Fiber Optic Cable Diagonal Strength Members Crush Resistance
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Solution Overview
Problem
Fiber optic cables used in communications networks face challenges in withstanding crush loads and maintaining optical performance during installation, particularly due to deformation caused by pressure clamps, and they require large storage spaces for excess length, complicating installation and manufacturing.
Innovation Solution
A fiber optic cable design featuring optical fibers surrounded by elongate strength components and a polymeric jacket with a medial height less than the end height, allowing for a small cross-sectional area and resistance to crush loads, eliminating the need for buffer tubes, and enabling efficient slack storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fiber optic cables with buffer tubes are used, then the fiber is protected from deformation, but the cable has large cross-sectional area and requires large storage spaces
Solution Approach 1:
The invention removes the buffer tube from the cable structure, extracting the element that causes large cross-sectional area. The fiber is directly surrounded by strength components and jacket, eliminating the need for buffer tubes while maintaining fiber protection through the redesigned structure with elongate strength components positioned at diagonals.
Solution Approach 2:
The invention uses composite material structure combining optical fiber, elongate strength components (such as aramid yarns), and polymeric jacket. This composite structure provides both mechanical strength and fiber protection in a compact configuration, achieving high strength-to-area ratio.
2Force
If pressure clamps are used to secure the cable, then the cable is held firmly, but the clamp force deforms the cable and damages the fiber
Solution Approach 1:
The invention positions the elongate strength components at diagonals of the cable cross-section, creating an asymmetric arrangement that provides superior resistance to crush loads from pressure clamps. This diagonal positioning allows the strength components to effectively counteract the clamping force without deforming the fiber, as the strength members are oriented to bear the compressive loads.
Solution Approach 2:
The elongate strength components are positioned beforehand to provide cushioning protection against pressure clamp deformation. The strength members are strategically placed at diagonals to intercept and absorb the clamping force before it can transmit to the fiber, preventing deformation and maintaining optical performance.
3Reliability
If the cable has large cross-sectional area, then the fiber is well protected, but the storage requirements and manufacturing costs increase
Solution Approach 1:
The invention changes the geometric parameters of the cable structure by positioning strength components at diagonals and using a polymeric jacket with specific height ratios (medial height less than end height). This parameter optimization achieves effective fiber protection with minimized cross-sectional area, reducing storage requirements and manufacturing costs.
Solution Approach 2:
The invention transitions from a traditional circular or symmetric cable cross-section to a diagonally-oriented strength component arrangement. This dimensional reconfiguration allows the strength members to provide maximum protection along diagonal axes while minimizing the overall cross-sectional area, achieving efficient space utilization.
4Ease of manufacture
If the cable design is simplified without buffer tubes, then manufacturing costs are reduced, but the fiber may be more susceptible to damage
Solution Approach 1:
The invention creates a composite structure where elongate strength components (such as aramid yarns) and polymeric jacket work together to protect the fiber. This composite design eliminates buffer tubes, simplifying manufacturing and reducing costs, while the synergistic combination of strength members and jacket material provides adequate fiber protection.
Solution Approach 2:
The polymeric jacket in the invention serves multiple functions: it provides mechanical protection, environmental barrier, and structural integrity. Combined with the diagonally positioned strength components, the jacket creates a multi-functional protective system that replaces the traditional buffer tube functions while reducing overall complexity and manufacturing cost.
Data Source
AI summary
A fiber optic cable includes an optical fiber, strength components disposed on opposite sides of the optical fiber, and a polymeric cable jacket. The optical fiber includes a glass core, a glass cladding, and a polymer coating. The cable jacket surrounds the optical fiber and the strength components. Further, the cable jacket is tightly drawn onto the optical fiber, where excess fiber length of the optical fiber is such that positive strain is present in the optical fiber at room temperature (25° C.).