Airfoil Cover Panel Locking With Rib Nodes and Plugs
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Solution Overview
Problem
Existing airfoils for gas turbine engines face challenges in achieving strong bonding between multiple pieces while minimizing weight, often requiring thick interfacial ribs that add weight and compromise structural integrity.
Innovation Solution
The airfoil design incorporates rib nodes with node cavities and a cover panel featuring tabs that are locked in place by plugs, providing a secure and lightweight attachment mechanism using a combination of metal and fiber-reinforced polymer composite materials, with the plugs and tabs designed to ensure structural integrity and aerodynamic smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive bonding is used to bond multiple airfoil pieces together, then manufacturing ease and weight reduction are improved, but bonding strength and structural integrity deteriorate due to insufficient surface area
Solution Approach 1:
The airfoil is divided into multiple discrete pieces (body and cover panel) that are joined through localized mechanical attachment points rather than requiring large bonded surfaces. The rib nodes are segmented into discrete cavities that receive individual plugs, creating multiple localized bonding points instead of relying on extensive adhesive surfaces.
Solution Approach 2:
The invention employs composite construction by combining metal rib nodes with polymer-based or fiber-reinforced polymer plugs. This material combination provides both the structural strength of metal and the weight reduction benefits of polymers, while the differential material properties enable effective mechanical interlocking through the tab-pinching mechanism.
2Strength
If thick interfacial ribs are used to provide structural strength, then bonding strength is improved, but weight increases undermining the weight reduction goal
Solution Approach 1:
Instead of using uniformly thick ribs throughout the airfoil structure, the invention concentrates structural reinforcement only at the critical rib node locations where pieces are joined. The node cavities provide localized structural strength precisely where needed for attachment, while the rest of the airfoil structure can be optimized for minimal weight.
Solution Approach 2:
The rib structure is segmented into discrete rib nodes with cavities rather than continuous thick ribs. This segmentation allows structural strength to be concentrated at specific attachment points while minimizing the overall volume and weight of rib material required throughout the airfoil structure.
3Strength
If multiple attachment points are used to secure cover panel, then bonding strength is improved, but device complexity increases
Solution Approach 1:
The invention merges multiple functions into the plug component: it serves as a mechanical anchor, a bonding element, and a structural connector simultaneously. The plug combines the attachment function with the structural reinforcement function, eliminating the need for separate fasteners and bonding materials, thereby simplifying the overall attachment mechanism despite using multiple attachment points.
Solution Approach 2:
The tabs on the cover panel automatically engage with the rib node cavities and are secured by the plugs through a self-locking pinching action. The structure itself provides the attachment mechanism without requiring external fasteners or complex assembly procedures, as the tabs and plugs work together to create a self-securing connection.
Data Source
Figure 1
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AI summary
An airfoil (58) includes a body (60) that has rib nodes (78) that each define a node cavity (80) therein. A cover panel (62) is carried on the body (60) over the rib nodes (78). The cover panel (62) includes tabs (62a) that project into the node cavities (80). Plugs (82) are disposed in the node cavities (80) and pinch the tabs (62a) against the node cavities (80) to lock the cover panel (62) on the body (60).