Optical Fiber Cable Fibrous Fillings Stability
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Solution Overview
Problem
In optical fiber cables, the rigidity of optical fiber units leads to untwisting forces that cause movement within the sheath, disrupting the twisted state and increasing untwisting forces, especially when multiple units are twisted together, resulting in instability and potential transmission loss.
Innovation Solution
The optical fiber cable design includes a core with optical fiber units and fibrous fillings extending in the longitudinal direction, wrapped by a tube and embedded tension members within a sheath, with specific cross-sectional area ratios to limit movement and absorb external forces, using materials like polyolefin resin and metal wires to maintain the twisted state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If optical fiber units are twisted together to form a compact cable structure, then the cable space utilization is improved, but the rigidity of optical fiber units generates untwisting forces that cause movement and disrupt the twisted state
Solution Approach 1:
A filling material is introduced as an intermediary substance between the optical fiber units. This filling material has specific mechanical properties that allow it to resist the untwisting forces generated by the rigidity of optical fiber units, thereby maintaining the twisted state while enabling compact cable structure. The filling acts as a mediator that balances the competing requirements of space utilization and structural stability.
Solution Approach 2:
The invention controls the physical parameters of the filling material, specifically its cross-sectional area ratios relative to optical fibers and sheath inner space. By adjusting these parameters within specific ranges, the filling material can effectively counterbalance the untwisting forces while maintaining the compact twisted configuration of optical fiber units.
2Ease of operation
If the optical fiber units are moved by untwisting forces, then the twisted state is released, but transmission loss increases and cable performance deteriorates
Solution Approach 1:
The filling material serves as a stabilizing intermediary that prevents excessive movement of optical fiber units caused by untwisting forces. By resisting these forces, the filling material maintains the twisted state and prevents transmission loss, while still allowing the cable to maintain necessary flexibility for installation and operation.
Solution Approach 2:
By controlling the cross-sectional area parameters of the filling material relative to the optical fibers and sheath space, the invention optimizes the balance between cable flexibility and transmission stability. The specific parameter ranges ensure that the filling provides sufficient resistance to untwisting forces without overly constraining cable movement.
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 effectively limits the movement of optical fiber units, reduces transmission loss, and enhances shock absorption, maintaining the twisted state even under vibration and temperature changes by adjusting the filling amounts and elastic modulus of the fibrous fillings.
Implementation Method 1
a shock absorbing material disposed at the center of the cable... the shock absorbing material absorbs an external force applied to the optical fiber cable
Implementation Method 2
a pair of tension members that are embedded in the sheath so as to interpose the core therebetween
Data Source
Figure 1
Figure 2
AI summary
The present invention provides an optical fiber cable including a core including a plurality of optical fiber units each having a plurality of optical fibers; fibrous fillings extending in a longitudinal direction in which the optical fiber units extend; and a wrapping tube enclosing the plurality of optical fiber units and the fillings; a sheath that accommodates the core therein; and a pair of tension members that are embedded in the sheath so as to interpose the core therebetween, and in a transverse cross-sectional view, when a total value of cross-sectional areas of the plurality of optical fibers is Sf, a total value of cross-sectional areas of the fillings is Sb, a cross-sectional area of an inner space of the sheath is Sc, and a cross-sectional area of the wrapping tube is Sw, and it is established that 0.16 ≤ Sb/Sf ≤ 0.25 and 0.10 ≤ Sb/(Sc-Sw) ≤ 0.15.