SMA Cable Tension Compensation for Aircraft Sensor Accuracy

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Solution Overview

Problem

Thermal expansion in aircraft cables can cause inaccurate or lost signals in sensor systems, leading to incorrect detection of control surface positions.

Innovation Solution

Incorporating shape-memory alloy (SMA) elements into aircraft assemblies to compensate for cable length changes due to thermal expansion by altering their shape and controlling tension, thereby maintaining accurate signal detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If cable length is allowed to change due to thermal expansion, then the cable can accommodate temperature variations, but the sensor signal becomes inaccurate or is lost

Engineering Contradiction:

Improvethermal expansion accommodationVSAvoidsensor signal accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The SMA element acts as an intermediary component between the cable and sensor. It compensates for cable length changes due to thermal expansion by changing its own shape, thereby maintaining constant cable tension and preventing inaccurate sensor readings while allowing the cable to accommodate temperature variations

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the cable tension is maintained constant, then the sensor signal remains accurate, but the cable cannot accommodate thermal expansion

Engineering Contradiction:

Improvesensor signal accuracyVSAvoidthermal expansion accommodation

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The SMA element changes its physical parameters (shape and length) in response to temperature changes. By controlling the phase transformation temperature and shape change characteristics of the SMA, it can compensate for cable expansion while maintaining constant tension, thus preserving sensor accuracy while adapting to thermal conditions

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a rigid connection is used between cable and sensor, then the signal transmission is stable, but thermal expansion causes signal loss

Engineering Contradiction:

Improvesignal transmission stabilityVSAvoidthermal expansion effect

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system transitions from a rigid static connection to a dynamic adaptive connection using the SMA element. The SMA dynamically adjusts its shape and length based on temperature conditions, maintaining stable signal transmission by compensating for thermal expansion effects in real-time

Inventive Principle:

Principle #15Dynamics

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

The SMA elements effectively offset cable length changes and maintain tension, ensuring precise sensor readings and preventing false indications of control surface skew angles.

Implementation Method 1

a shape-memory alloy (SMA) element connected to the cable, wherein the SMA element is configured to change shape and control tension in the cable

Methodology Applied

Scientific EffectShape memory effect: Shape Memory Alloy

Implementation Method 2

factors such as thermal expansion may affect the length and/or tension of a cable when in use

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS20250382067A1Apparatuses and methods for shape-memory alloys and sensing

Publication Date: 2025.12.18 THE BOEING CO

AI summary

Apparatuses and methods for shape-memory alloy elements and sensing. An aircraft assembly comprising a sensor, a cable connected to the sensor, and a shape-memory alloy (SMA) element connected to the cable. The SMA element is configured to change shape and control tension in the cable. A method of using an aircraft assembly by changing the shape of the SMA element by an amount corresponding to a change in a length of the cable.