Flexible Test Body for Endogenous Deformation Measurement

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Solution Overview

Problem

Current methods for measuring endogenous deformations in structures during solidification, such as in cementitious matrices, are invasive and provide only average stress or deformation estimates, leading to potential crack initiation and inaccurate long-term deformation predictions.

Innovation Solution

A device comprising non-intrusive, flexible test bodies with integrated optical measurement fibers and strain sensors, such as Bragg gratings or Fabry-Pérot cavities, that allow precise measurement of deformations in multiple directions, minimizing the risk of buckling and ensuring accurate, local deformation tensor analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a uniaxial sensor or measuring fiber is integrated into the structure volume, then deformation measurement capability is improved, but the structure is weakened due to stress distribution modification and local stress concentrations that can lead to crack initiation

Engineering Contradiction:
Improvedeformation measurement capabilityVSAvoidstructure strength
Core Design Contradiction:
Measurement precisionVSStrength

Solution Approach 1:

The patent employs flexible test bodies made of elastomeric materials that can deform with the structure without creating stress concentrations. These flexible shells encapsulate the measurement fibers and transmit deformations while maintaining structure integrity, thus resolving the contradiction between measurement capability and structural strength.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent introduces flexible test bodies as intermediary elements between the structure and the measurement fibers. These test bodies act as mediators that transmit structural deformations to the measurement system without requiring direct integration of fragile sensors into the structure, thereby preserving structural integrity while enabling precise measurements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If external sensors are placed on the structure surface, then structure integrity is maintained, but only average stress or deformation estimates can be obtained

Engineering Contradiction:
Improvestructure integrityVSAvoiddeformation estimation accuracy
Core Design Contradiction:
StrengthVSMeasurement precision

Solution Approach 1:

The flexible test bodies serve as intermediary elements that bridge the gap between external placement and internal measurement. They are placed on the structure surface like external sensors but contain and transmit local deformation information to measurement fibers, enabling precise local measurements while maintaining structure integrity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent transitions from surface-level external sensing to a three-dimensional measurement approach by embedding measurement fibers within flexible test bodies that can capture deformations in multiple directions and dimensions, thereby obtaining comprehensive local deformation tensors rather than simple surface measurements.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Measurement precision

If multiple uniaxial sensors are scattered in the measurement volume, then local deformation components can be measured, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvelocal deformation component measurementVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple measurement capabilities into a single integrated flexible test body containing multiple measurement fibers oriented in different directions. This merging approach eliminates the need to scatter multiple separate sensors throughout the volume, reducing device complexity while maintaining the ability to measure local deformation components in three dimensions.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The flexible test body is designed as a universal measurement unit that can simultaneously measure deformations in multiple directions using embedded measurement fibers. This multi-functional design replaces the need for multiple separate uniaxial sensors, simplifying the overall device architecture while comprehensive deformation analysis.

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

This solution provides reliable, precise measurements of endogenous deformations, reducing the risk of crack formation and improving the accuracy of long-term deformation predictions by directly measuring deformation components in six dimensions, thus enhancing the quality and reliability of deformation monitoring.

Implementation Method 1

a measurement fiber (7), extending into said channel, at least one part (71) of which is fixed inside said test body, so that deformations undergone by said test body are transmitted to said measurement fiber (7)

Methodology Applied
Scientific EffectOptical fiber measurement: Optical Fibre

Implementation Method 2

Bragg gratings or Fabry-Pérot cavities, that allow precise measurement of deformations

Methodology Applied
Scientific EffectBragg grating: Bragg Diffraction

Implementation Method 3

Bragg gratings or Fabry-Pérot cavities, that allow precise measurement of deformations

Methodology Applied
Scientific EffectFabry-Pérot cavity: Fabry-Perot Interferometer

Data Source

PatentEP3449208B1Device for measuring endogenous deformations
Publication Date: 2021.10.06 CENT NAT DE LA RECH SCI (C N R S)
  • EP3449208B1 patent drawingFigure 1~2
  • EP3449208B1 patent drawingFigure 3
  • EP3449208B1 patent drawingFigure 4

AI summary

Device for measuring endogenous deformations of a structure (1) of materials, during the passage of said structure from a liquid phase to a solid phase, comprising: a uniaxial test body (5) suitable for being embedded in the structure; a deformation-measuring fibre (7) attached to the interior of the test body; and a system (9, 10, 11) that is connected to the measuring fibre (7) and suitable for detecting signals representative of the deformations of the measuring fibre and for determining endogenous deformations from these signals and known mechanical properties of the materials of the test body (5), the test body having a rigidity comprised between 2 and 5 gigapascals.