Thermal stresses in tightly jacketed double‐coated optical fibers at low temperature

1994 ◽  
Vol 76 (12) ◽  
pp. 7695-7703 ◽  
Author(s):  
Sham‐Tsong Shiue
Keyword(s):  
Low Temperature ◽  
Optical Fibers ◽  
Thermal Stresses

Thermal stresses in carbon-coated optical fibers at low temperature

1997 ◽  
Vol 12 (9) ◽  
pp. 2493-2498 ◽  
Author(s):  
Sham-Tsong Shiue ◽  
Wen-Hao Lee
Keyword(s):  
Thermal Stress ◽  
Low Temperature ◽  
Glass Fiber ◽  
Young’S Modulus ◽  
Optical Fibers ◽  
Poisson’S Ratio ◽  
Carbon Coating ◽  
Thermal Stresses ◽  
Poisson's Ratio ◽  
Carbon Coated

The thermal stresses in carbon-coated optical fibers at low temperature have been analyzed. The thermally induced lateral pressure in the glass fiber would produce microbending loss. In order to minimize such a microbending loss, the thickness, Young's modulus, and Poisson's ratio of the carbon coating should be decreased. On the other hand, the maximum thermal stress is the tangential stress in the carbon coating that occurs at the interface of the carbon coating and glass fiber. It was experimentally observed that if the maximum thermal stress is larger than the tensile strength of the carbon coating, the carbon coating will be broken along the axial direction. In order to minimize such a maximum thermal stress, the thickness of the carbon coating should be increased, but Young's modulus, thermal expansion coefficient, and Poisson's ratio of the carbon coating should be decreased. Finally, an optimal selection of the carbon coating for optical fiber is discussed.

Thermal stresses in double‐coated optical fibers at low temperature

1992 ◽  
Vol 72 (1) ◽  
pp. 18-23 ◽  
Author(s):  
Sham‐Tsong Shiue ◽  
Sanboh Lee
Keyword(s):  
Low Temperature ◽  
Optical Fibers ◽  
Thermal Stresses

Behaviour of recycled asphalt pavements at low temperatures

1991 ◽  
Vol 18 (3) ◽  
pp. 428-435 ◽  
Author(s):  
M. Sargious ◽  
N. Mushule
Keyword(s):  
Finite Element ◽  
Low Temperature ◽  
Thermal Stresses ◽  
Asphalt Pavements ◽  
Recycled Asphalt ◽  
Expected Performance ◽  
Different Types ◽  
Low Temperature Cracking ◽  
Proper Comparison ◽  
Better Than

This paper summarizes the results of a study conducted to evaluate the behaviour of recycled asphalt pavements with respect to low-temperature cracking. For this purpose, a recycled mix consisting of 45.2% reclaimed materials and 54.8% virgin materials as well as a virgin control mix were used in the research program. In the design of both mixes, their initial properties were kept as close as possible to each other to allow for a proper comparison between recycled and virgin asphalt pavements. Using mix properties that were determined experimentally in the laboratory, thermal stresses resulted from drop in temperature and the expected cracking temperatures were determined for both mixes. An experimental analysis based on laboratory tests that consider the pavement properties only as well as a more complete theoretical analysis based on a finite element computer program known as FETAB were included in this study. The program incorporates subgrade parameters, as well as pavement properties and thickness. Using these variables as inputs to the program, the expected performance of recycled and virgin asphalt pavements of various thicknesses and resting on different types of subgrade, with respect to low-temperature cracking, was studied. The results of the study indicated that recycled asphalt pavements would perform better than virgin asphalt pavements of similar initial properties. Key words: asphalt, finite element, low-temperature cracking, reclaimed, recycled, thermal stresses.

Effect of coating thickness on thermal stresses in tungsten-coated optical fibers

2000 ◽  
Vol 87 (8) ◽  
pp. 3759-3762 ◽  
Author(s):  
Sham-Tsong Shiue ◽  
Pin-Tzu Lien ◽  
J.-L. He
Keyword(s):  
Optical Fibers ◽  
Coating Thickness ◽  
Thermal Stresses

Analysis on Thermal Stresses Adaptability to High Grade Asphalt Pavement Structure in Qinghai-Tibet Plateau

2015 ◽  
Vol 723 ◽  
pp. 395-399
Author(s):  
Ning Li ◽  
Xue Yan Zhou ◽  
Yu Xiang Tian ◽  
Peng Wei Liu
Keyword(s):  
Low Temperature ◽  
Thermal Stresses ◽  
Asphalt Pavement ◽  
Structure Type ◽  
Climatic Conditions ◽  
Tibet Plateau ◽  
Large Temperature ◽  
Climate Conditions ◽  
Pavement Structure ◽  
Qinghai Tibet Plateau

Permafrostregions have harsh climate conditions, continuous low temperature, abrupt cooling, large temperature difference, winds, etc. It has an extremely obvious influencetoasphalt pavement structures and materials. Take Lhasa-Gongga airport highway as an example to analyze the low temperature cracking problem of asphalt pavement caused by the climatic conditions. Using finite element method to contrast and analyze the thermal stresses variation of different asphalt layer, and recommend suitable asphalt pavement structure for Qinghai-Tibet plateau permafrost regions.The results indicate that the thermal stresses of asphalt layer gradually reduce along with the thickness direction of structure, moment of maximum and minimum value also been delayed and thermal stresses of base cause is fairly few. It can reduce thermal stresses of base cause and asphalt layer effectively while using the AC-25, and 4cmAC13 + 6cmAC20 + 8cmAC25 is recommended for Lhasa-Gonggaairport highway pavement structure type.

scholarly journals Solutions for thermally mismatched brazing operations for ceramic tokamak magnetic sensor

2016 ◽  
Vol 2016 (CICMT) ◽  
pp. 000058-000063 ◽  
Author(s):  
Caroline Jacq ◽  
Thomas Maeder ◽  
Benoit R. Ellenrieder ◽  
Philipp Windischhofer ◽  
Xinyue Jiang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thermal Stability ◽  
Low Temperature ◽  
High Frequency ◽  
Thermal Stresses ◽  
Magnetic Sensor ◽  
Temperature Gradients ◽  
Ceramic Technology ◽  
Vacuum Vessel ◽  
Main Substrate

Abstract To monitor high-frequency fluctuations of the equilibrium magnetic field in tokamaks, a 3D magnetic sensor has been developed. The sensor, which is positioned inside the vacuum vessel behind the protective tiles of the tokamak and is exposed to potential temperatures up to 400°C, is based on thick-film and LTCC (low-temperature co-fired ceramic) technology. To connect the sensor to the cabling that runs inside the vacuum vessel, mineral-insulated cables have to be brazed to the sensor to ensure electrical connection together with mechanical robustness and sufficient thermal stability. As the brazing temperature is about 600°C, direct brazing to the alumina sensor substrate can cause failure by cracking induced by thermal stresses. It arises both by temperature gradients stemming from the localised heating and by the high thermal mismatch of alumina with the braze and wire materials. In previous work, high stresses from temperature gradients were efficiently decoupled by brazing indirectly to alumina beams attached to the main substrate, and local thermal stresses between alumina and braze/wire by using a porous metallisation. However, as the slender alumina beams protruding out of the substrate are somewhat cumbersome and fragile, three alternatives were studied in the present work: 1) testing shorter and more robust beams, 2) replacing the alumina beam by a silver wire, and 3) depositing a porous temperature- and stress-decoupling dielectric to enable direct brazing on the main alumina substrate. These solutions are characterised with respect to their mechanical robustness and of the degree of thermal decoupling with the substrate they provide.

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