Multi-Layer Optical Fibre Cable Tubes for Inner-Layer Crush Resistance
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Solution Overview
Problem
Current optical fiber cables with multi-layered buffer tubes face issues such as crushing of innermost layers due to higher stresses, overdesigning, and the use of different materials in inner and outer layers leading to inefficiencies.
Innovation Solution
The optical fiber cable design incorporates tubes with varying Young's modulus, with inner layers having higher modulus than outer layers, and uses the same material but different grades to enhance stress distribution and reduce overdesigning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multi-layered buffer tubes are used with same material in inner and outer layers, then cable structure is simplified, but innermost layer tubes are crushed due to higher stresses
Solution Approach 1:
The patent applies local quality by using buffer tubes made of the same material across all layers but assigning different Young's modulus values to different layers. Specifically, inner layer tubes have a higher Young's modulus (e.g., 1.0-2.0 GPa) compared to outer layer tubes (e.g., 0.5-1.5 GPa), allowing each layer to be optimized for its specific stress conditions while maintaining material consistency throughout the cable structure.
2Strength
If different materials are used for inner and outer layer buffer tubes, then crush resistance of inner layers is improved, but overdesigning occurs and material costs increase
Solution Approach 1:
The patent implements parameter changes by maintaining the same base material composition for all buffer tubes but varying the Young's modulus parameter across layers through different material grades or formulations. This allows optimization of mechanical properties for each layer's specific stress environment without requiring completely different materials, thereby avoiding overdesigning and reducing overall material costs.
3Strength
If buffer tubes in innermost layer have high Young's modulus, then crush resistance is improved, but cable flexibility is reduced
Solution Approach 1:
The patent applies local quality by creating a gradient of Young's modulus values across different layers, with higher modulus in inner layers for crush resistance and lower modulus in outer layers for flexibility. This spatial variation in material properties allows the cable to simultaneously achieve both crush resistance and flexibility without compromising either property.
Data Source
AI summary
The present invention relates to an optical fiber cable (100, 200, 300) comprising a plurality of tubes (104) and a sheath (114) encapsulating the plurality of tubes (104) with a plurality of optical fibers (106). At least one tube of the plurality of tubes (104) has young's modulus that is different from other tubes and the young's modulus that is at least 30% more than young's modulus of the other tubes. In particular, the plurality of tubes (104) is arranged in an innermost layer (108) and an outermost layer (110). Additionally, young's modulus of the innermost layer (108) is greater than young's modulus of the outermost layer (110). Further, the diameter of the central strength member (102) is in a range of 1.5 millimetres to 6 millimetres.