Digital Strain Encoder Segmentation for Structural Health Monitoring

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Solution Overview

Problem

Existing strain sensors lack sensitivity for structural health monitoring, require thermal matching with the underlying material, and can experience electrical drift on certain engineered materials, degrading signal quality near small strain fields.

Innovation Solution

A digital strain encoder system comprising a gage-emitter, sensor-receiver, transmitter, and temperature sensor, where the gage-emitter deforms with the surface to emit reference and altered strain signals, and the sensor-receiver detects these signals without deforming, allowing for wireless transmission and operation on any material without thermal matching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single long continuous circuit of thin foil is used as the sensor gage, then the device can be manufactured with simple structure, but the sensitivity for structural health monitoring is insufficient due to signal averaging over the entire length

Engineering Contradiction:

Improvestrain measurement sensitivityVSAvoidsensor gage structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the sensor gage into multiple discrete strain-sensitive elements arranged in a specific pattern rather than using a single continuous circuit. This segmentation allows the sensor to detect strain at multiple locations simultaneously, preventing signal averaging and improving measurement sensitivity for structural health monitoring applications.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the sensor gage is thermally matched with the underlying material, then thermal stability is improved, but the device cannot be used on engineered materials such as composites where thermal matching is difficult

Engineering Contradiction:

Improvematerial compatibilityVSAvoidelectrical drift

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the thermal matching approach with a mechanical bonding approach. The sensor gage elements are mechanically bonded to the surface of the test object, and strain is measured through direct mechanical coupling rather than thermal expansion matching. This eliminates electrical drift issues on composite materials while maintaining measurement reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If the sensor gage measures strain over the entire length of the foil circuit, then the device can operate on any material surface, but the signal near small strain fields is degraded due to averaging with unaffected length

Engineering Contradiction:

Improvesmall strain field detectionVSAvoidmeasurement coverage

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent uses multiple discrete strain-sensitive elements positioned at specific locations rather than a continuous circuit. This allows the sensor to concentrate measurement capability on areas of interest while maintaining the ability to monitor multiple locations, improving detection of small strain fields without sacrificing overall measurement coverage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent concentrates strain-sensitive elements in regions where strain gradients are expected or where critical measurements are needed, rather than distributing sensitivity uniformly across the entire sensor length. This local concentration of sensing capability improves detection of small strain fields while maintaining adequate coverage through strategic element placement.

Inventive Principle:

Principle #3Local quality

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 system provides enhanced sensitivity for structural health monitoring, detects strain directly, and operates on any material, reducing signal degradation and electrical drift issues, enabling accurate strain measurement and crack detection.

Implementation Method 1

The strain gage elements emit an identification signal and a reference strain signal and an altered strain signal when deformed

Methodology Applied

Scientific EffectStrain-induced optical signal alteration:

Implementation Method 2

The serialization elements are positioned adjacent to the strain gage elements and emit a serialization signal

Methodology Applied

Scientific EffectLight emission from LED elements: Light Emitting Diode

Data Source

PatentUS8307715B2Directly applied read and transmit—digital strain encoder and digital load cell

Publication Date: 2012.11.13 GE INFRASTRUCTURE TECH LLC

AI summary

A digital strain encoder includes a gage-emitter, a sensor-receiver, a transmitter, and an energy source. The gage-emitter is affixable to a surface to be measured and deformable on a one-to-one basis with the surface, and emits a reference strain signal in the absence of strain and an altered strain signal when the surface is subjected to strain and the gage-emitter is deformed. The gage-emitter also emits a unique reference identification signal. The sensor-receiver floats over the gage-emitter so as not to deform with the surface, and detects the reference and altered strain signals and the identification signal emitted by the gage-emitter. The transmitter is coupled to the sensor-receiver for transmitting the detected reference and altered strain signals to a remote receiver.