Embedded Spar Tab for Composite Airfoil Attachment
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Solution Overview
Problem
Existing methods for attaching composite airfoils to metallic components in gas turbine engines face challenges due to dislodging forces and moments, leading to reduced durability and lifespan of both the airfoils and fan frame assemblies.
Innovation Solution
A composite article design featuring a spar with an embedded tab that includes indented or recessed surfaces and hooking means, allowing the composite airfoil to be securely mounted on a metallic shank, resisting dislodging forces and moments through mechanical locking and contact with the tab's edges and surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If simple adhesive bonds are used to attach composite airfoils to metallic mounts, then the attachment process is simple, but the bonds are subject to dislodging forces and moments that reduce reliability and lifespan
Solution Approach 1:
The patent replaces the chemical adhesive bonding system with a mechanical attachment system. The composite airfoil incorporates a metallic spar with a tab that fits into a recess in the metallic mount, creating a mechanical interlock that resists dislodging forces and moments without relying on adhesive bonds.
Solution Approach 2:
The patent uses a hybrid composite-metalllic structure where a metallic spar is embedded within the composite airfoil. This composite construction combines the weight reduction benefits of composite materials with the strength and rigidity of metal, allowing the airfoil to withstand the forces and moments experienced during operation while maintaining a reliable mechanical attachment.
2Weight of moving object
If composite airfoils are made lighter to reduce engine weight, then weight reduction is achieved, but the attachment to metallic mounts becomes more challenging due to limited component size and magnitude of loads
Solution Approach 1:
The patent merges the attachment function directly into the composite airfoil structure by embedding a metallic spar within the composite material. This integration eliminates the need for separate attachment hardware and simplifies the overall assembly, reducing device complexity while maintaining the weight benefits of composite construction.
Solution Approach 2:
The patent transitions from a two-dimensional surface attachment (adhesive bonds on the airfoil surface) to a three-dimensional embedded attachment (metallic spar embedded within the composite structure). This dimensional change allows the attachment to distribute loads throughout the volume of the composite airfoil, reducing stress concentrations and simplifying the attachment design.
Data Source
AI summary
A composite article including composite component extending heightwise from a component base to a component tip and lengthwise between spaced apart component first and second edges. Component plies having widthwise spaced apart ply first and second sides and ply edges therebetween. Component mounted on a spar which includes a shank extending heightwise into the composite component, tab at upper end of shank and substantially or fully embedded in the composite component, and tab tip. Ply edges of at least a first portion of the plies directly or indirectly contacting or pressing against the tab. Ply edges of at least a second portion of the plies may directly or indirectly contact or press against the tab tip. Ply edges of first portion may press against one or more indented or recessed surfaces in the tab. The composite article may be a composite blade or vane including a composite airfoil.