Aircraft Hat Stiffener With Canted Webs
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Solution Overview
Problem
Existing hat stiffener designs in aircraft structures face limitations in weight efficiency and stability due to web instability, particularly when attempting to increase bending stiffness, as taller webs are prone to buckling, and methods to enhance thickness or cap angle lead to increased weight or compromised shear resistance.
Innovation Solution
A hat stiffener with non-linear webs featuring canted portions, which are formed during manufacturing using a hat tool with a substantially hat-shaped cross-section configuration, allowing for increased stability and buckling resistance without significant weight increase, by altering the cant angle and number of canted sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the height of the webs of the hat stiffener is increased to achieve greater bending stiffness, then the bending efficiency is improved, but the webs become more prone to instability and buckling
Solution Approach 1:
The web of the hat stiffener is configured with a curved geometry instead of a straight configuration. The curvature provides geometric stiffness that resists buckling while allowing the web to maintain a taller height for improved bending efficiency. The curved shape distributes stresses more effectively along the web length.
Solution Approach 2:
The patent modifies the geometric parameters of the web by introducing a curvature radius and adjusting the web thickness distribution along the curved path. These parameter changes optimize the web's resistance to buckling while maintaining the desired bending stiffness through increased height.
2Stability of the object's composition
If the thickness of the entire hat stiffener or the webs is increased to generate buckling or crippling resistance, then the stability margin is improved, but the overall weight of the stiffened panel structure increases
Solution Approach 1:
Instead of uniformly increasing the thickness of the entire hat stiffener, the patent applies increased thickness locally at the web where buckling resistance is most needed. The cap and flanges maintain their original thickness, optimizing weight while providing targeted stability enhancement where the curved web geometry provides maximum benefit.
Solution Approach 2:
The curved web geometry inherently provides increased buckling resistance without requiring proportional increases in material thickness. The curvature creates a more efficient load path that resists compressive forces, allowing for weight reduction compared to straight-web configurations with equivalent stability.
3Length of moving object
If the cap angle is decreased to increase the steepness of the web and decrease the length of the web, then the web length is reduced, but the shear path between the cap and skin panel structure is compromised
Solution Approach 1:
The curved web configuration allows for an optimized cap angle that maintains adequate shear path length while reducing the overall web length. The curvature compensates for the reduced length by providing geometric stiffness and improving the load transfer path between the cap and skin panel structure.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A hat stiffener (50) with canted web portions(52a and 52b) and a method of producing the same are disclosed. The hat stiffener has a cap (56). The hat stiffener further has a first web (52a) and a second web (52b) extending from opposite ends of the cap. The first web and the second web are non-linear and include at least one canted portion (64). The hat stiffener further has a first flange (84a) extending outwardly from a first web base portion and a second flange (84b) extending outwardly from a second web base portion.