Composite Fan Blade Tip Wrap for Impact and Delamination Resistance
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Solution Overview
Problem
Composite fan blades fabricated using fabric or tape prepreg face issues with through-thickness impact capability and damage tolerance, leading to delamination at the tip and trailing edge, which can cause excess damage and limit fly-back thrust capability, and current metallic tip caps add significant weight and manufacturing costs.
Innovation Solution
A composite tip and trailing edge reinforcement wrap for composite fan blades, comprising a non-woven composite main body with a metallic sheath and a composite reinforcement wrap, which is attached to the main body outer surface and extends across the airfoil portion from the trailing edge to the leading edge, providing enhanced structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic tip caps are used to protect composite fan blades, then impact resistance and damage tolerance are improved, but weight and manufacturing cost increase significantly
Solution Approach 1:
The patent replaces traditional metallic tip caps with a composite material system consisting of a thermoplastic matrix and aramid fabric reinforcement. This composite construction provides the necessary impact resistance and damage tolerance while significantly reducing weight compared to metallic alternatives. The aramid fabric's high strength-to-weight ratio and the thermoplastic matrix's toughness create a protective structure that maintains blade integrity without the penalty of metal weight.
2Strength
If metallic tip caps are used to protect composite fan blades, then impact resistance and damage tolerance are improved, but manufacturing complexity and cost increase due to complex machining requirements
Solution Approach 1:
The patent changes the material state and processing parameters from metallic machining to composite fabrication. Instead of machining metal components, the solution uses a thermoplastic matrix that can be molded and formed directly into the required shape, then cured to create the protective cap. This eliminates complex machining operations and reduces manufacturing steps while maintaining the protective function.
Solution Approach 2:
The patent applies reinforcement selectively at the tip and trailing edge regions where impact damage is most likely to occur. The aramid fabric is positioned specifically in these high-stress areas, providing localized protection without requiring complex machining throughout the entire blade structure. This targeted approach simplifies manufacturing while maintaining damage tolerance where it is most needed.
3Weight of moving object
If conventional composite structures are used without additional reinforcement, then weight is minimized, but through-thickness impact capability and damage tolerance are insufficient
Solution Approach 1:
The patent incorporates the thermoplastic matrix and aramid fabric reinforcement as an integrated part of the blade manufacturing process, applying the protective layer during the initial fabrication stages. This preliminary action ensures that the reinforcement is properly bonded to the composite structure before the blade enters service, eliminating the need for separate post-manufacturing steps and ensuring consistent protection from the outset.
Solution Approach 2:
The patent uses a hybrid composite structure combining the original fiber-reinforced plastic blade material with an additional thermoplastic matrix and aramid fabric layer. This multi-material composite construction enhances through-thickness impact capability and damage tolerance while maintaining overall weight efficiency, as the reinforcement is optimized for specific protective functions rather than general structural support.
Data Source
AI summary
A composite tip and trailing edge reinforcement wrap for a composite fan blade including a non-woven composite main body forming an airfoil portion above a flow path and a tip adjacent the airfoil portion opposite a root portion; the airfoil portion defines a blade chord between a leading edge and a trailing edge, a concave pressure side and a convex suction side defined between the leading edge and the trailing edge, a blade span between the root portion and the tip; a metallic sheath attached to a main body outer surface proximate the leading edge; the composite tip and trailing edge reinforcement wrap attached to the main body outer surface located from the trailing edge and extends across the airfoil portion chordwise from the trailing edge to portions of the metallic sheath and extends spanwise from the tip along the airfoil portion to a predetermined distance of the blade span.