Optical Fiber Capstan with Compliant Polyurethane Gel Surface
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Solution Overview
Problem
The existing screen testing processes for optical fibers often result in coating failures and increased manufacturing costs due to mismatched compressive and shear stresses between original and recoated sections of fibers, leading to cohesive and adhesive failures at splice joints.
Innovation Solution
An integrated capstan with a fiber-engaging material having a controlled hardness range of 40 Shore 00 to 70 Shore 00, typically a resilient polyurethane gel or UV-cured aliphatic urethane diacrylate compounds, is used to minimize stress transfer during fiber processing and testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a hard capstan surface is used to apply compressive load during screen testing, then the tensile stress can be effectively applied to the fiber, but additional stresses are imparted to the coatings causing failure or defect formation
Solution Approach 1:
A compliant layer is introduced as an intermediary between the hard capstan surface and the optical fiber. This layer has a hardness of 40-70 Shore 00, which is softer than traditional capstan surfaces. The compliant layer acts as a stress-distributing mediator that reduces peak stresses on the fiber coatings while still enabling effective tensile load application during screen testing
Solution Approach 2:
The hardness parameter of the capstan surface is changed from traditional hard materials to a compliant material with hardness specifically controlled in the range of 40-70 Shore 00. This parameter change allows the surface to deform slightly under load, distributing stresses more evenly across the fiber coating and preventing stress concentration that leads to coating failure
2Object-affected harmful factors
If a compliant fiber-engaging material is used to reduce stress on coatings, then coating failure is reduced, but the ability to effectively apply tensile stress for screen testing may be compromised
Solution Approach 1:
The hardness of the fiber-engaging material is optimized to a specific range of 40-70 Shore 00. This parameter range was determined to provide the optimal balance: soft enough to comply with fiber coatings and reduce stress concentration, yet firm enough to effectively transmit tensile loads during screen testing. The material is engineered to have appropriate elastic modulus and compressive strength within this hardness range
Solution Approach 2:
The capstan surface is constructed as a composite structure combining a hard substrate with a compliant fiber-engaging layer. The substrate provides structural support and load-bearing capacity, while the compliant layer (hardness 40-70 Shore 00) provides stress-distributing contact with the fiber. This composite approach enables simultaneous achievement of effective force application and reduced coating stress
3Productivity
If traditional belted capstan assemblies are used for screen testing, then production throughput is maintained, but splice joint damage occurs due to compliance mismatch between original and recoat sections
Solution Approach 1:
The compliance parameter of the capstan surface is changed by using material with hardness 40-70 Shore 00, which is softer and more compliant than traditional capstan surfaces. This compliance change allows the capstan to accommodate the differential deformation between low-modulus primary coating and high-modulus recoat sections, reducing shear stress at splice joints while maintaining continuous production throughput
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 solution reduces compressive and shear stresses on optical fibers, thereby decreasing coating failure rates and manufacturing costs by providing a flexible interface that absorbs stresses, preventing damage to fiber coatings and splice junctions.
Implementation Method 1
The fiber-engaging material having a hardness in the range from 40 Shore 00 to 70 Shore 00 minimizes transfer of stress to the fiber
Implementation Method 2
a resilient material... provides a flexible interface that absorbs stresses
Data Source
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AI summary
An integrated capstan for use in fiber processing and testing apparatus. The integrated capstan features a fiber-engaging material that provides a contact surface for fibers. The hardness of the contact surface is controlled to minimize transfer of stress to the fibers to prevent damage to fiber coatings or fiber splice junctions during conveyance or screen testing of fibers during production. The fiber-engaging material includes a resilient material and an optional capping layer. The resilient material may be a lightly crosslinked polyurethane gel. Capping layers include polymers formed by UV curing of aliphatic urethane diacrylate compounds or moisture curing of diisocyanate compounds.