Friction Layer in TR-ADSS Optical Fiber Cables
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Solution Overview
Problem
All-Dielectric Self Supporting (ADSS) optical fiber cables, particularly track-resistant ADSS cables, experience 'corkscrewing' failures due to slippage between the outer jacket and the aramid yarn wrap, which is exacerbated by the use of separating tapes like Mylar, leading to inadequate bonding and structural instability during installation.
Innovation Solution
Incorporating a high friction layer between the aramid yarn wrap and the outer jacket, specifically using polymer friction tapes with asymmetrical friction surfaces, to enhance the bonding and prevent slippage, thereby addressing the 'corkscrewing' issue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a separating tape (Mylar) is used between the aramid yarn wrap and outer jacket to prevent sticking during extrusion, then the outer jacket can be successfully extruded without adhering to the inner jacket, but the outer jacket slips and twists around the inner core under tensile and torsion loads during installation
Solution Approach 1:
The patent introduces a friction layer as an intermediary component between the aramid yarn wrap and outer jacket. This friction layer has asymmetric friction properties: a low friction surface facing the outer jacket to prevent sticking during extrusion, and a high friction surface facing the aramid yarn wrap to prevent slippage during installation. This mediator resolves the contradiction by providing different friction characteristics for different operational phases.
Solution Approach 2:
The friction layer exhibits local quality through its asymmetric friction surfaces. One surface has low friction coefficient to facilitate extrusion, while the other surface has high friction coefficient to prevent slippage during installation. This local differentiation of friction properties allows the same component to serve dual functions in different operational contexts.
2Adaptability or versatility
If the aramid yarn wrap is applied to support the cable weight over long aerial runs, then the cable can accommodate variations in load due to temperature, wind, and ice, but the outer jacket slips and twists around the inner core when high tensile and torsion loads are imposed during installation
Solution Approach 1:
The friction layer serves as a mediator between the aramid yarn wrap and outer jacket, providing controlled friction characteristics. The high friction surface on the aramid yarn side prevents slippage during installation under high loads, while maintaining the aramid yarn's ability to accommodate load variations during operation.
Solution Approach 2:
The friction layer changes the friction parameter at the interface between aramid yarn and outer jacket. By introducing a layer with specifically engineered friction properties, the system achieves both structural stability during installation and adaptability during operation, resolving the contradiction between these two requirements.
3Ease of manufacture
If the outer jacket is extruded as molten material, then it can form a protective covering, but it sticks to the inner jacket during the extrusion process
Solution Approach 1:
The friction layer acts as an intermediary between the inner jacket and outer jacket during extrusion. Its low friction surface facing the outer jacket prevents the molten material from sticking to the inner jacket, allowing smooth extrusion without requiring complex separation mechanisms.
Solution Approach 2:
The friction layer is a thin, simple component (0.001-0.006 inches thick) that facilitates the extrusion process. It is a straightforward, inexpensive solution that performs its function during manufacturing without requiring complex systems or expensive materials.
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
The implementation of a high friction layer significantly improves the coupling between the outer jacket and the aramid yarn wrap, ensuring stable installation and reducing the likelihood of 'corkscrewing' failures, as demonstrated by tensile testing which shows acceptable coupling values exceeding 100 pounds and minimal slippage.
Implementation Method 1
the use of a friction layer between the aramid yarn wrap and the outer jacket prevents unwanted slippage of the outer jacket
Data Source
AI summary
Described are track-resistant all dielectric self-supporting (TR-ADSS) cables with improved cable jackets. A typical TR-ADSS optical fiber cable comprises an optical fiber sub-assembly, and a cable jacket system. The cable jacket system comprises an inner jacket, an aramid strength layer and an outer jacket. The improvement in the cable jacket system results from the addition of a friction layer between the aramid strength layer and the outer jacket. The friction layer prevents unwanted slippage of the outer jacket with respect to the inner portions of the cable.