Optical Fiber Anchor for Distributed Sensing in Brittle Media
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Solution Overview
Problem
Fiber optic cables with loose interior layers are unsuitable for distributed strain measurements due to slippage within the jacket, while those with tight layers can slip relative to installation media like cement or sand, causing erroneous measurements. Additionally, the spatial resolution of fiber optic distributed sensing systems can result in lower-than-expected or no measurement when the strained fiber length is less than the system's spatial resolution.
Innovation Solution
A fiber optic cable system with resiliently flexible cables and anchors is developed. The cable consists of fiber cores, buffer layers, a strength member, and a jacket, which are secured together at anchoring locations spaced at intervals equal to or greater than the spatial resolution of the sensing system. The anchors engage the installation medium and include ribs defining an infiltration space to ensure secure embedding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fiber optic cable interior layers are made loose, then the cable is more flexible and easier to install, but the loose layers slip within the jacket causing erroneous strain measurements
Solution Approach 1:
The cable structure is segmented into distinct bonding zones (anchoring locations) where layers are bonded together, separated by unbonded zones where layers remain loose. This segmentation allows the cable to maintain flexibility in unbonded sections while ensuring measurement accuracy in bonded sections where strain is transferred to the fiber.
Solution Approach 2:
Different sections of the cable have different bonding characteristics. At anchoring locations, the jacket and strength members are bonded to the fiber core to prevent slippage and ensure accurate strain measurement. Between anchoring locations, the layers remain unbonded to maintain cable flexibility and allow relative movement without affecting measurement integrity.
2Measurement precision
If fiber optic cable interior layers are made tight, then strain measurements are more accurate, but the cable slips relative to installation media like cement or sand causing erroneous measurements
Solution Approach 1:
The cable is divided into discrete anchoring locations spaced at intervals greater than the spatial resolution of the sensing system. At these locations, tight bonding prevents slippage between cable layers and installation media. The spacing ensures that each anchoring location is independently measured, preventing propagation of slippage errors across the entire cable length.
Solution Approach 2:
The anchored cable sections act as intermediaries that transfer strain from the installation media to the fiber core at discrete locations. The anchors embedded in the media provide a reliable interface that prevents slippage, while the spaced arrangement allows the cable to accommodate overall movement without compromising individual measurement points.
3Manufacturing precision
If the length of fiber optic cable experiencing strain is less than the spatial resolution of the sensing system, then measurement becomes impossible or produces lower-than-expected values
Solution Approach 1:
The cable is segmented into discrete anchoring locations spaced at intervals equal to or greater than the spatial resolution of the sensing system. This segmentation ensures that each anchoring location represents a distinct measurement point that can be resolved by the sensing system, preventing signal averaging that would occur with continuous bonding and enabling accurate measurement of small strain zones.
Solution Approach 2:
The problem is solved by transitioning from continuous strain distribution along the cable to discrete strain measurements at specific anchoring locations. This dimensional transformation from continuous to discrete measurement allows the sensing system to detect strain at locations spaced at its spatial resolution limit, effectively overcoming the limitation of small strained lengths.
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 improved monitoring of shear and tension deformations within installation media, enabling accurate crack detection with spatial resolution matching the sensing system, while preventing slippage between cable layers and installation media.
Implementation Method 1
melting the jacket at the anchoring locations via a heating element such as a heat shrink gun
Implementation Method 2
The jacket may then be compressed around the fiber cores at the anchor locations. This may be achieved via shrinking of the jacket as a result of heating
Data Source
AI summary
A fiber optic cable system configured for distributed sensing in a brittle installation medium, the fiber optic cable system comprising a fiber optic cable and a plurality of anchors. The fiber optic cable includes a fiber core, a buffer layer, a strength member, and a jacket. These components are secured together at a number of anchoring locations along the fiber optic cable so that they are bonded together at the anchoring locations and un-bonded from each other between the anchoring locations. The anchors are attached to the fiber optic cable at the anchoring locations and are configured to engage the brittle installation medium to affix the fiber optic cable to the brittle installation medium at the anchoring locations.