Stress Relaxation of Steel Tendons Used in Prestressed Concrete Under Conditions of Changing Applied Stress

2009 ◽  
pp. 42-42-17
Author(s):  
RJ Glodowski ◽  
GE Hoff
Keyword(s):  
Stress Relaxation ◽  
Applied Stress ◽  
Prestressed Concrete

Thermally Activated Dislocation Motion in an AS21 Alloy and Alloy Reinforced with Short Ceramic Fibres Studied at Elevated Temperatures

2013 ◽  
Vol 592-593 ◽  
pp. 71-74
Author(s):  
Zuzana Zdražilová ◽  
Zuzanka Trojanová ◽  
Kristián Máthis ◽  
Pavel Lukáč
Keyword(s):  
Magnesium Alloy ◽  
Stress Relaxation ◽  
Applied Stress ◽  
Elevated Temperatures ◽  
Activation Volume ◽  
Activation Enthalpy ◽  
Dislocation Motion ◽  
Thermally Activated ◽  
Effective Components ◽  
Thermally Activated Process

AS21 magnesium alloy (2.1Al-1Si-balance Mg in wt.%) and the alloy reinforced with short δ-Al2O3fibres (Saffil®) were deformed in compression at temperatures between 23 and 300 °C. Stress relaxation tests were performed in order to reveal features of the thermally activated dislocation motion. Internal and effective components of the applied stress have been estimated. The activation volume decreases with increasing effective stress. The values of the activation volume and the activation enthalpy indicate that the main thermally activated process in the alloy as well as in the composite is the dislocation motion in non-compact planes.

scholarly journals An Experimental Analysis of Stress Relaxation in Nonwoven Fabrics

2014 ◽  
Vol 18 (4) ◽  
pp. 38-43
Author(s):  
Sajid Ahmed Qureshi ◽  
Alhayat Getu Temesgen
Keyword(s):  
Stress Relaxation ◽  
Applied Stress ◽  
Strain Gauge ◽  
Experimental Analysis ◽  
Considerable Extent ◽  
Nonwoven Fabrics ◽  
Gauge Principle ◽  
Nonwoven Materials ◽  
External Loads ◽  
Constant Period

The current research deals with an analysis of stress relaxation in nonwoven fabrics with different gsm values with a view to understand how these nonwovens behave under an applied stress for a given load over a constant period of time. An electronic stress relaxation tester is indigenously designed for this purpose which works on the strain gauge principle of measuring loads applied to the specimen at any given instant of time during the experiment. The respective stress values are calculated for corresponding load values for each specimen with every thirty seconds passage of time. The results obtained are graphically analyzed and it is revealed that the stress relaxation percentage is significantly different for the same nonwoven materials, but with different gsm values. It is observed that nonwovens do possess the property of decaying the stress generated due to external loads and the extent to which this happens depends to a considerable extent on the gsm of the structure along with other factors, like type of fiber and bonding.

Solid Solution Strengthening Behavior of 25Cr-20Ni Austenite Stainless Steel

2004 ◽  
Vol 261-263 ◽  
pp. 1209-1214
Author(s):  
I.D. Park ◽  
Seok Hwan Ahn ◽  
Ki Woo Nam
Keyword(s):  
Solid Solution ◽  
Stress Relaxation ◽  
Plastic Strain ◽  
Applied Stress ◽  
Abrupt Change ◽  
Relaxation Curve ◽  
Stress Relaxation Test ◽  
Free Flight ◽  
Solid Solution Strengthening ◽  
Solution Strengthening

The purpose of this paper is to investigate the effect of solid solution strengthening on the high temperature creep strength of STS310J1TB. To make clear the effect of solid solution strengthening, the stress abrupt change test was carried out to observe the instantaneous plastic strain and the stress relaxation test was carried out to investigate the ratio of solid solution strengthening to applied stress. The instantaneous plastic strain was observed in the stress abrupt change test of STS310S, while it was absent in STS310J1TB. This clearly indicates that the dislocations glide viscously in STS310J1TB, while they move in a free flight manner in STS310S. As a result of TEM observation, the dislocation structure of STS310J1TB is more uniform than that of STS310S. From the analysis of the stress relaxation curve, the effective stress to total applied stress was found to be about 16 %.

Plastic Deformation in Microtomed Sections

1971 ◽  
Vol 29 ◽  
pp. 458-459
Author(s):  
J. Temple Black
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Applied Stress ◽  
Elastic Strain ◽  
High Strain ◽  
Tool Material ◽  
Cutting Edge ◽  
Material Structure ◽  
Geometrical Constraints

The output of the ultramicrotomy process with its high strain levels is dependent upon the input, ie., the nature of the material being machined. Apart from the geometrical constraints offered by the rake and clearance faces of the tool, each material is free to deform in whatever manner necessary to satisfy its material structure and interatomic constraints. Noncrystalline materials appear to survive the process undamaged when observed in the TEM. As has been demonstrated however microtomed plastics do in fact suffer damage to the top and bottom surfaces of the section regardless of the sharpness of the cutting edge or the tool material. The energy required to seperate the section from the block is not easily propogated through the section because the material is amorphous in nature and has no preferred crystalline planes upon which defects can move large distances to relieve the applied stress. Thus, the cutting stresses are supported elastically in the internal or bulk and plastically in the surfaces. The elastic strain can be recovered while the plastic strain is not reversible and will remain in the section after cutting is complete.

Stress Relaxation and the Formation of Silicides in the Process of the Crystallization of NI-NB Films on SI

1991 ◽  
Vol 49 ◽  
pp. 898-899
Author(s):  
N. Rozhanski ◽  
V. Lifshitz
Keyword(s):  
Thin Films ◽  
Stress Relaxation ◽  
Integrated Circuits ◽  
Direct Evidence ◽  
Alloy Film ◽  
Diffusion Barriers ◽  
Effective Barrier

Thin films of amorphous Ni-Nb alloys are of interest since they can be used as diffusion barriers for integrated circuits on Si. A native SiO2 layer is an effective barrier for Ni diffusion but it deformation during the crystallization of the alloy film lead to the appearence of diffusion fluxes through it and the following formation of silicides. This study concerns the direct evidence of the action of stresses in the process of the crystallization of Ni-Nb films on Si and the structure of forming NiSi2 islands.

The effects of strain and strain rate on residual microstructures in copper

1986 ◽  
Vol 44 ◽  
pp. 420-421
Author(s):  
M. F. Stevens ◽  
P. S. Follansbee
Keyword(s):  
Strain Rate ◽  
Applied Stress ◽  
Threshold Stress ◽  
Rate Sensitivity ◽  
Viscous Drag ◽  
Strain Rates ◽  
Strain And Strain Rate ◽  
Threshold Strength ◽  
Mechanism Transition ◽  
Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

A Transmission Electron Microscopical Investigation of Phase Transformations in TiNi

1980 ◽  
Vol 38 ◽  
pp. 340-341
Author(s):  
P. Moine ◽  
G. M. Michal ◽  
R. Sinclair
Keyword(s):  
Electron Microscopy ◽  
Phase Transformations ◽  
Applied Stress ◽  
Structural Changes ◽  
Microscopical Investigation ◽  
Temperature Range ◽  
Transmission Electron ◽  
Electron Microscopical ◽  
Diffraction Effects ◽  
Microscopy Images

Premartensitic effects in near equiatomic TiNi have been pointed out by several authors(1-5). These include anomalous contrast in electron microscopy images (mottling, striations, etc. ),diffraction effects(diffuse streaks, extra reflections, etc.), a resistivity peak above Ms (temperature at which a perceptible amount of martensite is formed without applied stress). However the structural changes occuring in this temperature range are not well understood. The purpose of this study is to clarify these phenomena.

BDNF Val⁶⁶Met polymorphism to generalized anxiety disorder pathways: Indirect effects via attenuated parasympathetic stress-relaxation reactivity.

2020 ◽  
Vol 129 (3) ◽  
pp. 237-247 ◽  
Author(s):  
Hsin-An Chang ◽  
Wen-Hui Fang ◽  
Yia-Ping Liu ◽  
Nian-Sheng Tzeng ◽  
Jia-Fwu Shyu ◽  
...  
Keyword(s):  
Anxiety Disorder ◽  
Stress Relaxation ◽  
Generalized Anxiety Disorder ◽  
Indirect Effects ◽  
Generalized Anxiety
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