Hybrid Metallic-Composite Joint With Integral Bearing Load Path
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Solution Overview
Problem
Aircraft retractable landing gear systems face challenges in efficiently transmitting structural loads between metallic and composite components, requiring an optimized load path to manage axial, compressive, and bending loads effectively while minimizing weight.
Innovation Solution
A metallic-composite joint fitting is developed, featuring a composite structure wrapped over an integral bearing with frustoconical portions and a sleeve, combined with a metallic end fitting having an externally threaded portion, optimized to distribute loads through threaded and non-threaded surfaces, ensuring efficient load transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite structures are used to reduce weight, then weight is reduced, but load transmission efficiency between metallic and composite components deteriorates
Solution Approach 1:
A metallic bearing is introduced as an intermediary component between the composite tube and metallic end fitting. The bearing provides a dedicated load-bearing interface that efficiently transmits axial, bending, and compressive loads from the composite structure to the metallic components, resolving the load transmission efficiency issue while maintaining the weight benefits of composite materials.
Solution Approach 2:
The solution employs a hybrid metallic-composite construction where a composite tube with flared ends interfaces with metallic components through a metallic bearing. This composite approach allows each material to be used where it performs best: composite for weight reduction and metallic for load-bearing interfaces, achieving both weight reduction and effective load transmission.
2Strength
If traditional metallic components are used for landing gear, then load bearing capability is sufficient, but weight increases
Solution Approach 1:
The landing gear component uses local quality by applying metallic material specifically at the bearing and end fitting where high strength and load bearing are critical, while using lighter composite material for the tubular sections where weight reduction is prioritized. This localized material selection achieves optimal balance between strength and weight.
Solution Approach 2:
The hybrid metallic-composite construction replaces traditional all-metallic components with a combination of composite tube and metallic bearing/end fitting assembly, reducing overall weight while maintaining load bearing capability through the metallic components at critical interfaces.
3Weight of moving object
If composite tubes are used to interface between metallic structures, then component weight is reduced, but optimized load path implementation becomes complex
Solution Approach 1:
The metallic bearing serves as a mediator that simplifies the load path between composite and metallic components. It provides a straightforward axial load transmission path through its bore, eliminating the need for complex internal composite structures or reinforcement patterns to achieve optimized load paths.
Solution Approach 2:
The component is segmented into distinct functional zones: the composite tube for structural support, the metallic bearing for axial load transmission, and the metallic end fitting for interface with other components. This segmentation allows each part to be optimized independently for its specific function, simplifying the overall design.
Data Source
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AI summary
A metallic-composite joint fitting (200) is provided. The fitting may comprise a composite structure (204), an integral bearing (208) comprising a first frustoconical portion and a second frustoconical portion each having a complimentary shape to the composite structure, a sleeve (216) comprising a third frustoconical portion (222) coupled to a cylindrical bearing surface of the integral bearing, and a metallic end fitting coupled to the third frustoconical portion, wherein the metallic end fitting comprises a bearing portion contacted with the cylindrical bearing surface.