Composite Stringer Edge Cutting Angle Optimization
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Solution Overview
Problem
The existing methods for manufacturing structural components in the aviation industry using composite materials with stiffening stringers often result in surface discontinuities and increased risk of moisture infiltration due to the 90° cut of stringer edges, leading to suboptimal load transfer and potential delamination.
Innovation Solution
The process involves cutting the stringer edges at a slanted angle instead of 90°, allowing for a smoother integration with the skin and the use of additional composite material layers or patch elements to seal and protect the edges, thereby reducing surface discontinuities and enhancing moisture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stringer edges are cut at 90° during manufacturing, then the manufacturing process is simple and efficient, but surface discontinuities occur and moisture infiltration risk increases
Solution Approach 1:
The patent applies preliminary action by pre-cutting the stringer edges at a slanted angle (e.g., 45°) before final assembly, rather than cutting at 90° during or after assembly. This preliminary preparation of the edge geometry enables smoother integration with the skin and reduces subsequent moisture infiltration risks, while maintaining manufacturing efficiency through a single-pass cutting operation.
2Ease of manufacture
If stringer edges are cut at 90°, then the cutting operation is straightforward, but load transfer between stringer and skin becomes suboptimal
Solution Approach 1:
The patent applies parameter changes by modifying the cutting angle parameter from the conventional 90° to a slanted angle (e.g., 45°). This parameter change optimizes the geometric compatibility between stringer and skin surfaces, thereby improving load transfer efficiency through better contact area and stress distribution, while the cutting operation remains straightforward.
3Reliability
If additional composite layers or patch elements are used to seal stringer edges, then moisture resistance and structural integrity improve, but manufacturing complexity increases
Solution Approach 1:
The patent applies the taking out principle by extracting the edge sealing function from the main stringer structure and implementing it through the slanted edge geometry itself. The slanted cut creates an inherent sealing profile that integrates with the skin, eliminating the need for separate patch elements or additional composite layers, thereby maintaining reliability while reducing manufacturing complexity.
Data Source
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AI summary
Process for manufacturing a structural component (1, 1', 1", 1''', 1"" ) made of composite material comprising a skin (2) and at least one stiffening stringer (3, 3', 3", 3"', 3"") applied rigidly and integrally to one face (2a) of the skin (2); the process comprises the following steps: a) arranging on a tool (12, 12', 12", 12''', 12"") a plurality of first layers (4; 4a', 4b'; 4"; 4'"'; 4a"", 4b"", 4c"") of uncured or p re-cured composite material forming the stringer (3, 3', 3", 3'", 3"") presenting a longitudinal axis (A) and having a raised portion (7, 7', 7", 7''', 7"" ) protruding from at least one flange (8) extending parallel to the longitudinal axis (A) and along a lying surface that is flat or is a surface of revolution (S);) b) arranging on said tool (12, 12', 12", 12''', 12"") a plurality of second layers of uncured or p re-cured composite material forming said skin (2); c) making a face (2a) of said skin (2), parallel to said lying surface (S), and said flange (8) of said stringer (3, 3', 3", 3'", 3"") adhere to each other; d) applying predetermined temperature and pressure on the assembly thus formed so as to compact said layers together, possibly curing the uncured material and rigidly joining said skin (2) to said stringer (3, 3', 3", 3'", 3"" ); and e) performing a cutting operation on the free end side edge/s (13) of said flange (8) in a transversal direction with respect to said lying surface (S); and f) cover said end side edge/s (13) of the end of said flange (8) with a coating of composite material so as to seal outwards the layers (4; 4a', 4b'; 4 "; 4'"; 4a"", 4b"") forming said flange (8).