Optical Fiber Strain Sensor with Release Layer for Cable Monitoring
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Solution Overview
Problem
Conventional optical-fiber strain sensors face difficulties in accurately measuring strain in cables due to the high strip force required to remove protective layers, which can damage the optical fiber and disrupt its properties, while reducing adhesion to improve strippability compromises mechanical congruence and strain transferability.
Innovation Solution
A strain sensor design incorporating a thin release layer, typically made of silicone polymer, fluoropolymer mixture, or extruded polymer with a slip agent, between the optical fiber and protective layers, allowing for easy removal without damaging the fiber and maintaining mechanical congruence with the cable conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tighter configuration is used for the buffer layer to adhere to the optical fiber coating system, then strain transferability is improved, but strip force increases and may damage the optical fiber
Solution Approach 1:
A release layer is introduced as an intermediary between the optical fiber coating system and the buffer layer. This release layer has controlled adhesion properties that allow it to transfer strain effectively while enabling easy removal during stripping operations without damaging the optical fiber coating system.
Solution Approach 2:
The adhesion parameters of the buffer layer are modified by introducing a release layer with specific material properties. The release layer has optimized adhesion strength that balances strain transfer capability with strippability, allowing the buffer layer to adhere sufficiently for strain monitoring while being removable without damage.
2Ease of operation
If adhesion between the buffer layer and optical fiber coating system is reduced to improve strippability, then ease of operation is improved, but mechanical congruence and strain transferability deteriorate
Solution Approach 1:
The release layer serves as a mediator with intermediate adhesion properties. It provides sufficient adhesion to the optical fiber coating system for strain transfer while providing controlled adhesion to the buffer layer that enables easy removal during stripping, thus resolving the contradiction between strippability and strain transferability.
Solution Approach 2:
Different adhesion qualities are created at different interfaces: the release layer has optimized adhesion to the optical fiber coating system for strain transfer, while its adhesion to the buffer layer is controlled to enable easy removal. This local differentiation of adhesion properties resolves the contradiction.
Data Source
Figure 1a
Figure 1b~2b
Figure 3
AI summary
A cable includes a longitudinal structural element including at Ieast one of an electrical conductor and an optical conductor, and a strain sensor arranged within a bending neutral region of the cable and mechanically coupled with the longitudinal structural element. The strain sensor includes an optical fiber coated with at least one coating layer, a release layer surrounding the coating layer, and a protective layer surrounding the release layer. The release layer includes a material selected from a silicone polymer, a fluoropolymer mixture or an extruded polymer containing a slip agent.