Y-Shaped Composite Stringer Design for Buckling Resistance
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Solution Overview
Problem
Existing stringers and spars in the aerospace industry, particularly those with 'double T' and 'omega' sections, suffer from limited momentum of inertia, buckling, post-buckling, and torsional issues, while also requiring improvements in weight savings and cost efficiency.
Innovation Solution
The development of a Y-shaped composite material stringer and a double Y-shaped cross-section spar, which enhance structural efficiency, reduce manufacturing wrinkles, and improve Non-Destructive Testing (NDT) processes. These components are manufactured using specific molding techniques and composite materials, such as carbon fiber or glass fiber with thermoset or thermoplastic resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional 'double T' or 'omega' section stringers are used, then manufacturing is simpler, but momentum of inertia is limited and buckling resistance is poor
Solution Approach 1:
The patent applies asymmetry by transitioning from symmetric 'double T' or 'omega' sections to an asymmetric Y-shaped cross-section. The Y-shape features a vertical web with two diagonal flanges forming approximately 120-degree angles, creating an asymmetric geometry that optimizes the distribution of material to increase the moment of inertia while maintaining manufacturability through controlled mold opening angles.
2Reliability
If conventional 'double T' or 'omega' section spars are used, then manufacturing is easier, but torsional behavior and buckling resistance are insufficient
Solution Approach 1:
The patent applies parameter changes by optimizing the geometric parameters of the Y-shaped cross-section, specifically the flange angles (approximately 120 degrees) and the web thickness distribution. These parameter optimizations enhance the structural performance against buckling and torsional loads while keeping the molding process feasible by controlling the curvature angles within manufacturable ranges.
3Strength
If Y-shaped stringers with high angle joints are manufactured, then structural efficiency improves, but manufacturing wrinkles may occur
Solution Approach 1:
The patent applies curvature principles by designing the Y-shaped stringer with optimized transition zones between the web and flanges. The joints are rounded with controlled radii rather than sharp corners, which distributes stress concentrations and prevents wrinkle formation during composite curing while maintaining the structural efficiency of the high-angle configuration.
4Weight of moving object
If conventional spars are used in torsion boxes, then manufacturing is simpler, but weight savings and cost efficiency are reduced
Solution Approach 1:
The patent applies composite materials by manufacturing the Y-shaped spars from carbon fiber or glass fiber reinforced polymers. This enables significant weight reduction compared to conventional metallic spars while maintaining or enhancing structural performance. The composite construction allows for optimized fiber orientation along the load paths of the Y-shape, maximizing strength-to-weight ratio.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The Y-shaped stringer and double Y-shaped spar demonstrate improved structural efficiency, increased momentum of inertia, enhanced buckling and torsional behavior, and offer weight and cost savings, making them more efficient than conventional designs.
Implementation Method 1
curing the Y-shaped preform with an autoclave cycle to obtain the Y-shaped stringer
Data Source
AI summary
A method for manufacturing a Y-shaped stringer (100) made of composite material, the Y-shaped stringer (100) includes a stringer web (110) having a cross-section in a I-shape, lower flanges (130a, 130b), a first opened triangular-shaped cross-section structure (120) comprising first and second lower vertices (120a, 120b) respectively joined to the lower flanges (130a, 130b) and an upper vertex (120c) connected to a first end of the stringer web (110), wherein the first opened triangular-shaped cross-section structure (120) and the stringer web (110) form a cross-section in a Y-shape.