Optical Fiber Sensor for Building Displacement Profile Measurement

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Solution Overview

Problem

Existing methods for determining displacements profiles in building structures, such as bridges or geotechnical structures, fail to accurately account for temperature variations and axial forces, especially when the sensing elements are constrained by the medium they are measuring, leading to incorrect interpretation of measurement data.

Innovation Solution

A sensor with a core containing coupled optical fiber sensing elements for strain measurement and a freely placed optical fiber sensing element for temperature determination, located within the neutral axis of the core, allowing for continuous compensation of ambient temperature influences and accurate measurement of medium displacements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical fiber sensing elements are constrained by the medium being measured, then measurement integration is improved, but temperature compensation becomes inaccurate

Engineering Contradiction:

Improvemeasurement integrationVSAvoidtemperature compensation accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The sensor divides temperature compensation into two independent segments: a first optical fiber sensing element that measures temperature while constrained by the medium, and a second optical fiber sensing element that measures temperature while free from medium constraints. This segmentation allows each element to fulfill its specific measurement function accurately without interference from the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a reference medium (such as air or insulation material) as an intermediary environment for the second optical fiber sensing element. This intermediary allows the second element to measure temperature without being constrained by the tested medium, providing a pure temperature reference for compensation calculations.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If a single optical fiber sensing element is used for both temperature and strain measurement, then device complexity is reduced, but measurement accuracy deteriorates

Engineering Contradiction:

Improvesensor structureVSAvoiddisplacement profile measurement

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent merges multiple optical fiber sensing elements (both constrained and unconstrained) into a single integrated sensor assembly. This combination allows simultaneous measurement of temperature, strain, and displacement profile through multiple fibers working together, achieving high measurement accuracy while maintaining relatively simple device structure through unified signal processing.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The sensor system achieves multi-functionality by using optical fiber sensing elements that can simultaneously measure temperature, strain, and displacement profile. The first optical fiber provides temperature and strain data, while the second optical fiber provides temperature reference, enabling the system to perform multiple measurement functions with a unified sensor design.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 continuous, accurate measurement of displacements profiles in building structures by isolating temperature effects and accounting for strains caused by bending, twisting, and axial forces, providing reliable data even under constrained conditions.

Implementation Method 1

optical fiber sensing elements for determining the core strains

Methodology Applied

Scientific EffectOptical fiber strain sensing: Photoelasticity

Implementation Method 2

optical fiber sensing element for determining temperature

Methodology Applied

Scientific EffectOptical fiber temperature sensing: Thermal Expansion

Implementation Method 3

allowing for continuous compensation of ambient temperature influences

Methodology Applied

Scientific EffectTemperature compensation: Thermal Expansion

Data Source

PatentEP3314202B1Method for measuring the displacement profile of buildings and sensor therefor

Publication Date: 2022.09.28 SHM SYST SP ZOO SP KOMANDYTOWA

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AI summary

The present invention provides a method for continuous measurement of displacements profile of building structures and a sensor for implementation of this method for repeated, automatic displacements profile measurements of the medium by means of optical fiber elements, especially in engineering structures, engineering structure elements, geotechnical structures, and an apparatus for implementation of this method, characterized in that the measurement involves a measuring sensor, which is constructed of the a core with coupled optical fiber sensing elements for determining the core strains and an optical fiber sensing element for determining temperature, placed freely in an axial channel of the core, making possible to perform measurements in such a way, which allows for compensation of the influence of ambient temperature.