scholarly journals Determination of Residual Stresses in WCu Gradient Materials

1999 ◽  
Vol 33 (1-4) ◽  
pp. 207-217 ◽  
Author(s):  
G. Bokuchava ◽  
N. Shamsutdinov ◽  
J. Schreiber ◽  
M. Stalder
Keyword(s):  
Residual Stress ◽  
High Resolution ◽  
Elastic Behaviour ◽  
Gradient Materials ◽  
Linear Elastic ◽  
Step Functions ◽  
Order Of Magnitude ◽  
Copper Phase ◽  
Experimental Values

Residual stress measurements were carried out on copper–tungsten gradient materials by means of neutron diffraction on the High Resolution Fourier Diffractometer on IBR-2, JINR, Dubna. The samples so far investigated had a concentration profile that approximates the gradient by step functions. The results show an averaged positive stress (stretch) in the copper phase and negative (compression) in the tungsten phase. A comparison to analytical linear elastic calculations shows that the measured values are nearly an order of magnitude too low, whereas however, a qualitative agreement of the stress distribution exists. That this quantitative discrepancy can be attributed to the model's simplifying assumption of pure elastic behaviour can be shown by recent calculations that also include plasticity and show a much better agreement with the experimental values. Single peak evaluation also strongly suggests that plasticity does indeed play a significant role.

A Critical Examination of Sachs’ Material-Removal Method for Determination of Residual Stress

2003 ◽  
Author(s):  
Anthony P. Parker
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Critical Examination ◽  
Fatigue Lifetime ◽  
Experimental Procedure ◽  
Linear Elastic ◽  
Order Of Magnitude ◽  
Hoop Stresses ◽  
Elastic Unloading

Sachs’ method is an experimental procedure used primarily in the determination of residual stresses in autofrettaged thick cylinders. In its usual form it involves fixing axial and hoop direction strain gauges to the OD of a tube; strain readings are then obtained after each incremental removal of material from the bore. Sachs’ analysis assumes that the remaining tube unloads in linear-elastic fashion throughout the process and that superposition may therefore be employed to quantify the residual stresses within the original tube. By numerical simulation of two complete Sachs’ experimental sequences with ‘open end’ conditions it is demonstrated that the assumption of elastic unloading is invalidated by the Bauschinger effect. Sachs’ method thereby overestimates compressive residual bore hoop stresses in a typical tube by between 24% and 43%. If used as the basis for cyclic pressurization fatigue lifetime predictions with pre-existing cracks, such discrepancies will cause overestimates in fatigue lifetime of an order of magnitude. Sachs’ experimental procedure is therefore not recommended as a reliable or conservative method for determination of residual stress.

A Critical Examination of Sachs’ Material-Removal Method for Determination of Residual Stress

2004 ◽  
Vol 126 (2) ◽  
pp. 234-236 ◽  
Author(s):  
Anthony P. Parker
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Critical Examination ◽  
Fatigue Lifetime ◽  
Experimental Procedure ◽  
Linear Elastic ◽  
Order Of Magnitude ◽  
Hoop Stresses ◽  
Elastic Unloading

Sachs’ method is an experimental procedure used primarily in the determination of residual stresses in autofrettaged thick cylinders. In its usual form it involves fixing axial and hoop direction strain gauges to the OD of a tube; strain readings are then obtained after each incremental removal of material from the bore. Sachs’ analysis assumes that the remaining tube unloads in linear-elastic fashion throughout the process and that superposition may therefore be employed to quantify the residual stresses within the original tube. By numerical simulation of two complete Sachs’ experimental sequences with “open end” conditions it is demonstrated that the assumption of elastic unloading is invalidated by the Bauschinger effect. Sachs’ method thereby overestimates compressive residual bore hoop stresses in a typical tube by between 24% and 43%. If used as the basis for cyclic pressurization fatigue lifetime predictions with pre-existing cracks, such discrepancies will cause overestimates in fatigue lifetime of an order of magnitude. Sachs’ experimental procedure is therefore not recommended as a reliable or conservative method for determination of residual stress.

Stress of Homogeneous and Graded Epitaxial Thin Films Studied by Full-Shape Analysis of High Resolution Reciprocal Space Maps

2013 ◽  
Vol 768-769 ◽  
pp. 249-256
Author(s):  
Tatjana Ulyanenkova ◽  
Andrei Benediktovitch ◽  
Maksym Myronov ◽  
John Halpin ◽  
Stephen Rhead ◽  
...  
Keyword(s):  
Solid Solution ◽  
Residual Stress ◽  
High Resolution ◽  
Bragg Peak ◽  
Solution Concentration ◽  
Peak Position ◽  
Reciprocal Space ◽  
Epitaxial Thin Films ◽  
Peak Shape

The Bragg peak position of a homogeneous solid solution epitaxial film is directly related to the solid solution concentration, film strain and, consequently, residual stress. The peak shape contains information about defects present in the sample. In the case of compositionally graded epitaxial films the situation is more complex since instead of a single Bragg peak there is a continuous diffracted intensity distribution which can be measured by means of recording high resolution reciprocal space maps. We analyse the thin film residual stress based not only on peak positions, but taking into account the defect-induced peak shape as well. Consideration of the peak shape enables the determination of the stress depth profile in the case of graded films and to imporves the accuracy in the case of homogeneous films.

scholarly journals Determination of 234U and 238U Activities in Soil by Liquid Scintillation and High-Resolution Alpha Spectrometry

2021 ◽  
Vol 8 (2) ◽  
pp. 115-120
Author(s):  
Montero-Cabrera María Elena ◽  
Caraveo-Castro Carmen del Rocío ◽  
Méndez-García Carmen Grisel ◽  
Mendieta-Mendoza Aurora ◽  
Rentería-Villalobos Marusia ◽  
...  
Keyword(s):  
High Resolution ◽  
Alpha Spectrometry ◽  
Liquid Scintillation ◽  
Activity Concentration ◽  
Ion Exchange Resin ◽  
Chemical Recovery ◽  
Electrode Position ◽  
Arid Environments ◽  
Order Of Magnitude

Uranium is a radioactive element with a special presence in the rocks, waters, sediments, soils, and plants at the state of Chihuahua. The activity ratio of 238U/234U is used to explain the uranium transport by surface water and its deposition in arid environments. In this work, the activity concentration of natural U isotopes is determined by PERALS liquid scintillation and high-resolution alpha spectrometry (AS, Canberra camera 7401VR) in the Environmental Radiological Surveillance Laboratory (LVRA) at CIMAV, Chihuahua. Uranium is extracted from soils through the scintillating liquid extractor URAEX for PERALS, with chemical recovery (CR) of 80 - 85 %, and through the ion exchange resin UTEVA + electrode position by the Hallstadius method, with CR of 85 - 90 %, for AS. The procedures of 234U and 238U activity concentration (AC) determination in soils were validated by their application to the certified reference material IAEA-375. The resulting values were in the reference range of the certified or informative values. Both procedures were applied to 6 representative soil samples, with AC of the same order of magnitude or greater, and similar CR and compatible results. Both procedures are satisfactory for the purposes of LVRA research and in general.

scholarly journals Analysing the Critical Orientation of Seismic Loading in 3D Buildings: Preliminary Results for Constant Lateral Forces

2018 ◽  
Vol 2 (3) ◽  
pp. 2-15 ◽  
Author(s):  
Despoina Skoulidou ◽  
Xavier Romão
Keyword(s):  
Critical Angle ◽  
Structural Characteristics ◽  
Seismic Loading ◽  
Seismic Excitation ◽  
Elastic Behaviour ◽  
Angle Of Incidence ◽  
Linear Elastic ◽  
Lateral Forces ◽  
Linear Elastic Behaviour

The angle of seismic excitation has been proven to be an important factor when analysing the 3D behaviour of buildings. However, modern earthquake-related standards only cover partially the effects of this factor and practicable results of relevant studies are still limited. The proposed paper focuses on the determination of the critical angle of incidence based on the building's structural characteristics. An analytical expression is developed to define the critical angle for the case of single storey buildings and a special category of multi storey buildings under constant lateral forces assuming linear elastic behaviour of the structures.

scholarly journals High resolution determination of local residual stress gradients in single- and multilayer thin film systems

2016 ◽  
Vol 103 ◽  
pp. 616-623 ◽  
Author(s):  
R. Treml ◽  
D. Kozic ◽  
J. Zechner ◽  
X. Maeder ◽  
B. Sartory ◽  
...  
Keyword(s):  
Thin Film ◽  
Residual Stress ◽  
High Resolution ◽  
Multilayer Thin Film ◽  
Stress Gradients

Boron trifluoride: The analysis of 2v3 and the determination of ζ33

1968 ◽  
Vol 46 (8) ◽  
pp. 977-985 ◽  
Author(s):  
Chris W. Brown ◽  
John Overend
Keyword(s):  
High Resolution ◽  
Bond Length ◽  
Boron Trifluoride ◽  
Force Constants ◽  
Experimental Values

The 2v3 bands of 10BF3 and 11BF3 have been studied at high resolution. The experimental values of the Coriolis coefficient ζ33 are 0.7808 ± 0.0036 for 10BF3 and 0.7438 ± 0.0047 for 11BF3. The BF bond length is found to be 1.3102 ± 0.0012 Å. The Coriolis coefficients have been used to fix the E′ species symmetry force constants.

High-resolution microscopy of twin boundaries in gold

1987 ◽  
Vol 45 ◽  
pp. 260-261
Author(s):  
William Krakow ◽  
David A. Smith
Keyword(s):  
High Resolution ◽  
Specimen Preparation ◽  
Gold Films ◽  
Boundary Area ◽  
Transmission Electron ◽  
Recent Developments ◽  
Tilt Boundaries ◽  
High Resolution Microscopy ◽  
Twist Boundaries

Recent developments in specimen preparation, imaging and image analysis together permit the experimental determination of the atomic structure of certain, simple grain boundaries in metals such as gold. Single crystal, ∼125Å thick, (110) oriented gold films are vapor deposited onto ∼3000Å of epitaxial silver on (110) oriented cut and polished rock salt substrates. Bicrystal gold films are then made by first removing the silver coated substrate and placing in contact two suitably misoriented pieces of the gold film on a gold grid. Controlled heating in a hot stage first produces twist boundaries which then migrate, so reducing the grain boundary area, to give mixed boundaries and finally tilt boundaries perpendicular to the foil. These specimens are well suited to investigation by high resolution transmission electron microscopy.

High-Resolution Image Simulation of a Tilted Crystal

1990 ◽  
Vol 48 (1) ◽  
pp. 68-69
Author(s):  
C. J. D. Hetherington
Keyword(s):  
High Resolution ◽  
Crystal Thickness ◽  
Thin Specimen ◽  
Atomic Structures ◽  
Kikuchi Lines ◽  
High Resolution Images ◽  
Final Estimate ◽  
Simulated Images ◽  
Habit Planes

Most high resolution images are not directly interpretable but must be compared with simulations based on model atomic structures and appropriate imaging conditions. Typically, the only parameters that are adjusted, in addition to the structure models, are crystal thickness and microscope defocus. Small tilts of the crystal away from the exact zone axis have only rarely been considered. It is shown here that, in the analysis of an image of a silicon twin intersection, the crystal tilt could be accurately estimated and satisfactorily included in the simulations.The micrograph shown in figure 1 was taken as part of an HREM study of indentation-induced hexagonal silicon. In this instance, the intersection of two twins on different habit planes has driven the silicon into hexagonal stacking. However, in order to confirm this observation, and in order to investigate other defects in the region, it has been necessary to simulate the image taking into account the very apparent crystal tilt. The inability to orientate the specimen at the exact [110] zone was influenced by i) the buckling of the specimen caused by strains at twin intersections, ii) the absence of Kikuchi lines or a clearly visible Laue circle in the diffraction pattern of the thin specimen and iii) the avoidance of radiation damage (which had marked effects on images taken a few minutes later following attempts to realign the crystal.) The direction of the crystal tilt was estimated by observing which of the {111} planes remained close to edge-on to the beam and hence strongly imaged. Further refinement of the direction and magnitude of the tilt was done by comparing simulated images to experimental images in a through-focal series. The presence of three different orientations of the silicon lattice aided the unambiguous determination of the tilt. The final estimate of a 0.8° tilt in the 200Å thick specimen gives atomic columns a projected width of about 3Å.

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