Composite Fan Blade Ply Drop Orientation for Bird Impact Resistance
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Solution Overview
Problem
Turbine blades made of composite materials face challenges in meeting mechanical and thermal stress requirements while maintaining aerodynamic performance and weight efficiency, particularly in withstanding bird and hail impacts, leading to complex design issues.
Innovation Solution
The blade design incorporates specific ply drop line configurations, including transverse and inclined terminal portions, to enhance mechanical resistance to impacts, with optimized ply drop lines on the pressure and suction sides, and a shield covering the composite structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the number of plies is reduced towards the blade head, leading edge and trailing edge to obtain decreasing thickness, then the weight is reduced and aerodynamic performance is improved, but the mechanical resistance to bird and hail impacts deteriorates
Solution Approach 1:
The patent applies local quality by varying the ply configuration specifically at the ply drop lines located in the lower region of the blade (between root and 70% blade height). The transverse portions of ply drop lines create localized reinforcement zones that provide enhanced impact resistance precisely where needed, while allowing the blade to maintain reduced thickness and weight in other regions.
Solution Approach 2:
The patent segments the blade structure by dividing it into different regions with different ply configurations. The lower region (0-70% blade height) contains optimized ply drop lines with transverse portions for impact resistance, while the upper region maintains standard progressive ply reduction for weight optimization. This segmentation allows simultaneous achievement of both weight reduction and impact resistance.
2Strength
If the blade thickness is increased to improve resistance to bird and hail impacts, then the mechanical strength is improved, but the aerodynamic performance deteriorates and design complexity increases
Solution Approach 1:
Instead of uniformly increasing blade thickness, the patent applies localized structural modifications only at specific ply drop line positions in the lower blade region. The transverse portions create targeted reinforcement zones that provide impact resistance without requiring overall thickness increase, thereby maintaining aerodynamic performance and reducing design complexity.
Solution Approach 2:
The patent incorporates preliminary reinforcement features during the manufacturing process by pre-positioning the transverse portions at ply drop lines. This preliminary action ensures impact resistance is built into the structure during fabrication, avoiding the need for complex post-manufacturing modifications or operational adjustments.
3Strength
If the ply drop lines are configured with transverse portions extending along transverse direction, then the mechanical behavior against impacts is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the geometric parameters of the transverse portions, specifying that they extend over at most 10% of the distance between leading and trailing edges. This parameter optimization balances the need for impact resistance with the practical constraints of manufacturing precision, ensuring that the transverse portions provide sufficient reinforcement without requiring excessively tight tolerances.
4Weight of moving object
If the number of plies is reduced to optimize weight, then the weight efficiency is improved, but the blade becomes more vulnerable to impact damage
Solution Approach 1:
The patent applies local quality by maintaining higher ply density specifically at the ply drop lines in the lower blade region where impact damage is most likely to occur, while allowing ply reduction in other regions for weight optimization. The transverse portions of ply drop lines create localized zones of enhanced reliability without compromising overall weight efficiency.
Data Source
AI summary
The disclosed fan blade is composed at least in part of a structure (50) made of composite material comprising a fiber reinforcement and a matrix. The fiber reinforcement includes a plurality of plies that are each formed of warp yarns and weft yarns. The warp yarns and weft yarns include incomplete yarns that each have a terminal end on the pressure side or the suction side (42). The pressure side and the suction side (42) each have at least one ply drop line (82, 83) connecting the terminal ends of the incomplete yarns of the same ply. At least one ply drop line (82) includes at least one transverse portion (90) extending generally along a transverse direction (T), including an apex portion (92). The at least one apex portion (92) extends over at most 10% of the distance between the leading edge (44) and the trailing edge (46).