Aircraft Fuel Pipe Fixture for Wing Bending and Cryogenic Loads
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Solution Overview
Problem
Aircraft fuel pipes, particularly those conveying hydrogen, experience significant bending and twisting due to wing movement, leading to increased loads on the ribs, exacerbated by cryogenic temperatures requiring thicker pipes and additional structural reinforcement.
Innovation Solution
A double-walled pipe assembly with a fixture arrangement that allows rotation relative to the aircraft structure about multiple axes, using non-conductive materials and bearing surfaces to reduce load transfer and accommodate thermal insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the pipe assembly is rigidly fastened to the ribs, then the pipes are securely positioned relative to the aircraft structure, but the pipes transfer bending and twisting loads into the ribs, requiring additional structural reinforcement
Solution Approach 1:
The fixture arrangement incorporates a rotational degree of freedom that allows the pipe assembly to rotate relative to the aircraft structure. This dynamic capability enables the system to accommodate wing bending and twisting movements while maintaining longitudinal positioning, thereby preventing load transfer to the ribs while preserving position stability.
2Use of energy by moving object
If the pipes convey hydrogen at cryogenic temperatures, then the fuel efficiency is improved, but the pipes require larger thickness for thermal insulation, which increases the loads transferred to the ribs
Solution Approach 1:
The rotational fixture arrangement allows the thickened cryogenic pipe assembly to move independently in response to wing deformations. This dynamic coupling prevents the increased loads from the thicker pipes from being transferred to the ribs, enabling hydrogen fuel efficiency benefits without compromising the structural system.
Solution Approach 2:
The fixture arrangement acts as an intermediary between the cryogenic pipe assembly and the aircraft structure. It provides a controlled connection that restricts longitudinal movement while permitting rotation, thereby mediating the interaction and preventing direct load transfer from the insulated pipes to the ribs.
3Force
If the pipe assembly is allowed to rotate freely, then the loads transferred to the aircraft structure are reduced, but the pipe assembly may experience excessive movement in the longitudinal direction
Solution Approach 1:
The fixture arrangement provides a controlled rotational degree of freedom that allows the pipe assembly to rotate while maintaining longitudinal positioning. This selective dynamic coupling enables load reduction through rotation while preventing excessive longitudinal movement, achieving both objectives simultaneously.
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
The solution effectively mitigates load transfer to the aircraft structure by allowing rotational movement of the pipes, reducing the need for additional structural reinforcement and minimizing thermal transfer, while providing lightning strike protection.
Implementation Method 1
The bearing surfaces may be shaped to provide stop features which restrict movement of at least a portion of the pipe assembly in the longitudinal direction relative to the aircraft structure
Implementation Method 2
curved bearing surfaces forming a bearing therebetween so as to allow rotation of the pipe assembly relative to the aircraft structure
Implementation Method 3
The bearing surfaces are shaped to provide stop features which restrict movement of at least a portion of the pipe assembly in the longitudinal direction relative to the aircraft structure
Data Source
AI summary
An aircraft assembly is disclosed including a wing structure, and a pipe assembly rotatably coupled to the wing structure by a fixture arrangement. The pipe assembly extends along a longitudinal direction, the fixture arrangement configured to restrict movement of at least a portion of the pipe assembly in the longitudinal direction relative to the wing structure and allow rotation of the pipe assembly relative to the wing structure.