Fiber Optic Cable Strain Locking for Harsh Environments
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Solution Overview
Problem
Optical fibers used in harsh oil well environments face challenges in accurately measuring strain beyond the elastic limit of materials due to their fragility and the need for reliable attachment within protective sheaths, while existing systems often fail to operate effectively in high temperature, high pressure, and corrosive conditions.
Innovation Solution
A fiber optic cable arrangement with a core and sheath where the optical fibers are strain locked to the core and sheath, utilizing a helical configuration and adhesive for efficient strain transfer, allowing the system to operate beyond the elastic limits of its materials, with the sheath's tensile strength exceeding the core's for reliable deformation measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical fiber is attached to structure over measurement span, then measurement accuracy is improved, but fiber fragility causes reliability deterioration
Solution Approach 1:
A protective sheath is introduced as an intermediary component between the optical fiber and the external environment. The sheath protects the fragile fiber while allowing strain transmission through adhesive bonding, resolving the contradiction between measurement accuracy and fiber reliability in harsh environments.
Solution Approach 2:
The system uses composite construction with the optical fiber embedded in adhesive material within the protective sheath. This composite structure allows the fiber to be protected while maintaining strain sensitivity, enabling both accurate measurement and reliable operation.
2Adaptability or versatility
If system operates beyond elastic limit of materials, then measurement capability is improved, but material failure risk increases
Solution Approach 1:
The system changes the operational parameters by allowing the structure to deform beyond the elastic limit of its materials into the plastic deformation region. The optical fiber, being linearly elastic over a wider range, can measure these larger deformations, expanding the measurement capability while the protective sheath and adhesive system maintain structural integrity.
3Measurement precision
If adhesive is used to strain lock fiber to core, then strain transfer efficiency is improved, but adhesive debonding under shear force becomes a risk
Solution Approach 1:
The adhesive is applied in specific locations and configurations within the sheath to optimize strain transfer while managing shear forces. The local application of adhesive creates effective strain locking points without requiring complete coverage, reducing the risk of debonding while maintaining measurement accuracy.
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 accurate strain measurement and shape sensing in harsh environments, ensuring reliable data transmission and system health monitoring by effectively transferring large strains and tolerating shear forces without debonding, even in non-ideal adhesive situations.
Implementation Method 1
at least one optical fiber positioned within the sheath being strain locked to the core
Implementation Method 2
utilizing a helical configuration and adhesive for efficient strain transfer, allowing the system to operate beyond the elastic limits of its materials
Data Source
AI summary
A fiber optic cable arrangement includes a core, a sheath surrounding the core and being strain locked to the core, and at least one optical fiber positioned within the sheath being strain locked to the core.