Composite Pylon Double-Shear Connections and Segmentation
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Solution Overview
Problem
Incorporating composite materials into aircraft engine pylons poses challenges such as meeting damage tolerance and fail-safety requirements, especially when exposed to high temperatures, which often necessitates the use of costly materials and complex manufacturing techniques.
Innovation Solution
A composite pylon design featuring double-shear connections and fail-safe alternate load paths, with components made of elevated or high-heat grade materials, including metallic and heat-resistant materials, to accommodate substantial loads and distribute temperature stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a monolithic composite structure is used in close proximity to concentrated high temperatures, then the structural integrity is maintained, but the manufacturing cost increases and manufacturing complexity increases
Solution Approach 1:
The pylon is divided into multiple composite components (forward engine support, outer structural section, inner structural section, aft engine supports, airframe attachment components, stabilizer components) that can be manufactured separately using appropriate materials and processes for each location's thermal exposure, then assembled together. This allows standard materials to be used in low-temperature zones while expensive high-heat resistant materials are only used where thermally exposed.
Solution Approach 2:
Different regions of the pylon are assigned different material properties based on their thermal environment. The outer structural section and components near the engine exhaust are made of heat-resistant composite materials, while components in cooler zones use standard composite materials. This local differentiation reduces overall material cost while maintaining structural integrity where needed.
2Strength
If a monolithic composite structure is used in close proximity to concentrated high temperatures, then the structural integrity is maintained, but the manufacturing cost increases
Solution Approach 1:
By segmenting the pylon into separate manufacturable components, the patent enables use of cost-effective composite materials in the majority of the structure while reserving expensive high-temperature resistant materials only for thermally exposed areas, thereby reducing overall manufacturing cost.
Solution Approach 2:
The patent applies different material quality levels to different locations based on thermal exposure requirements, avoiding the need to manufacture the entire pylon from expensive high-heat resistant materials, thus reducing manufacturing cost while maintaining integrity where thermally loaded.
3Weight of moving object
If composite materials are used to reduce weight, then the weight is reduced, but meeting damage tolerance and fail-safety requirements becomes difficult
Solution Approach 1:
The patent incorporates metallic reinforcement elements and multiple attachment interfaces that provide redundant load paths and damage tolerance before failure occurs. The metallic components act as cushioning elements that can accommodate damage in the composite structure while maintaining overall structural integrity, ensuring fail-safety requirements are met.
Solution Approach 2:
The patent uses hybrid composite structures combining composite materials with metallic reinforcement elements. The composite materials provide weight reduction while the metallic elements provide damage tolerance and fail-safety characteristics, achieving both weight reduction and reliability requirements simultaneously.
4Force
If metallic materials are used for attachment interfaces to accommodate high loads, then the load bearing capacity is improved, but the weight increases
Solution Approach 1:
The patent employs composite materials with high specific strength for attachment interfaces and load-bearing components, achieving the required load bearing capacity while minimizing weight. The composite materials are selected and configured to provide necessary mechanical properties without the weight penalty of traditional metallic alternatives.
Data Source
AI summary
A composite aircraft engine pylon comprising a frame, an aircraft attachment component, and an engine support. The frame includes an outer structural section and an inner structural section configured to at least partially nest with the outer structural section. The outer structural section and the inner structural section sandwich the airframe attachment component and the engine support to form double shear connections between the frame and the aircraft attachment component and between the frame and the engine support.