Optical Fiber Cable Assembly Axial Load Balancing

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Solution Overview

Problem

Conventional optical communication cable assemblies either isolate optical fibers from axial loading or use excess fiber length to ensure strength elements bear the load, leading to inefficiencies and difficulties in detecting overloading before optical connector failure.

Innovation Solution

The optical communication cable assembly balances axial loading between optical fibers and tensile strength elements by ensuring both components experience the load, with a ratio of axial rigidity that limits subunit compression and provides a visible indication of overloading before connector failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical fibers are isolated from axial loading using conventional designs, then optical connector failure is prevented, but the cable assembly cannot detect overloading conditions before failure occurs

Engineering Contradiction:
Improveoptical connector failure preventionVSAvoidoverloading detection
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent implements feedback by allowing optical fibers to experience axial loading and transfer this mechanical stress to the optical connectors. This creates a visible indication system where connector displacement or damage serves as feedback signaling overloading conditions, enabling detection while maintaining reliability through controlled load transfer mechanisms.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary mechanism where optical fibers act as mediators between the tensile strength elements and optical connectors. The fibers transmit a portion of the axial load to the connectors, creating an intermediate load path that enables detection without directly exposing connectors to full loading forces.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If excess fiber length is used to ensure strength elements bear the load, then load bearing capacity is improved, but cable diameter and complexity increase

Engineering Contradiction:
Improveload bearing capacityVSAvoidcable structure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent changes the parameter of fiber length from excessive to optimized, and modifies the axial rigidity ratio between tensile strength elements and optical fibers. By adjusting these parameters, the system achieves adequate load bearing capacity without requiring excess fiber length, thereby reducing cable complexity and diameter.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by creating different axial rigidity characteristics in different parts of the cable structure. The tensile strength elements and optical fibers have specifically engineered axial rigidity ratios that enable differentiated load sharing, allowing efficient load bearing without uniform excess length throughout the cable.

Inventive Principle:
Principle #3Local quality

3Reliability

If optical fibers experience no axial loading, then connector protection is improved, but the ability to provide visible indication of overloading is lost

Engineering Contradiction:
Improveconnector protectionVSAvoidoverloading indication capability
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies partial action by allowing optical fibers to experience a controlled portion of the axial load rather than isolating them completely. This partial load exposure provides sufficient mechanical indication to optical connectors for overloading detection while maintaining adequate protection through the load-sharing arrangement between strength elements and fibers.

Inventive Principle:
Principle #16Partial or excessive action

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 design effectively distributes axial loading, preventing over-compression and connector failure while reducing the need for excess fiber length and outer cable diameter, allowing for early detection of excessive loading through visible subunit compression.

Implementation Method 1

a spring located between the ferrule and the body, the spring having a spring force representative of the force needed to cause a maximum allowed compression of the spring

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 2

A ratio of the axial rigidity of the second tensile strength element to the axial rigidity of the optical fibers of each subunit is such that, when a decrease in length of the subunit end portion under the axial loading is between 0.1% and 2.5%, the portion of the axial load experienced by the optical fibers of the subunit is greater than zero and is less than the spring force

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3521880B1Optical fiber cable assembly
Publication Date: 2020.09.09 CORNING OPTICAL COMMUNICATIONS LLC
  • EP3521880B1 patent drawingFigure 1~2
  • EP3521880B1 patent drawingFigure 3~5
  • EP3521880B1 patent drawingFigure 6~8

AI summary

An optical cable assembly is provided. The cable assembly includes a plurality of subunits surrounded by an outer cable jacket, a furcation unit and optical connectors coupled to the end of each of the subunits. Each of the subunits includes an inner jacket, a plurality of optical fibers; and a tensile strength element. The first tensile strength element and the inner jackets of each subunits are coupled to the furcation unit, and the optical fibers and tensile strength elements of each subunit extend through the furcation unit without being coupled to the furcation unit. The subunit tensile strength element and optical fibers of each subunit are balanced such that both experience axial loading applied to the assembly and, under various loading conditions, the compression of the subunits is controlled and/or the axial loading of the optical fibers is limited to allow proper function of the optical connector.