Segmented Bonded Joint Structure for Rotorcraft Crack Arrest
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Solution Overview
Problem
Existing structurally bonded arrangements in rotorcrafts face challenges in demonstrating damage tolerance and crack propagation, with cracks often going undetected due to limited accessibility and inspection methods, leading to potential structural failure.
Innovation Solution
A structurally bonded arrangement that subdivides the bond line into multiple independent sub-bondings using intermeshing patterns and separate interconnecting components, which act as crack-stoppers, reducing critical peel stresses and enhancing load transfer capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate crack-stopping features (additional rivets) are introduced in bond lines, then crack growth is stopped and damage tolerance is improved, but device complexity and manufacturing complexity increase
Solution Approach 1:
The bond line is segmented into multiple independent sub-bondings by introducing spacing elements that create interruptions. This segmentation naturally divides the continuous bond line into discrete segments, providing inherent crack-stopping features without requiring additional rivets or complex crack-arrest mechanisms. The spacing elements themselves create the segmentation that prevents crack propagation across the entire bond line length.
Solution Approach 2:
The spacing elements serve dual functions: they provide structural support for the adhesive bonding while simultaneously acting as crack-stopping features. By merging the support function and crack-arrest function into a single integrated element, the design avoids adding separate crack-stopping features, thereby reducing device complexity while maintaining damage tolerance.
2Measurement precision
If inspection methods are applied to bonded joints, then defect detection capability is improved, but accessibility limitations and inspection quality remain problematic
Solution Approach 1:
By segmenting the bond line into multiple independent sub-bondings with spacing elements, the inspection scope is divided into smaller, more accessible segments. Inspectors can focus on individual sub-bondings rather than attempting to inspect an entire continuous bond line, improving accessibility and inspection quality. The spacing elements create natural inspection points and reduce the complexity of detecting defects in each segment.
3Strength
If a continuous bond line is used, then load transfer capability is maximized, but crack propagation risk increases and damage tolerance decreases
Solution Approach 1:
The continuous bond line is divided into multiple independent sub-bondings separated by spacing elements. This segmentation prevents crack propagation across the entire bond line length, as cracks are confined to individual sub-bondings. The spacing elements act as physical barriers that stop crack growth, thereby improving damage tolerance while maintaining overall load transfer capability through the distributed arrangement of multiple sub-bondings.
Solution Approach 2:
The spacing elements are strategically positioned at critical locations where crack initiation and propagation are most likely to occur. By concentrating crack-arresting functionality at these specific locations rather than uniformly throughout the entire bond line, the design maintains high load transfer capability in the bonded regions while providing targeted damage tolerance where it is most needed.
4Reliability
If multiple separate interconnecting components are used instead of a single component, then crack-stopping features are inherent and damage tolerance is improved, but manufacturing complexity increases
Solution Approach 1:
The single interconnecting component is divided into multiple separate interconnecting components that are distributed along the bond line. Each component forms a独立的 sub-bonding with the adjacent surfaces. This segmentation inherently provides crack-stopping features, as cracks cannot propagate between separate components. The modular nature of multiple separate components also simplifies manufacturing and assembly compared to creating a single large complex component.
Solution Approach 2:
The multiple separate interconnecting components automatically provide crack-stopping functionality through their distributed arrangement and the natural gaps between them. The spacing elements and component arrangement self-generate the crack-arresting effect without requiring additional features, modifications, or separate crack-stopping mechanisms, thereby simplifying the overall manufacturing process.
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
The present technology is related to a structurally bonded arrangement (160) for structurally bonding a first component (210) to a second component (220). The structurally bonded arrangement includes a first connecting area (215) of the first component (210), a second connecting area (225) of the second component (220) that is spaced apart from the first connecting area (215) to form an interspace (230), and multiple interconnecting components (270) arranged across the interspace (230). First and second interconnecting components (270a, 270b) of the multiple interconnecting components (270) are structurally bonded separate from each other to the first connecting area (215) at separate first bonding areas (280a, 280b) and to the second connecting area (225) at separate second bonding areas (290a, 290b) thereby structurally bonding the first component (210) to the second component (220). The present technology is also related to a rotorcraft (100) with such a structurally bonded arrangement (160).