Shape Memory Alloy Guide Tube for Indirect Gas Turbine Inspection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing inspection tools for gas turbine engines face challenges in accessing indirectly accessible cavities, requiring complex tooling and often leading to engine removals due to issues like powder metal defects, necessitating improved tool guidance and straightening mechanisms.

Innovation Solution

Utilization of smart metal alloy (SMA) guide tubes that can be memorized into bent shapes, heated to return to those shapes, and straightened for insertion and removal, facilitating inspection of inaccessible areas with integrated scopes and elements like boroscopes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a straight rigid inspection tool is used, then the tool structure is simple, but the tool cannot access indirectly accessible cavities

Engineering Contradiction:

Improveaccessibility to cavityVSAvoidtool structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The guide tube is made dynamically changeable between straight and bent configurations through thermal activation of the shape memory alloy. When heated, the guide tube transitions from a straight insertion configuration to a bent inspection configuration, allowing the same tool to perform both insertion and cavity access functions without requiring multiple separate components.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The physical state of the guide tube is changed through temperature parameter variation. By controlling the temperature (heating or cooling), the guide tube's shape changes between straight and bent states, enabling it to adapt to different operational requirements - straight for insertion, bent for cavity access - thus resolving the contradiction between structural simplicity and accessibility.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If a bent guide tube is used to access the cavity, then the inspection capability is improved, but the guide tube cannot be easily removed from the engine

Engineering Contradiction:

Improveinspection capabilityVSAvoidremoval difficulty

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The guide tube's shape is made dynamically controllable through thermal activation. After inspection, the guide tube is heated to return to its straight memorized shape, which allows it to be easily withdrawn from the engine cavity. This dynamic shape control enables the tube to be bent for inspection but straight for removal, resolving the contradiction between inspection capability and removal ease.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The guide tube performs the straightening action automatically through thermal activation without requiring external manipulation tools. The shape memory effect causes the tube to self-return to its memorized straight configuration when heated, facilitating easy removal from the engine cavity and eliminating the need for complex extraction mechanisms.

Inventive Principle:

Principle #25Self-service

3Ease of operation

If the guide tube is heated to return to bent shape, then the inspection element can reach the cavity, but energy consumption increases

Engineering Contradiction:

Improveinspection element positioningVSAvoidheating energy

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The mechanical system of manually manipulating flexible or segmented tubes is replaced with a thermal-field-based shape memory alloy system. The heating energy activates the intrinsic shape memory effect of the SMA material, causing automatic shape transformation. This substitution reduces the need for complex mechanical actuation mechanisms and allows precise shape control through controlled thermal input.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The shape memory alloy undergoes a phase transition (martensitic to austenitic transformation) when heated, which drives the shape recovery. This phase transition mechanism allows the guide tube to achieve its bent configuration through controlled thermal input, efficiently converting thermal energy into mechanical shape change and enabling inspection element positioning without excessive energy consumption.

Inventive Principle:

Principle #36Phase transitions

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables effective inspection of inaccessible gas turbine engine cavities without damaging components, reducing engine removals and improving inspection efficiency by allowing curved tool guidance and easy straightening post-inspection.

Implementation Method 1

heating the guide tube to cause the guide tube to return to the bent shape

Methodology Applied

Scientific EffectShape memory alloy effect: Shape Memory Alloy

Data Source

PatentUS20250284113A1Use of memorized alloy for inaccessible location

Publication Date: 2025.09.11 RTX CORP

AI summary

A method of inspecting an indirectly accessible cavity of a gas turbine engine is provided. The method includes memorizing a guide tube formed of smart metal alloy (SMA) into a bent shape and straightening the guide tube. The method also includes installing a scope, which includes a connecting line to which an inspection element is attached, into the guide tube. The method then includes inserting the guide tube into the gas turbine engine toward a location of the indirectly accessible cavity, heating the guide tube to cause the guide tube to return to the bent shape in order to bring the inspection element into the indirectly accessible cavity and using the inspection element to perform an inspection of the indirectly accessible cavity.