scholarly journals Relaxation of stresses in annealing glass

1945 ◽  
Vol 34 (2) ◽  
pp. 199 ◽  
Author(s):  
A.Q. Tool
Keyword(s):  
Relaxation Of Stresses ◽  
Annealing Glass

Stress development and relaxation in copper films during thermal cycling

1993 ◽  
Vol 8 (8) ◽  
pp. 1845-1852 ◽  
Author(s):  
M.D. Thouless ◽  
J. Gupta ◽  
J.M.E. Harper
Keyword(s):  
Thermal Cycling ◽  
Integrated Circuit ◽  
Temperature Hysteresis ◽  
Copper Films ◽  
Cu Films ◽  
Dislocation Glide ◽  
Temperature Range ◽  
Cu Film ◽  
Relaxation Of Stresses ◽  
Power Law Creep

The reliability of integrated-circuit wiring depends strongly on the development and relaxation of stresses that promote void and hillock formation. In this paper an analysis based on existing models of creep is presented that predicts the stresses developed in thin blanket films of copper on Si wafers subjected to thermal cycling. The results are portrayed on deformation-mechanism maps that identify the dominant mechanisms expected to operate during thermal cycling. These predictions are compared with temperature-ramped and isothermal stress measurements for a 1 μm-thick sputtered Cu film in the temperature range 25–450 °C. The models successfully predict both the rate of stress relaxation when the film is held at a constant temperature and the stress-temperature hysteresis generated during thermal cycling. For 1 μm-thick Cu films cycled in the temperature range 25–450 °C, the deformation maps indicate that grain-boundary diffusion controls the stress relief at higher temperatures (>300 °C) when only a low stress can be sustained in the films, power-law creep is important at intermediate temperatures and determines the maximum compressive stress, and that if yield by dislocation glide (low-temperature plasticity) occurs, it will do so only at the lowest temperatures (<100 °C). This last mechanism did not appear to be operating in the film studied for this project.

scholarly journals Evaluation of the rheological properties of photopolymers used in Polymer Jetting technology

2019 ◽  
Vol 254 ◽  
pp. 07001
Author(s):  
Czesław Kundera ◽  
Tomasz Kozior
Keyword(s):  
Rheological Properties ◽  
Technological Parameter ◽  
Liquid Polymer ◽  
Compressive Stresses ◽  
Relaxation Of Stresses ◽  
Photo Curing

The paper presents the results of tests related to relaxation of stresses in models of samples made using the technology of photo-curing of liquid polymer resins polyjet modeling (PJM). The models of the samples were made using two types of materials: VeroWhite and FullCure 720. The tests were performed on samples in compliance with the PN-EN ISO 3384 standard. The technological parameter whose impact was analyzed was the orientation of the models on the virtual building platform, which was defined with three variability levels (0°, 45°, and 90°). The tests demonstrated that the position of the models on the building platform has a significant impact on the relaxation of compressive stresses. Moreover, the most advantageous positions of the models on the building platform from the standpoint of relaxation of stresses were determined.

scholarly journals INFLUENCE OF INCREASED TEMPERATURE ON THE DYNAMIC PROPERTIES OF ASPEN

2021 ◽  
Vol 83 (1) ◽  
pp. 5-21
Author(s):  
A.M. Bragov ◽  
A.Yu. Konstantinov ◽  
A.K. Lomunov ◽  
T.N. Yuzhina
Keyword(s):  
Experimental Data ◽  
Elevated Temperatures ◽  
Dynamic Properties ◽  
Stress Strain ◽  
Horizontal Section ◽  
Mean Values ◽  
Damping Material ◽  
Deformation Properties ◽  
Relaxation Of Stresses ◽  
Strength And Deformation

As a damping material in the structures of containers for the transportation of hazardous materials, along with plastic metals, fiber-claydite concrete and synthetic foams, it is proposed to use wood of different species. Since containers are transported in different climate regimes, there is an urgent need to study the properties of wood at elevated temperatures. The paper presents the results of dynamic tests of aspen under uniaxial compression under conditions of temperature increased to +60°C. The tests were carried out according to the Kolsky method on a Hopkinson split-bar setup. To study the anisotropy of properties, aspen samples were made and tested by cutting samples along and across the direction of the grains. As a result of processing the experimental data, dynamic stress-strain curves were obtained. According to the experimental data, there are determined the stresses at which the integrity of the samples were violated. The mean values of the moduli of deformation in the active loading regions of stress-strain curves are also presented. The highest slope of the load sections and the highest breaking stresses were observed for the specimens when loaded along the grains, and the smallest values of these parameters were noted when loaded across the grains. For specimens loaded along grains at strain rates above 1500 s–1, after reaching the limiting stress values, a decrease (relaxation) of stresses is observed with increasing deformations. For specimens loaded across the grains, an almost horizontal section the diagrams of deforming or even with some strengthening is more typical. The effect of elevated temperature on the strength and deformation properties of aspen is estimated. There is a tendency towards some decrease in the diagrams at a temperature of +60 °C in comparison with the diagrams at room temperature. In this case, both the moduli in the loading and unloading sections and the limiting (breaking) stresses decrease. The obtained features of the behavior of aspen specimens at elevated temperatures should be taken into account when modeling deforming wood.

RHEOLOGICAL MODELING OF THE STRESS-STRAIN IN FLAT COMPACTION OF COMPOSITE MATERIALS

2020 ◽  
pp. 78-86
Author(s):  
Б. М. Кумицкий ◽  
Н. А. Саврасова ◽  
А. В. Николайчик ◽  
Е. С. Аралов
Keyword(s):  
Continuous Medium ◽  
Uniaxial Stress ◽  
Two Dimensions ◽  
Inertial Effects ◽  
Stress Strain ◽  
Pressing Process ◽  
Relaxation Of Stresses ◽  
Deformed State ◽  
Rheological Modeling ◽  
Coefficient Of Viscosity

Постановка задачи. В статье исследуется деформационное поведение композиционного материала в процессе его плоского прессования. Для решения этой проблемы предложена реологическая модель, в основе которой лежат явления, протекающие в вязкой (ньютоновской) несжимаемой жидкости, занимающей объем между двумя сближающимися с малой скоростью абсолютно жесткими параллельными плоскостями конечных размеров прямоугольной формы. В рамках механики сплошной среды в условиях плоского деформированного состояния решается задача в двух измерениях о медленном течении в отсутствии объемных сил и инерционных эффектов. При этом решение уравнения движения с условиями неразрывности сводится к известному уравнению Лапласа. Кроме того, на основе модели линейной вязкоупругости и одноосного напряженного состояния предпринята попытка описания релаксационных явлений, протекающих в затвердевающем композите по окончании процесса активного прессования. Результаты и выводы. Получены аналитические зависимости силовых параметров напряженно-деформированного состояния прессуемого композита; получены соотношения для кинематических характеристик процесса прессования; получено выражение для релаксации напряжений в процессе технологической выдержки материала под давлением после окончания активного прессования. Результаты исследования позволяют экспериментально определять численные значения динамического коэффициента вязкости и времени релаксации напряжения, которые являются важными характеристиками при управлении процессами прессования. Statement of the problem. The article investigates the deformation behavior of a composite material in the process of its flat pressing. To solve this problem, a rheological model is proposed which is based on the phenomena occurring in a viscous (Newtonian) incompressible fluid that occupies the volume between two absolutely rigid parallel planes of finite dimensions of rectangular shape approaching at a low speed. Within the framework of mechanics of a continuous medium under conditions of a plane deformed state, the problem is addressed in two dimensions about a slow flow in the absence of volume forces and inertial effects. In this case, the solution of the equation of motion with continuity conditions is reduced to the well-known Laplace equation. In addition, based on the model of linear viscoelasticity and uniaxial stress, an attempt has been made to describe the relaxation phenomena occurring in the solidifying composite at the end of the active pressing process. Results and conclusions. Analytical dependences of the power parameters of the stress-strain of the compressed composite are obtained; relations for the kinematic characteristics of the pressing process are identified; an expression is designed for the relaxation of stresses during the technological holding of the material under pressure following the end of active pressing. The results of the study make it possible to experimentally determine the numerical values of the dynamic coefficient of viscosity and stress relaxation time which are important characteristics in controlling the pressing processes.

Annealing Glass

1916 ◽  
Vol 17 (2) ◽  
pp. 72-73
Author(s):  
C V Boys
Keyword(s):  
Annealing Glass

The design of equipment and thermal routines for annealing glass particles

1984 ◽  
Vol 26 (2) ◽  
pp. 139-146 ◽  
Author(s):  
J. Locke ◽  
C.A. Hayes ◽  
D.G. Sanger
Keyword(s):  
Annealing Glass

Model of Subgrain Structure Formation in HTS Cuprates and Ferropnictides

2012 ◽  
Vol 1434 ◽  
Author(s):  
Constantin G. Tretiatchenko ◽  
Vassily L. Svetchnikov ◽  
Harold Wiesmann
Keyword(s):  
Film Growth ◽  
Lattice Mismatch ◽  
Subgrain Size ◽  
Finite Size ◽  
Interface Energy ◽  
Rotational Relaxation ◽  
Subgrain Structure ◽  
Relaxation Of Stresses ◽  
Validity Range ◽  
Edge Dislocations

ABSTRACTWe have modified the model of rotational relaxation of stresses at mismatched interface by taking into account elastic strains of the growing film. This extended the model validity range to a wider class of compounds including pnictides. The model describes formation of low angle boundaries consisting of threading edge dislocations. Calculated interface energy shows that rotational relaxation occurs due to finite size of clusters and to non-equilibrium effect of the film growth. Subgrain size and expected angle of domain rotation depending on the lattice mismatch have been estimated. Unusual effect of increasing angle between the film subgrains at reduction of the deposition rate is predicted. The computed parameters of subgrains are consistent with the observed film nanostructure.

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