Convex Snap Arm for Gas Turbine Cover Plate Stress Reduction

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Solution Overview

Problem

Existing snap configurations in gas turbine rotor cover plates experience high loads and axial shifting during engine operation, leading to detrimental compressive strains that affect the lifecycle of the cover plate.

Innovation Solution

The implementation of a convex radially outward facing contact surface on the cover plate snap arm, with varying curvature and bias configurations, to distribute snap loads effectively and maintain even stress distribution across the cover plate, thereby reducing compressive strains.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing snap configurations are used to maintain contact between cover plate and rotor, then the cover plate position is maintained, but high loads and axial shifting cause large compressive strains that reduce the lifecycle of the cover plate

Engineering Contradiction:

Improvecover plate position stabilityVSAvoidcover plate lifecycle

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The snap arm features a convex radially outward facing contact surface with a specific curvature radius. This curved surface geometry distributes the contact load over a larger area compared to a flat or pointed contact surface, reducing stress concentration and compressive strains on the cover plate while maintaining effective radial contact and position stability.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention modifies the geometric parameters of the snap arm, specifically the curvature radius of the convex contact surface. By optimizing this parameter, the load distribution is improved, reducing compressive strains on the cover plate. Additionally, the snap arm length and thickness are configured to provide appropriate flexibility and load-bearing capacity, balancing position maintenance with strain reduction.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If snaps are used to maintain contact between cover plate and rotor, then radial contact is achieved, but axial shifting during engine operation creates detrimental compressive strains

Engineering Contradiction:

Improveradial contact stabilityVSAvoidcompressive strain on cover plate

Core Design Contradiction:

Stability of the object's compositionVSStress or pressure

Solution Approach 1:

The convex radially outward facing contact surface with optimized curvature radius creates a larger contact area with the rotor. This curvature geometry accommodates axial shifting movements while distributing compressive loads more evenly, reducing stress concentration on the cover plate while maintaining stable radial contact throughout engine operation.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The snap arm is designed with appropriate flexibility through its geometric configuration (length, thickness, and curvature). This allows the snap arm to dynamically adapt to axial shifting movements during engine operation, maintaining radial contact stability while absorbing and distributing compressive strains rather than transmitting them集中 to the cover plate.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11313240B2Rounded radial snap configuration for a gas turbine engine cover plate

Publication Date: 2022.04.26 RTX CORP

AI summary

A rotating machine includes a plurality of rotors. Each of the rotors includes a rotor bore protruding radially inward from a platform. A ring shaped cover plate is interfaced with each rotor bore via at least one snap. The at least one snap includes a first arm extending from the cover plate and having a convex facing contact surface, and multiple second arms extending axially from each rotor bore and having contact surfaces facing the convex surface.