Aircraft Engine Strut Assembly Straight Ligament Design
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Solution Overview
Problem
The existing strut assemblies in gas turbine engines face challenges in withstanding both static and dynamic forces while maintaining a lightweight design, as they are typically formed in a robust manner to handle these forces, leading to increased weight and potential structural inefficiencies.
Innovation Solution
The proposed strut assembly features an outer structural case with mounting pads and case ligaments extending in substantially straight directions, which improves the structural load-carrying capability and reduces bending stress, allowing for better force distribution and weight efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strut assembly is formed in a robust manner to withstand static and dynamic forces, then the strength and reliability are improved, but the weight of the strut assembly increases
Solution Approach 1:
The outer structural case is divided into multiple discrete ligaments (first ligament, second ligament, third ligament, fourth ligament) that connect mounting pads. This segmentation allows each ligament to be optimized for specific load paths while reducing overall material usage compared to a solid robust structure.
Solution Approach 2:
The ligaments are positioned and dimensioned to provide localized structural support where needed. The first and second ligaments connect mounting pads for first-stage fan blades, while the third and fourth ligaments connect mounting pads for second-stage fan blades, creating locally optimized structural properties rather than uniform robust construction throughout.
2Reliability
If the strut assembly is formed in a robust manner to withstand static and dynamic forces, then the reliability is improved, but the overall weight of the strut assembly increases
Solution Approach 1:
The outer structural case is divided into multiple discrete ligaments (first ligament, second ligament, third ligament, fourth ligament) that connect mounting pads. This segmentation allows each ligament to be optimized for specific load paths while reducing overall material usage compared to a solid robust structure.
Solution Approach 2:
The ligament structure exhibits asymmetric positioning and configuration to match the asymmetric load patterns experienced during operation. The first and second ligaments are positioned to handle loads from first-stage fan blades, while the third and fourth ligaments handle loads from second-stage fan blades, creating an asymmetric but optimized reliability structure.
3Stability of the object's composition
If traditional curved case ligaments are used, then the structural continuity is maintained, but the bending stress and interlaminar stress increase
Solution Approach 1:
Instead of using curved ligaments that follow the circular contour of the outer case (traditional approach), the invention inverts the approach by using substantially straight ligaments that extend radially outward from the hub. This inversion eliminates bending moments in the ligaments while maintaining structural continuity through the mounting pad connections.
Solution Approach 2:
The invention deliberately avoids curvature in the ligaments, using substantially straight configurations instead. The first ligament extends substantially straight from a first mounting pad to a second mounting pad, and similarly for the other ligaments, eliminating the bending stresses that would result from curved geometries.
Data Source
AI summary
A strut assembly for a gas turbine engine includes an outer structural case. The outer structural case includes a first mounting pad for mounting a first strut and a second mounting pad for mounting a second strut. The outer structural case further includes a case ligament extending between the first mounting pad and the second mounting pad in a substantially straight direction to reduce an amount of bending stress on the outer structural case.