Thermomechanical Mechanism for Delamination of Polymer Coatings From Optical Fibers

1997 ◽  
Vol 119 (2) ◽  
pp. 133-137 ◽  
Author(s):  
W. W. King ◽  
C. J. Aloisio
Keyword(s):  
Compressive Stress ◽  
Optical Fibers ◽  
Single Layer ◽  
Fiber Surface ◽  
Polymer Coatings ◽  
Layer System ◽  
External Disturbances ◽  
Hydrostatic Tension ◽  
Low Modulus ◽  
Radial Tension

Sometimes the polymer coating on an optical fiber is observed to have separated from the fiber over a small portion of the interface. Irregularities on the capstans and sheaves of draw, rewind, coloring, and cabling machines can initiate such delaminations. Subsequent growth would not be anticipated under the condition of radial compressive stress that might be expected for a coating shrinking over a relatively rigid fiber as the composite cools during manufacture. Compressive stress is indeed found at the interface when a single-layer coating is used. However, for a two-layer system, having a high-modulus secondary over a low-modulus primary (for improved protection against microbending), the different rates of thermal expansion can lead to radial tension at the silica/primary interface, and this tension can “drive” the growth of delaminations. A principal result of this study is that the analysis predicts the primary coating, although rubbery, to be approximately in a state of uniform hydrostatic tension. This tensile stress is of substantial magnitude because of constraints imposed by the relatively stiff secondary coating and by the fiber. The existence of significant radial tension at the fiber surface is consistent with experimental observations of induced delaminations, which are seen to grow long after cessation of external disturbances.

Discrete element method to model cracking for two layer systems

TAPPI Journal ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 101-108
Author(s):  
Daniel Varney ◽  
Douglas Bousfield
Keyword(s):  
Discrete Element Method ◽  
Flexural Modulus ◽  
Single Layer ◽  
Discrete Element ◽  
Flexural Stress ◽  
Layer System ◽  
Three Point Bending ◽  
Moving Force ◽  
Coating Layers ◽  
Element Method

Cracking at the fold is a serious issue for many grades of coated paper and coated board. Some recent work has suggested methods to minimize this problem by using two or more coating layers of different properties. A discrete element method (DEM) has been used to model deformation events for single layer coating systems such as in-plain and out-of-plain tension, three-point bending, and a novel moving force picking simulation, but nothing has been reported related to multiple coating layers. In this paper, a DEM model has been expanded to predict the three-point bending response of a two-layer system. The main factors evaluated include the use of different binder systems in each layer and the ratio of the bottom and top layer weights. As in the past, the properties of the binder and the binder concentration are input parameters. The model can predict crack formation that is a function of these two sets of factors. In addition, the model can predict the flexural modulus, the maximum flexural stress, and the strain-at-failure. The predictions are qualitatively compared with experimental results reported in the literature.

scholarly journals Characteristics of Oceanic Warm Cloud Layers within Multilevel Cloud Systems Derived by Satellite Measurements

Atmosphere ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 465 ◽  
Author(s):  
Yuhao Ding ◽  
Qi Liu ◽  
Ping Lao
Keyword(s):  
Double Layer ◽  
Lower Layer ◽  
Single Layer ◽  
Distribution Patterns ◽  
Radar Data ◽  
Multilayered Structures ◽  
Layer System ◽  
Cloud Systems ◽  
Warm Cloud ◽  
Double Layer System

Low-level warm clouds are a major component in multilayered cloud systems and they are generally hidden from the top-down view of satellites with passive measurements. This study conducts an investigation on oceanic warm clouds embedded in multilayered structures by using spaceborne radar data with fine vertical resolution. The occurrences of warm cloud overlapping and the geometric features of several kinds of warm cloud layers are examined. It is found that there are three main types of cloud systems that involve warm cloud layers, including warm single layer clouds, cold-warm double layer clouds, and warm-warm double layer clouds. The two types of double layer clouds account for 23% and in the double layer occurrences warm-warm double layer subsets contribute about 13%. The global distribution patterns of these three types differ from each other. Single-layer warm clouds and the lower warm clouds in the cold-warm double layer system they have nearly identical geometric parameters, while the upper and lower layer warm clouds in the warm-warm double layer system are distinct from the previous two forms of warm cloud layers. In contrast to the independence of the two cloud layers in cold-warm double layer system, the two kinds of warm cloud layers in the warm-warm double layer system may be coupled. The distance between the two layers in the warm-warm double layer system is weakly dependent on cloud thickness. Given the upper and lower cloud layer with moderate thickness of around 1 km, the cloudless gap reaches its maximum when exceeding 600 m. The cloudless gap decreases in thickness as the two cloud layers become even thinner or thicker.

In situ growth of Au–Ag bimetallic nanorings on optical fibers for enhanced plasmonic sensing

2020 ◽  
Vol 8 (22) ◽  
pp. 7552-7560 ◽  
Author(s):  
Se Shi ◽  
Anran Li ◽  
Renliang Huang ◽  
Jing Yu ◽  
Shuzhou Li ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Oxidation Resistance ◽  
Optical Fibers ◽  
Fiber Surface ◽  
Metal Deposition ◽  
In Situ Growth ◽  
Plasmonic Sensing

Au–Ag bimetallic nanorings were grown in situ on an optical fiber surface via bioinspired PDA, a synergetic GRR and metal deposition, which exhibited enhanced LSPR sensitivity and oxidation resistance.

Optical intensity-driven reversible photonic bandgaps in self-organized helical superstructures with handedness inversion

2017 ◽  
Vol 5 (15) ◽  
pp. 3678-3683 ◽  
Author(s):  
Jian Sun ◽  
Li Yu ◽  
Ling Wang ◽  
Chenyue Li ◽  
Zhou Yang ◽  
...  
Keyword(s):  
Single Layer ◽  
Optical Intensity ◽  
Layer System ◽  
Photonic Bandgaps ◽  
Self Organized ◽  
System P ◽  
Bandwidth Broadening

Optical intensity-driven self-organized helical superstructures were found to exhibit reversibly photodynamical photonic bandgaps in wavelength shifting, bandwidth broadening and reflectance enhancing in single-layer system.

Selective withdrawal from a stably stratified fluid

1968 ◽  
Vol 32 (2) ◽  
pp. 209-223 ◽  
Author(s):  
I. R. Wood
Keyword(s):  
Single Layer ◽  
Layered System ◽  
Volume Discharge ◽  
Layer System ◽  
Minimum Width ◽  
Theoretical Predictions ◽  
Small Rise ◽  
Self Similar ◽  
The One ◽  
Dead Water

In this paper a reservoir connected through a horizontal contraction to a channel is considered. Both the reservoir and the channel are considered to contain a stable multi-layered system of fluids. The conditions under which there is a flow in only one layer, and the depth in this flowing layer decreases continuously from its depth in the reservoir to its depth in the channel, give the maximum discharge that can be obtained with a flow only from this single layer. For this case the volume discharge calculations are carried out at a single section (the section of minimum width). Where there are velocities in only two layers and the depth in each of these layers decreases continuously from their depths in the reservoir to their depths in the channel, the theory involves computations at two sections in the flow. These are the section of minimum width and a section upstream of the position of minimum width (the virtual point of control). For this flow it is shown that the solution is the one in which the velocity and density distributions are self similar and that the depths of the layers at the point of maximum contraction are two-thirds of those far upstream. It is then shown that for any stable continuous or discrete density stratification in the reservoir a self similar solution will satisfy the conditions for the depths of the flowing layers to decrease smoothly from the reservoir to downstream of the contraction. Again the ratio of the depth at the contraction to that far upstream is two-thirds.When there is a very large density difference between the fluid in the lower dead water and that in the lowest flowing streamline then this streamline becomes horizontal and may be considered as a frictionless bed. The flow when the bed is not horizontal but where there is a small rise in the channel at the position of maximum contraction is considered for the case where two discrete layers flow under a volume of dead water. In this case the velocity and density profiles are not self similar.Experiments have been carried out with a contraction in a flume for the withdrawal of two discrete layers from a three layer system and the withdrawal from a fluid with a linear density gradient. In both cases the reservoir and channel bed and hence the lowest streamline was effectively horizontal. These experiments confirmed the theoretical predictions.

Specialty High Performance Coatings for Optical Fiber Applications via Perfluorocyclobutyl (PFCB) Aryl Ether Polymers

2007 ◽  
Vol 1030 ◽  
Author(s):  
Stephen M. Budy ◽  
Scott T. Iacono ◽  
Wade Hawkins ◽  
Paul Foy ◽  
John Ballato ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
High Performance ◽  
Polymer Coatings ◽  
Aryl Ether ◽  
Molecular Weights ◽  
Higher Temperature ◽  
Optical Applications ◽  
Optical Fiber Applications ◽  
Fiber Coatings

AbstractThere is a growing need for optical fiber coatings that can sustain higher temperatures than present materials permit. To date, polyimides are used predominantly but they generally are difficult to process and usually require multiple depositions to achieve the desired film thickness. Perfluorocyclobutyl (PFCB) aryl ether polymers have demonstrated much success as processable and amorphous fluoropolymers,[1] with particular emphasis on high performance optical applications.[2] This work discusses recent efforts into perfluorocyclobutyl aryl ether polymer-based optical fiber coatings.[3] A series of silica-based optical fibers were drawn with differing PFCB polymer coatings compositions and molecular weights on a Heathway draw tower. Results include a more than doubled usage temperature of coating (decomposition temperatures (Td) in nitrogen and air were above 450 °C) without affecting fiber mechanical properties and comparable isothermal stability to conventional coatings, except with a >150 °C higher temperature. Preliminary results of the first successful coating of optical fibers by PFCB polymers will be presented herein, as well as future endeavors.

Thermal Radiative Properties of a Semitransparent Fiber Coated With a Thin Absorbing Film

2006 ◽  
Vol 129 (6) ◽  
pp. 763-767 ◽  
Author(s):  
Weixue Tian ◽  
Wei Huang ◽  
Wilson K. S. Chiu
Keyword(s):  
Thin Film ◽  
Optical Fibers ◽  
Fiber Surface ◽  
Chemical Vapor ◽  
Fused Silica ◽  
Radiative Properties ◽  
Thermal Radiative Properties ◽  
Proposed Model ◽  
Transport Analysis ◽  
Fiber Radius

This study presents the hemispherical model to predict the hemispherical total thermal radiative properties of a fiber coated with a thin film. The fiber is composed of semi-transparent media, such as fused silica. The film is made of strong absorbing media with thickness on the order of tens of nanometers. The film is assumed to be “locally flat” at the point of incidence for radiative transfer analysis because the thickness of the film is much less than the fiber radius. Wave optics is employed to calculate the reflectance and transmittance of the thin film while the ray tracing method is used for radiative transport analysis of the fiber. Effects of film and fiber substrate optical properties, film thickness and temperature on predicted thermal radiative properties are investigated. One of the applications of the proposed model is for studying the chemical vapor deposition of hermetic coatings on optical fibers, in which the thermal radiative properties of the fiber–film system heavily influence the fiber surface temperature and chemical reaction rate.

scholarly journals Mass transport in water waves over a thin layer of soft viscoelastic mud

2007 ◽  
Vol 573 ◽  
pp. 105-130 ◽  
Author(s):  
CHIU-ON NG ◽  
XUEYAN ZHANG
Keyword(s):  
Mass Transport ◽  
Thin Layer ◽  
Water Waves ◽  
Stokes Equations ◽  
Steady Motion ◽  
Single Layer ◽  
Viscoelastic Layer ◽  
Layer System ◽  
Overlying Water ◽  
Viscoelastic Parameter

A theory is presented for the mass transport induced by a small-amplitude progressive wave propagating in water over a thin layer of viscoelastic mud modelled as a Voigt medium. Based on a sharp contrast in length scales near the bed, the boundary-layer approximation is applied to the Navier–Stokes equations in Lagrangian form, which are then solved for the first-order oscillatory motions in the mud and the near-bed water layers. On extending the analysis to second order for the mass transport, it is pointed out that it is inappropriate, as was done in previous studies, to apply the complex viscoelastic parameter to a higher-order analysis, and also to suppose that a Voigt body can undergo continuous steady motion. In fact, the time-mean motion of a Voigt body is only transient, and will stop after a time scale given by the ratio of the viscosity to the shear modulus. Once the mud has attained its steady deformation, the mass transport in the overlying water column can be found as if it were a single-layer system. It is found that the near-bed mass transport has non-trivial dependence on the mud depth and elasticity, which control the occurrence of resonance. Even when the resonance is considerably damped by viscosity, the mass transport in water over a viscoelastic layer can be dramatically different, in terms of magnitude and direction, from that over a rigid bed.

Surface Treatments to Enhance the Sensitivity of Plastic Optical Fiber Based Accelerometers

2013 ◽  
Vol 543 ◽  
pp. 297-301 ◽  
Author(s):  
Alberto Vallan ◽  
Sabrina Grassini ◽  
Guido Perrone
Keyword(s):  
Optical Fibers ◽  
Light Propagation ◽  
Low Cost ◽  
Polymer Surface ◽  
Fiber Surface ◽  
Industrial Applications ◽  
Propagation Loss ◽  
Test Facility ◽  
Cantilever Bending ◽  
Physical Treatments

The paper presents an all-fiber accelerometer that uses plastic optical fibers and discusses the enhancement of its sensitivity through physical treatments on the polymer surface to modify the light propagation characteristics. Given the target of being low-cost and compact, the accelerometer exploits the variation of propagation loss induced by the deformations of a miniaturized cantilever on which the fiber is fixed. This simple setup, however, does not exhibit a sufficient sensitivity unless the fiber surface is properly treated in order to enhance the loss dependence with the cantilever bending. Two approaches are compared, namely plasma micro-and nanotexturing and laser localized ablations. Several prototypes of accelerometers have been fabricated using various types of plastic fibers and characterized using a vibration test facility. Preliminary results show that both techniques are effective and can produce similar results, although accelerometer made by laser localized ablation may be more suitable for industrial applications, like the monitoring of vibrations due to moving parts of machines.

scholarly journals Optimisation of ballistic protection systems based on impact test/simulation correlation

2021 ◽  
Vol 250 ◽  
pp. 04001
Author(s):  
Yohan Cosquer ◽  
Patrice Longère ◽  
Olivier Pantalé ◽  
Claude Gailhac
Keyword(s):  
Numerical Model ◽  
Total Mass ◽  
Impact Test ◽  
Single Layer ◽  
Test Results ◽  
Protective Capacity ◽  
Layer System ◽  
Residual Velocity ◽  
Ballistic Protection ◽  
Protection Systems

The complexity of ballistic protections increases with their efficiency. On this basis, an exclusively empirical approach is not adapted to optimise complex protection systems and the resort to numerical simulations is preferred if not mandatory. The present study proposes a methodology aiming at optimising complex multi-layer ballistic armours based on an experimental-numerical correlation. A multi-layer system is taken as example. A numerical model is first calibrated according to impact-on-monolithic-target test results. Once the model is validated, an optimisation process considering multi-layer configurations involving a sharp-nosed threat modifies the plates’ thicknesses in order to minimise the total mass while ensuring the system’s protective capacity in terms of residual velocity. The optimisation process shows that a single layer system is more efficient than a multi-layer one in the studied case.

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