Aircraft Composite Fitting Delamination Prevention
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Solution Overview
Problem
Carbon fiber T-shaped fittings for aircraft horizontal lifting surfaces experience delamination issues in the rowing area and at the interface between structural angles and external plates, failing to meet stress and design requirements similar to traditional titanium fittings.
Innovation Solution
A carbon fiber fitting design comprising two angled pieces, an external plate, and a skin, where the skin is independent of the angled pieces, with a central rib and optional shimming, and a roving area filled with fibers or sealant, ensuring no ply continuity and rivet-free angles, which addresses delamination by redistributing load and eliminating delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a carbon fiber T-shaped fitting is made with two structural angles and a structural external plate joined together, then the weight is reduced compared to titanium fittings, but delamination occurs in the rowing area and at the interface between structural angles and external plate
Solution Approach 1:
The fitting is divided into three independent components: two angled pieces and an external plate, where the skin is independent from the angled pieces. This segmentation eliminates the delamination-prone continuous ply structures while maintaining structural integrity through discrete, well-defined interfaces.
Solution Approach 2:
A rowing filled with fibers or sealant is introduced as an intermediary element between the angled pieces and external plate. This rowing acts as a bonding medium that prevents delamination at the interfaces while allowing the carbon fiber components to remain structurally independent.
2Ease of manufacture
If carbon fiber fittings use traditional joined structures with continuous plies, then manufacturing is simplified, but delamination occurs under stress conditions
Solution Approach 1:
The manufacturing process is simplified by creating three separate components (angled pieces and external plate) that are manufactured independently and then assembled. This avoids the complexity of creating continuous ply structures that are prone to delamination, while maintaining ease of manufacture through modular assembly.
Solution Approach 2:
The skin is made independent from the angled pieces at critical interfaces where delamination occurs. This local modification in the structure's quality—creating discrete interfaces rather than continuous plies—prevents delamination while maintaining overall manufacturing simplicity.
3Strength
If the skin is joined to the angled pieces with rivets or continuous plies, then structural strength is maintained, but delamination occurs in the rowing area
Solution Approach 1:
The skin is extracted from the angled pieces, making it an independent component. This removal of the direct join between skin and angled pieces eliminates the delamination-prone continuous ply structure, while structural strength is maintained through the rowing filled with fibers or sealant.
Solution Approach 2:
The rowing filled with fibers or sealant serves as an intermediary bonding element between the skin and angled pieces. This intermediary structure provides the necessary structural strength while preventing delamination by creating a controlled interface rather than a direct continuous ply connection.
Data Source
Figure 1~2
AI summary
Fitting for aircrafts, comprising two angled pieces (1) joined to each other, each of them defining a first section (11) and a second section (12), an external plate (2) joined with both angled pieces (1), and a skin (3) joined to the external plate (2), the skin (3) being independent from the angled pieces (1). It permits to discharge the radius of the fitting angles defined by the angled pieces, discharging both angles, assuring than there is no rivet or similar joining elements installed in the angled pieces, assuring no ply continuity in the marked area.