Segmented Metallic Sensor with Optical Fiber for Corrosion Monitoring
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Solution Overview
Problem
Current methods for detecting corrosion in metal structures, particularly reinforced concrete structures, face challenges in accurately differentiating between thermomechanical stresses and corrosion-induced mechanical effects, leading to uncertain corrosion localization and degree estimation, which is essential for condition-based maintenance.
Innovation Solution
A device comprising a metal part with alternating portions covered and uncovered by a corrosion protection layer, where an optical fiber is prestressed in compression to detect stresses, allowing for the differentiation of thermomechanical and corrosion-induced effects through spectral response measurement and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single optical fiber sensor is used to detect corrosion in metal structures, then corrosion detection capability is provided, but the ability to differentiate between thermomechanical stresses and corrosion-induced mechanical effects deteriorates
Solution Approach 1:
The metal structure is segmented into multiple portions (first portions with protection layer, second portions without protection layer) along the longitudinal direction. Each portion is associated with transduction means that can independently measure mechanical effects. This segmentation allows the system to distinguish between thermomechanical stresses (affecting all portions equally) and corrosion-induced effects (affecting only unprotected portions).
Solution Approach 2:
Different portions of the metal structure are given different local qualities: first portions are covered with a corrosion protection layer while second portions are left uncovered. This creates localized differences in corrosion susceptibility that enable the transduction means to differentiate between general thermomechanical stresses and localized corrosion effects by comparing measurements from protected versus unprotected segments.
2Reliability
If scheduled maintenance is performed periodically on large structures, then safety monitoring is ensured, but the time and cost required for inspection increases significantly
Solution Approach 1:
The patent replaces manual visual inspection methods with an automated optical fiber-based transduction system. The transduction means continuously or periodically measure mechanical effects and convert them into spectral responses that indicate corrosion status. This substitution eliminates the need for time-consuming human inspection of large structures while maintaining or improving monitoring reliability.
Solution Approach 2:
The transduction means provide continuous or frequent monitoring of corrosion conditions throughout the structure, rather than relying on discrete periodic inspections. This continuous measurement capability allows for real-time detection of corrosion progression, enabling timely interventions before critical damage occurs, thereby improving reliability without requiring constant human presence.
3Ease of operation
If visual analysis of exterior surfaces is used to assess structure condition, then simple inspection is possible, but the accuracy of corrosion state estimation deteriorates
Solution Approach 1:
The patent introduces transduction means as an intermediary between the metal structure and the measurement system. These transducers are fixed to the structure and provide indirect measurement of corrosion-induced mechanical effects through spectral response analysis. This intermediary approach maintains the simplicity of non-invasive inspection while dramatically improving accuracy by detecting internal stress changes that are not visible from the exterior surface.
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 precise corrosion profiling and thermomechanical stress separation, facilitating effective condition-based maintenance by providing accurate, distributed measurements of corrosion across large metal structures.
Implementation Method 1
an optical fiber, the optical fiber being fixed to the metal part in a prestressed state in compression so as to undergo the stresses undergone by the metal part, the said transduction means being capable of modifying a light propagating in the optical fiber under the effect of stresses applied to the optical fiber
Implementation Method 2
only the first portions being covered with a layer of a corrosion protection material
Data Source
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Figure 4a~5c
Figure 6a~6e
AI summary
Device for measuring the corrosion in a structure. It comprises: at least one assembly, comprising a metallic part (2), intended to be rendered integral with the structure and able to deform under the effect of corrosion and/or a thermomechanical variation, and means of transduction (4) comprising an optical fibre (3) fixed on the metallic part in a prestressed state, the means of transduction being able to modify a light propagating in the fibre under the effect of a stress applied to the fibre; means for measuring and processing the spectral responses provided by the means of transduction of said at least one assembly. The metallic part is segmented longitudinally to form an alternation of segments covered by a protective material (8) for protection against corrosion and of uncovered segments, so as to discriminate the thermomechanical influence of the structure from the mechanical effects induced by corrosion.