Fiber Optic Cable Off-Center GRP Strength Members
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Solution Overview
Problem
Existing mid and high fiber count loose tube fiber optic cables face challenges with cold temperature resistance, mechanical strength, flexibility, and fire safety due to the use of polymer jacketed Central Strength Members (CSMs), which lead to excessive attenuation, large diameters, and limited bend radius ratings.
Innovation Solution
The use of two or more off-center, smaller non-polymer jacketed Glass Reinforced Polymers (GRPs) with a novel arrangement of buffer tubes and filler materials to create a more flexible and crush-resistant cable core, reducing cold temperature shrinkage and improving mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymer jacketed Central Strength Members (CSMs) are used, then mechanical strength is improved, but cold temperature resistance deteriorates due to excessive attenuation
Solution Approach 1:
The patent removes the polymer jacket from the Central Strength Member (CSM), extracting the problematic polymer material that causes excessive contraction in cold temperatures. The CSM is left as bare glass-reinforced polymer, eliminating the source of cold temperature-induced attenuation while maintaining the core strength function.
Solution Approach 2:
The patent uses composite materials by combining glass fibers with polymer binder in the CSM to create a material that provides both mechanical strength and thermal stability. The glass-reinforced polymer structure offers high tensile strength while minimizing thermal contraction compared to pure polymer materials.
2Strength
If polymer jacketed CSMs are used, then mechanical strength is improved, but flexibility deteriorates due to large diameter and limited bend radius
Solution Approach 1:
By removing the polymer jacket from the CSM, the patent reduces the overall cable diameter and eliminates the rigid structure that limits bending. This extraction allows the cable to achieve smaller bend radii and improved flexibility while the bare CSM still provides necessary mechanical strength through its glass-reinforced structure.
Solution Approach 2:
The patent employs a loose tube design where optical fibers are contained in flexible polymer tubes rather than being directly bound to a rigid CSM. This flexible tube structure allows the cable to bend more easily while the CSM provides underlying strength support.
3Strength
If polymer jacketed CSMs are used, then mechanical strength is improved, but fire safety deteriorates
Solution Approach 1:
The patent extracts the polymer jacket material from the CSM, removing the combustible material that contributes to fire hazards. By using a bare or minimally jacketed CSM with fire-resistant glass-reinforced polymer, the cable generates less smoke and toxic fumes during fire conditions while maintaining structural integrity.
Solution Approach 2:
The glass-reinforced polymer material in the CSM provides inherent fire resistance and low smoke emission properties, creating a more fire-safe environment. The glass fibers do not combust and release minimal toxic gases, improving the cable's fire safety classification.
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 configuration enhances cold temperature resistance, flexibility, and crush resistance, while maintaining smaller diameters and improved handling and storage capabilities, with reduced signal attenuation and enhanced fire safety.
Implementation Method 1
UV coated optical fiber(s) loosely contained inside each buffer tube
Implementation Method 2
GRP (Glass Reinforced Polymer) provides various mechanical advantages to the cable including longitudinal strength
Implementation Method 3
the fibers have the ability to bend/move (such as into a sinusoidal shape or minimally helical shape) along the length of the cable, accumulating as the cable (jacket and tubes) contracts over cold temperature extremes
Data Source
AI summary
A multi-tube optical fiber cable has a core with a first set of one or more optical fiber tubes, each having one or more optical fibers loosely arranged therein. The first set of tubes is constructed of a polymer having a low Young's constant modulus. The core also includes at least two strength members with a first binder arranged around the first set of optical fiber tubes and the strength members, where the first binder is substantially flat in shape such that there is no deformation of the first set of tubes, and where the strength members are offset from a central axis of the cable. The cable maintains a second set of a plurality of optical fiber tubes, each having one or more optical fibers loosely arranged therein, arranged around the outer circumference of the core.