Undulating Edge Adhesive Joints for Aircraft Fuselage Fatigue
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Solution Overview
Problem
The mechanical durability and fatigue strength of adhesive connections between shell components in aircraft fuselages are compromised by peeling stress peaks at the peripheral edge regions, particularly due to pressure differences during flight.
Innovation Solution
The shell components are designed with undulating edges and inclinations in the overlapping regions, where the first shell portion has a crimped edge and the second shell portion tapers, reducing peeling stress by distributing force centrally within the adhesive layer and minimizing unfavorable loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If shell components are connected by adhesive bonding in overlapping portions, then the fuselage structure achieves smooth aerodynamic surfaces, but peeling stress peaks occur at peripheral edge regions reducing mechanical durability
Solution Approach 1:
The patent applies curvature to the edge of the first shell component, transforming it from a straight line to a curved profile that extends in an undulating manner in the longitudinal direction. This curvature redistributes the stress distribution along the adhesive bond line, preventing stress concentration at the peripheral edge regions while maintaining the overlapping configuration necessary for aerodynamic smoothness
2Force
If pressure differences occur during flight, then the fuselage experiences aerodynamic loading, but peeling stress peaks are introduced into the adhesive layer at edge regions
Solution Approach 1:
The curved edge profile of the first shell component modifies the stress distribution under aerodynamic loading. The undulating extension in the longitudinal direction creates a more gradual transition of forces along the adhesive bond line, reducing peeling stress peaks that would otherwise occur at sharp peripheral edges during pressurization and aerodynamic loading cycles
Solution Approach 2:
The patent changes the geometric parameter of the edge from a straight line to a curved profile with specific characteristics (extending in undulating manner in longitudinal direction). This parameter change alters the mechanical behavior of the adhesive connection under load, distributing peeling stresses more favorably and improving fatigue strength under repeated aerodynamic loading cycles
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
This design significantly enhances the mechanical durability and fatigue strength of the adhesive connection by reducing peeling stress and stress introduction into the adhesive layer, while also providing aerodynamic advantages through smooth transitions.
Implementation Method 1
a first outer face of the first shell portion and a second inner face of the second shell portion are adhesively bonded to each other by an adhesive layer
Data Source
AI summary
A shell arrangement for a fuselage of an aircraft includes a first shell portion extending in a curved manner in a shell peripheral direction and a second shell portion extending in a curved manner in the shell peripheral direction, wherein, in an overlapping portion of the shell arrangement, a first end region of the first shell portion and a second end region of the second shell portion overlap each other in the shell peripheral direction and a first outer face of the first shell portion and a second inner face of the second shell portion are adhesively bonded to each other by an adhesive layer, and wherein an edge of the first shell portion which terminates the first end region with respect to the shell peripheral direction extends in the overlapping portion in an undulating manner in a shell longitudinal direction which extends transversely relative to the shell peripheral direction.