Influence of stress relaxation in primary coatings on low-temperature attenuation in optical fibers

1994 ◽  
Author(s):  
Srinath S. Reddy ◽  
Bob J. Overton ◽  
Stephanie M. Watson
Keyword(s):  
Stress Relaxation ◽  
Low Temperature ◽  
Optical Fibers

Rate Dependent Constitutive Equations of Cyclic Softening

1985 ◽  
Vol 40 (7) ◽  
pp. 653-665
Author(s):  
J. S. Mshana ◽  
A. S. Krausz
Keyword(s):  
Stress Relaxation ◽  
Low Temperature ◽  
Constitutive Equations ◽  
Strain Softening ◽  
Structural Characteristics ◽  
High Stress ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Cyclic Softening ◽  
Stress Softening

Constitutive equations of cyclic strain and stress softening for materials with low internal stress levels are derived from the rate theory. The study shows that over the high stress and low temperature range where the description of plastic flow in cyclic softening can be approximated with activation over a single energy barrier, cyclic strain softening is well related to stress relaxation process while cyclic stress softening is related to creep process. The material structural characteristics for cyclic strain softening, cyclic stress softening and stress relaxation are identical. Subsequently, it is shown that cyclic stress and strain softening within the high stress and low temperature range can be evaluated from the constitutive equations using the material structural characteristics measured from a simple stress relaxation test.

Grain growth behavior of a nanostructured 5083 Al–Mg alloy

2001 ◽  
Vol 16 (4) ◽  
pp. 938-944 ◽  
Author(s):  
V. L. Tellkamp ◽  
S. Dallek ◽  
D. Cheng ◽  
E. J. Lavernia
Keyword(s):  
Activation Energy ◽  
Stress Relaxation ◽  
Low Temperature ◽  
Grain Boundaries ◽  
Relaxation Process ◽  
Grain Growth ◽  
Alloy Powder ◽  
Growth Behavior ◽  
Mg Alloy ◽  
Grain Growth Behavior

A nanostructured 5083 Al–Mg alloy powder was subjected to various thermal heat treatments in an attempt to understand the fundamental mechanisms of recovery, recrystallization and grain growth as they apply to nanostructured materials. A low-temperature stress relaxation process associated with reordering of the grain boundaries was found to occur at 158 °C. A bimodal restructuring of the grains occurred at 307 °C for the unconstrained grains and 381 °C for the constrained grains. An approximate activation energy of 5.6 kJ/mol was found for the metastable nanostructured grains, while an approximate activation energy of 142 kJ/mol was found above the restructuring temperature.

Three-dimensional fluidic microsystem fabricated in Low Temperature Cofired Ceramic Technology

2006 ◽  
Vol 3 (3) ◽  
pp. 145-151 ◽  
Author(s):  
Leszek J. Golonka ◽  
Tomasz Zawada ◽  
Henryk Roguszczak ◽  
Karol Malecha ◽  
Michal Chudy ◽  
...  
Keyword(s):  
Low Temperature ◽  
Optical Fibers ◽  
Temperature Sensor ◽  
Light Transmission ◽  
Three Dimensional ◽  
Microfluidic System ◽  
Ceramic Technology ◽  
Fluorescence Measurements ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

A three-dimensional (3D) Low Temperature Cofired Ceramics (LTCC) fluidic microsystem integrated with an optical detection unit is presented in this article. The structure is applied to quantitative analysis of chemical compounds using colorimetric methods. The fabricated microfluidic system consists of a serpentine mixer, fluidic channels, heater, embedded temperature sensor and integrated optical fibers for detection of light transmission and/or fluorescence. A new inexpensive material for the embedded temperature sensor is described. The fluidic system is designed using computer CFD (Computational Fluid Dynamics) simulations. Fluid flow in the mixer is observed through a transparent polymer material bonded to the LTCC structure. The importance of positioning of optical fibers and their influence on the absorbance and fluorescence measurements is presented.

Low temperature stress relaxation of nanocrystalline nickel

1995 ◽  
Vol 30 (11) ◽  
pp. 2956-2961 ◽  
Author(s):  
L. I. Trusov ◽  
T. P. Khvostantseva ◽  
V. A. Solov'ev ◽  
V. A. Mel'nikova
Keyword(s):  
Stress Relaxation ◽  
Low Temperature ◽  
Temperature Stress ◽  
Low Temperature Stress ◽  
Nanocrystalline Nickel

The Effect of Ultra-Low Temperature Treatments on the Stress in Aluminum Metallization on Silicon Wafers

1994 ◽  
Vol 338 ◽  
Author(s):  
Frank Baldwin ◽  
Paul H. Holloway ◽  
Mark Bordelon ◽  
Thomas R. Watkins
Keyword(s):  
Stress Relaxation ◽  
Low Temperature ◽  
Thermal Cycling ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Silicon Wafers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aluminum Metallization ◽  
Low Temperature Treatments

ABSTRACTThe stresses in Al-0.75w%Si-0.5w%Cu unpatterned metallization on silicon wafers have been measured using substrate curvature and x-ray diffraction techniques after quenching in liquid nitrogen. Stresses were measured with and without phospho-silicate glass overlayers and SiO2 underlayers, and thermal cycling followed by relaxation at room temperature. It was found that cooling the substrates to 77 K and warming to room temperature caused the metallization stress to go from tensile to compressive. Subsequent heating of the substrates to above ∼70°C followed by cooling to room temperature caused the stress to become tensile. Both compressive and tensile stresses were found to relax at room temperature with a time constant of 2.3 ± 0.2 hours. The magnitude of stress relaxation was a function of temperature, being about 20 MPa after heating to 240°C. The metallization exhibited both compressive and tensile flow stresses of ∼100 MPa near room temperature.

LOW TEMPERATURE CREEP AND STRESS RELAXATION FOR PEIERLS BARRIER IN CUBIC METALS

1995 ◽  
Vol 09 (05) ◽  
pp. 285-289 ◽  
Author(s):  
S. A. MAJEED ◽  
N. FAROOQUI ◽  
M. A. AHMED ◽  
S. M. RAZA
Keyword(s):  
Stress Relaxation ◽  
Low Temperature ◽  
Activation Volume ◽  
Face Centered Cubic ◽  
Cubic Metals ◽  
Temperature Creep ◽  
Peierls Barrier ◽  
Face Centered ◽  
Low Temperature Creep ◽  
Creep And Stress Relaxation

The relation for low temperature creep and stress relaxation is developed for Peierls barrier in cubic metals using single barrier stochastic model, with special reference to face-centered cubic crystals. Our conjecture that the strain enhancement is responsible for an increase in activation volume is verified through nondimensionality, i.e. by shear traction number.

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