Integrally Stiffened Panel Inverted Pocket Joint Buckling
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Solution Overview
Problem
Conventional integrally stiffened panels are susceptible to buckling deformation at the intersections of stiffeners, requiring additional structural reinforcement like edge doublers, which increases weight and compromises efficiency.
Innovation Solution
The integration of bead stiffeners with inverted pocket geometry at joints provides moment and stiffness continuity across intersections, enhancing load-carrying capacity and structural efficiency by maintaining area moment of inertia and offering multiple load paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional beads are used in stiffened panels, then the panel can be manufactured with simple geometry, but the panel is susceptible to buckling deformation at stiffener intersections requiring additional structural reinforcement
Solution Approach 1:
The patent applies local quality by modifying the geometry specifically at the stiffener intersection regions. The inverted pocket geometry is localized at joint areas where stiffeners intersect, while the rest of the panel maintains conventional simple geometry. This targeted geometric modification provides enhanced moment and stiffness continuity precisely where needed (at intersections) without complicating the overall panel structure.
Solution Approach 2:
The patent employs inversion by using inverted pocket geometry at the stiffener intersections. Instead of the conventional protruding bead geometry, the pockets are inverted (concave rather than convex) to create complementary geometric profiles that interlock at joint regions. This inverted configuration enables moment continuity and stiffness transfer across stiffener intersections, preventing buckling deformation without requiring additional structural reinforcement.
2Strength
If edge doublers or structural reinforcement are added to prevent buckling, then buckling resistance is improved, but the weight of the panel increases
Solution Approach 1:
The inverted pocket geometry is localized specifically at the stiffener intersection regions where buckling resistance is needed, rather than adding weight throughout the entire panel. This targeted approach provides enhanced buckling resistance at critical joints while maintaining lightweight construction in the rest of the panel structure.
Solution Approach 2:
The patent changes the geometric parameters of the stiffener intersections by introducing inverted pocket geometry with specific dimensional relationships. The pocket depth, width, and positioning are optimized to provide adequate moment continuity and stiffness transfer, achieving buckling resistance through geometric parameter optimization rather than adding material weight.
3Ease of manufacture
If beads terminate prior to intersection with other beads, then manufacturing is simplified, but the panel becomes susceptible to buckling in the areas between beads and frame members
Solution Approach 1:
Instead of terminating beads before intersection (which simplifies manufacturing but creates weak zones), the patent inverts the geometry at the intersection regions to create interlocking pockets. This inverted configuration allows the stiffeners to effectively continue through the intersection zone, maintaining buckling resistance while still being manufacturable through conventional processes.
Solution Approach 2:
The patent merges the functions of multiple beads by creating an integrated inverted pocket geometry at the intersection that combines the stiffening functions of intersecting beads into a unified structural feature. This merging provides continuous buckling resistance across the intersection zone while simplifying the manufacturing process by eliminating the need for separate bead termination and additional reinforcement operations.
Data Source
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AI summary
The integrally stiffened panel (201) includes one or more stiffeners (203) oriented in one direction, and one or more stiffeners (205) oriented in a different direction. The stiffeners are integral with a sheet member (209) and intersect at a joint (207). The joint is configured to incorporate a pocket (225) at the stiffener intersections. The pocket geometry is inverse to the stiffener geometry, and thereby provides moment and stiffness continuity across the joint and between adjacent intersecting stiffeners.