Geared Turbofan Shaft-Gearbox Coupling with Logarithmic Profile
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Geared turbo fan engines face challenges in effectively transmitting torque between the turbine section and the propulsive fan while minimizing weight and maximizing torsional stiffness, as existing coupling devices struggle to efficiently handle mechanical loads and maintain structural integrity.
Innovation Solution
A coupling device with a logarithmic or power profile is used to radially connect the shaft and gearbox, providing high torsional stiffness with minimal weight penalty, featuring a curved shape with varying cross-sectional thickness and asymptotic approaches at torque input/output points, optimized for stress and fatigue resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional coupling device is used to connect the shaft and gearbox, then the structure is simple and easy to manufacture, but the torsional stiffness is insufficient and weight is excessive
Solution Approach 1:
The coupling device employs a logarithmic or power profile shape that varies the cross-sectional area along its length, optimizing the distribution of material to maximize torsional stiffness while minimizing weight. This parametric approach to geometry allows the coupling to achieve high stiffness-to-weight ratio by concentrating material where it is most effective for torsional resistance.
Solution Approach 2:
The coupling device may utilize composite material construction, combining materials with different properties to achieve optimal torsional stiffness at reduced weight. The use of composite materials allows for tailored mechanical properties that can simultaneously satisfy strength and weight requirements.
2Reliability
If the coupling device thickness is uniform, then manufacturing is simpler, but stress distribution is suboptimal and fatigue resistance is reduced
Solution Approach 1:
The coupling device features variable cross-sectional thickness that is optimized for local stress conditions. The thickness is greatest where stresses are highest and tapers to smaller dimensions where less structural support is needed. This local quality approach ensures optimal fatigue resistance by matching material distribution to the actual stress profile, while the logarithmic or power profile provides a manufacturable geometry.
3Strength
If the coupling device is made heavier, then torsional stiffness increases, but weight penalty increases and engine efficiency decreases
Solution Approach 1:
The logarithmic or power profile shape optimizes the parametric distribution of material along the coupling device, achieving maximum torsional stiffness for minimum weight. This parametric optimization ensures that the coupling device provides the necessary structural performance without excessive weight that would penalize engine efficiency.
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
The invention is related to a Coupling device (1) for rotably coupling a shaft (4) with a gearbox (14) in a geared turbo fan aircraft engine (10), wherein the coupling device (1) comprises a connection to the shaft (4) at a first end (A) and a connection to the gearbox (14) at a second end (B), the first and the second ends (A, B) being axially separated and at least one curved shape between the first end (A) and the second end (B) extending from the gearbox (14) radially inwards to the shaft (4) and the at least one curved shape comprising at least one cross-section in the axial direction of the engine (1) with a logarithmic profile (L) or a power profile.