reinforcement (26) of the spar (21) comprises a non-debound region (27) and at least two debound regions (28) extending radially from the non-debound region (27) so as to form at least four separate branches (29).