Aircraft Propulsion Unit Hanger Attachment Assembly
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Solution Overview
Problem
The existing attachment means for aircraft propulsion units, specifically clevis mounts on composite casings, suffer from deterioration due to strains, leading to delamination and require disassembly of the engine to remove rectifier vanes, compromising reliability.
Innovation Solution
The proposed assembly fixes clevis mounts to the casing's outer periphery, eliminating internal connections and using axial connections with eyelets and fastening means that pass through these eyelets, thereby reducing strain on the casing and preventing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If clevis mounts are fastened to the casing by fastening means passing through the outer shroud and outlet guide vanes, then the attachment structure is achieved, but the composite structure deteriorates due to strains causing delamination
Solution Approach 1:
The attachment system is divided into two separate connection points: one on the outer shroud and another on the outlet guide vanes. This segmentation distributes the mechanical loads across different structural elements, preventing concentration of strains at a single interface and thereby reducing delamination risk in the composite casing.
Solution Approach 2:
The fastening means act as an intermediary element that connects the clevis mount to the casing structure through strategically positioned connection points. By using fastening means that pass through specific structural features (outer shroud and outlet guide vanes) rather than directly through the composite casing, the system mediates the load transfer in a way that protects the composite structure from damaging strains.
2Ease of operation
If clevis mounts are assembled on the casing, then the engine suspension is achieved, but disassembly requires taking down the entire engine
Solution Approach 1:
The attachment system is designed with separable components where the clevis mount can be independently removed from the casing. The fastening means allow the clevis mount to be detached without affecting the outlet guide vanes or requiring engine removal, enabling independent maintenance of the attachment system.
Solution Approach 2:
The clevis mount is designed to be extractable from the casing structure through the fastening means. This allows the clevis mount to be removed and replaced independently, extracting the maintenance task from the complex engine assembly process and enabling simpler, faster repairs.
3Strength
If fastening means pass through outlet guide vanes and intermediate casing, then the clevis mount is secured, but strains deteriorate the composite structure
Solution Approach 1:
The fastening system is designed to engage with specific local structural features (outer shroud and outlet guide vanes) that are optimized for load bearing. By concentrating fastening at these locally strengthened positions rather than distributing it through the composite casing, the system achieves necessary fastening strength while protecting the composite structure from harmful strains.
Solution Approach 2:
The fastening means serve as an intermediary that transfers loads from the clevis mount to the robust metal structures (outer shroud and outlet guide vanes) rather than directly to the composite casing. This mediates the strain distribution, allowing strong attachment while protecting the composite material from delamination-causing stresses.
Data Source
AI summary
An assembly is designed to attach hangers from which an aircraft propulsion unit is suspended. The propulsion unit is intended to be suspended from a structural element of the aircraft. The propulsion unit includes a turbojet engine having a longitudinal axis and the attachment assembly having a clevis mount for attaching the hangers to a casing of the propulsion unit. The clevis mount is fixed to the casing by means designed to form a connection between the clevis mount and the casing at the external periphery of the casing.