Aircraft Pipe Fixture With Curved Bearing for 3-Axis Rotation
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Solution Overview
Problem
Hydrogen fuel lines in aircrafts are thick and span long distances, bending and twisting with the wing, requiring fixture arrangements that minimize stress concentrations while allowing for rotational movement to accommodate design tolerances and reduce manufacturing lead times.
Innovation Solution
Aircraft assembly with a pipe assembly and fixture arrangement featuring a curved bearing surface allowing rotation about three perpendicular axes, restricted by stop members to limit axial movement, and a contact surface that increases radially to maintain consistent contact and reduce stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fixture arrangement is used to restrict axial movement of the pipe assembly, then axial position stability is improved, but rotational movement capability deteriorates
Solution Approach 1:
The fixture arrangement incorporates a curved bearing surface with curvature in two orthogonal directions that contacts the pipe assembly. This curved geometry enables the pipe assembly to rotate relative to the fixture arrangement about three perpendicular axes while maintaining axial position stability, resolving the contradiction between stability and rotational capability
Solution Approach 2:
The fixture arrangement is designed to be dynamic rather than rigidly fixed, allowing the pipe assembly to rotate and adapt to wing bending and twisting. The curved bearing surface provides a controlled interface that permits rotational movement while maintaining axial restriction
2Device complexity
If a simple stop member design is used to restrict axial movement, then device complexity is reduced, but manufacturing precision requirements worsen
Solution Approach 1:
The stop member features a contact surface with curvature in two orthogonal directions that matches the curved bearing surface of the fixture arrangement. This curved geometry design provides a self-aligning mechanism that reduces sensitivity to manufacturing tolerances, allowing simpler fabrication while maintaining functional precision
Solution Approach 2:
The invention changes the geometric parameters of the contact surfaces from flat to curved, with specific curvature radii that accommodate rotational movement and reduce the impact of manufacturing variations. This parameter change simplifies the overall design while maintaining adequate precision
3Adaptability or versatility
If the contact surface distance increases radially from the pipe axis, then rotational movement consistency is improved, but stress concentration worsens
Solution Approach 1:
The contact surfaces of both the fixture arrangement and stop member have curvature in two orthogonal directions. This matched curvature distribution ensures consistent contact across the radial distance increase, maintaining rotational movement consistency while distributing stresses more evenly to reduce stress concentrations
Data Source
AI summary
An aircraft assembly including: an aircraft structure; a pipe assembly; a fixture arrangement attached to the aircraft structure, the fixture arrangement contacting the pipe assembly via a curved bearing surface having curvature in two orthogonal directions; the curved bearing surface configured to enable the pipe assembly to rotate relative to the fixture arrangement about three perpendicular axes; wherein the pipe assembly comprises a stop member adjacent the fixture arrangement, a contact surface of the stop member configured to abut a contact surface of the fixture arrangement so as to restrict axial movement of the pipe assembly relative to the fixture arrangement, and wherein a distance between the contact surface of the fixture arrangement and the contact surface of the stop member increases radially from the longitudinal pipe axis.