Fiber Optic Drop Cable Anti-Buckling Design
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Solution Overview
Problem
Existing fiber optic drop cables face challenges in flexibility and access to optical fibers due to rigid strength members like glass-reinforced plastic or steel rods, which limit flexibility and make it difficult to remove sections during installation, while also needing to withstand environmental factors and axial loading.
Innovation Solution
A fiber optic cable design featuring a subunit with a first reinforcement material and an outer portion with a second reinforcement material of fiberglass yarn, where the fiberglass yarn is constrained by the outer jacket to provide anti-buckling support and mitigate temperature-induced shrinkage, while allowing for improved flexibility and easy access by using non-rigid materials and strategically positioned reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid strength members (glass-reinforced plastic or steel rods) are used to provide tensile strength and anti-buckling support, then the cable can withstand environmental factors and axial loading, but the flexibility of the cable is limited and it becomes difficult to cut through and remove sections during installation
Solution Approach 1:
The patent changes the physical state and mechanical properties of the strength members by using flexible fiberglass yarn instead of rigid rods. The fiberglass yarn can be constrained in different configurations (e.g., wrapped around the cable, positioned in grooves) to provide anti-buckling support while maintaining cable flexibility. This parameter change resolves the contradiction by achieving both strength and flexibility.
Solution Approach 2:
The patent employs composite construction by combining fiberglass yarn with the cable jacket and buffer tube materials. The fiberglass yarn is embedded within or alongside the polymer materials, creating a composite structure that provides both the tensile strength needed for outdoor use and the flexibility required for installation. This composite approach allows the cable to meet both contradictory requirements.
2Length of moving object
If the cable is designed to be narrow to pass through small ducts, then it can be installed in fiber-to-the-home applications, but it becomes more difficult to provide sufficient structural support and protection against environmental factors
Solution Approach 1:
The patent uses flexible polymer jackets (outer jacket and buffer tube) that provide environmental protection while maintaining a narrow cable diameter. These flexible shells conform to the compact structure needed for small duct installation while still providing protection against moisture, UV, and mechanical damage. The flexibility of these shells allows the cable to bend and pass through tight spaces.
Solution Approach 2:
The patent employs composite materials combining fiberglass yarn with polymer jackets to achieve high strength-to-diameter ratio. The fiberglass reinforcement is integrated into the narrow cable structure, providing the necessary structural support and environmental resistance without significantly increasing the cable outer diameter. This allows the cable to meet both the size constraint for duct installation and the strength requirement for outdoor use.
3Reliability
If reinforcement material is added to provide anti-buckling support, then the cable can withstand axial loading and temperature-induced shrinkage, but the cable becomes less flexible and more difficult to install
Solution Approach 1:
The patent changes the configuration and positioning parameters of the fiberglass yarn to optimize both anti-buckling performance and flexibility. The yarn can be wrapped around the cable at specific intervals, positioned in longitudinal grooves, or arranged in helical patterns. These parameter variations allow the reinforcement to provide reliable anti-buckling support while minimizing impact on cable flexibility and ease of installation.
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 cable achieves enhanced flexibility and maneuverability, allowing it to pass through small ducts and withstand environmental conditions without buckling, while maintaining anti-buckling support and easy access to the optical fibers for installation and maintenance.
Implementation Method 1
hoop stress applied to the fiberglass yarn by the outdoor jacket axially constrains the fiberglass yarn such that the fiber glass yarn is positioned and oriented to provide anti-buckling support to the fiber optic cable and mitigate effects on the optical fiber of jacket shrinkage due to low temperatures
Implementation Method 2
the optical fiber and the subunit jacket are coupled to one another by way of frictional contact or adhesion with the first reinforcement material
Implementation Method 3
the optical fiber and the subunit jacket are coupled to one another by way of frictional contact or adhesion with the first reinforcement material
Data Source
AI summary
A fiber optic cable includes a subunit and an outer portion. The subunit includes a subunit jacket defining a passageway interior thereto, an optical fiber extending through the passageway, and a first reinforcement material constraining the optical fiber within the subunit jacket such that the optical fiber and the subunit jacket are coupled to one another by way of the first reinforcement material. The outer portion of the fiber optic cable includes an outer jacket defining an outer periphery of the cable and a second reinforcement material between the outer jacket and the subunit jacket. The second reinforcement material includes fiberglass yarn, and hoop stress applied to the fiberglass yarn by the outer jacket constrains the fiberglass yarn such that it is positioned and oriented to provide anti-buckling support to the fiber optic cable and mitigate effects on the optical fiber of jacket shrinkage due to low temperatures.