Lobed Turbine Shaft Flange Structure for Stress Load Distribution
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Solution Overview
Problem
Current gas turbine engine shaft configurations with flanges face challenges in distributing stress concentrations and load distribution between the tubular base and the flange, leading to potential bending moments and vibration issues.
Innovation Solution
The introduction of a flange support structure with lobes that project radially and axially from the shaft base, forming a lobed configuration with convex and concave sections, which provides structural reinforcement and distributes loads across a larger area, thereby reducing bending moments and enhancing the connection between the shaft flange and base.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a flange is connected to a tubular shaft base, then the shaft can transmit torque and support loads, but stress concentrations occur at the interface between the shaft base and flange
Solution Approach 1:
The flange support structure is segmented into multiple lobes (typically three lobes) arranged circumferentially around the shaft base. Each lobe is a separate structural element that distributes the connection function across multiple locations, reducing stress concentration at any single interface point between the shaft base and flange.
Solution Approach 2:
The lobes extend in multiple dimensions - radially outward from the shaft base and axially between the shaft base and flange - creating a three-dimensional support structure. This multi-dimensional configuration distributes stresses across volume rather than concentrating them at a two-dimensional interface, reducing stress concentrations while maintaining connection strength.
2Stress or pressure
If a fillet is provided at the shaft base-flange interface, then stress concentrations are reduced, but the structural reinforcement and load distribution are insufficient
Solution Approach 1:
The lobed support structure acts as an intermediary element between the shaft base and the flange. Instead of directly connecting the flange to the shaft base (which creates stress concentrations), the lobes serve as intermediate structural members that distribute loads and reinforce the connection, providing both stress reduction and structural strengthening.
Solution Approach 2:
The flange support structure combines multiple geometric features (lobes, grooves, convex and concave sections) into a composite structural configuration. This composite design integrates both stress-reducing fillet-like features and load-distributing reinforcement elements into a single integrated structure that achieves both objectives simultaneously.
3Device complexity
If the flange is directly connected to the shaft base, then the structure is simple, but bending moments and vibrations cause load distribution issues
Solution Approach 1:
The support structure is divided into multiple lobes arranged circumferentially, with each lobe providing independent structural support. This segmentation increases resistance to bending moments by distributing loads across multiple discrete support points, improving reliability without requiring a completely complex multi-component assembly.
Solution Approach 2:
The lobes feature curved surfaces with convex outer peripheries and concave inner surfaces, creating smooth transitions that reduce stress concentrations. The curved geometry provides structural reinforcement against bending moments while maintaining a relatively simple monolithic structure that integrates well with the shaft and flange.
Data Source
AI summary
An apparatus for a gas turbine engine includes a shaft base, a flange and a plurality of lobes. The shaft base extends axially along an axis between a shaft first end and a shaft second end. The flange is connected to the shaft base at the shaft first end. The flange projects radially out from the shaft base. The flange includes a plurality of fastener apertures, and the fastener apertures include a first fastener aperture. The lobes are arranged circumferentially about the axis. Each of the lobes is connected to and projects radially away from the shaft base. Each of the lobes is connected to and projects axially out from the flange. The lobes include a first lobe and a second lobe. The first fastener aperture is arranged circumferentially between the first lobe and the second lobe. The second lobe radially overlaps the first fastener aperture.