scholarly journals Procedures for Residual Stress Analysis in Textured and in Coarse Grained Materials

1995 ◽  
Vol 23 (3) ◽  
pp. 173-183 ◽  
Author(s):  
W. Reimers ◽  
R. Dupke
Keyword(s):  
Residual Stress ◽  
Elastic Constants ◽  
Elastic Anisotropy ◽  
Orientation Distribution ◽  
Coarse Grained ◽  
Fine Grained ◽  
Experimental Strain ◽  
Anisotropic Elastic ◽  
The Individual ◽  
Experimental Findings

For the investigation of residual stresses by means of X-ray diffraction, special procedures for the registration and evaluation of the experimental strain data are necessary for textured and coarse grained materials. In both cases inhomogeneous diffraction intensity patterns are present which lead to the formation of intensity poles or even to Bragg reflections. Such experimental findings indicate also that the material properties within the investigated gauge volume are anisotropic so that the evaluation of the experimental strain up to stress values requires the introduction of anisotropic elastic constants. For the residual stress investigation of textured and fine grained materials averaging procedures using short wavelength radiation are discussed. A more detailed insight also in the microstress states may be obtained from the measurement of several different reflections whereby the effects of the elastic anisotropy may be corrected for by including the orientation distribution function as calculated from different poles figures. For coarse grained materials it is experimentally possible to determine the strain state of the individual crystallites so that their anisotropy is directly included in the evaluation of the stress data by using the single crystal elastic constants. The macroscopic residual stress values may then be obtained from the averaging over stress values of several crystallites.

Direct X-Ray Measurement of Residual Strains in Textured Steel

1983 ◽  
Vol 27 ◽  
pp. 197-206
Author(s):  
C. P. Gazzara
Keyword(s):  
Residual Stress ◽  
Crystal Lattice ◽  
Elastic Constants ◽  
Random Distribution ◽  
Elastic Anisotropy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Residual Strains ◽  
Residual Stress Analysis ◽  
Textured Materials

One of the most detrimental effects on the accuracy of an X-ray diffraction residual stress analysis, XRDRSA(l), is found in the examination of textured materials. The degree of elastic anisotropy and texture is in general agreement with the extent of the error in the residual stress. Several approaches have been made to correct for the effects of texture, particularly involving experimental techniques. Reviews of such efforts are given by H. D811e(2), v.M. Hauk﹛3) and G. Maeder, J.L. Lebrun and J.M. Sprauel (4), just to mention a few.A brief chronology of the texture corrections involved in XRDRSA follows. With isotropic materials the d spacing of a crystal lattice, d, is assumed to vary linearly with sin2ψ. With textured materials the d vs sin2ψ relationship is nonlinear. This is due to the anisotropy of the elastic constants and their departure from a random distribution, or taking on a preferred orientation.

scholarly journals Ultrasonic Pulse Velocities And Dynamic Elastic Constants Of Sandstones From The Semanggol Formation, Beris Dam, Kedah Darul Aman

Warta Geologi ◽  
2021 ◽  
Vol 47 (1) ◽  
pp. 1-8
Author(s):  
John K. Raj
Keyword(s):  
Grain Size ◽  
Elastic Constants ◽  
Ultrasonic Pulse ◽  
Coarse Grained ◽  
Unconfined Compression ◽  
Ultrasonic Velocities ◽  
Unconfined Compression Test ◽  
Fine Grained ◽  
Wave Velocities ◽  
Shear Wave Velocities

The main Beris Dam is founded on a sequence of thick bedded conglomerates and pebbly to fine grained sandstones with minor mudstone mapped as the Semanggol Formation of Triassic age. Ultrasonic pulse measurements show velocities of compressional and shear waves through the sandstones to increase with decreasing grain size; the pebbly sandstone with velocities of 2.210, and 5.171, km/s, and the coarse grained sandstone with velocities of 2.477, and 5.612, km/s, respectively. The medium grained sandstones have compressional and shear wave velocities of 2.457, and 5.793, km/s and the fine grained sandstones, velocities of 2.572, and 5.867 km/s, respectively. Dynamic elastic constants computed from the ultrasonic velocities also increase in values with decreasing grain size; Poisson’s ratio varying from 0.36 to 0.39, the modulus of elasticity from 35.076 to 48.210 GPa, the bulk modulus from 52.260 to 67.362 GPa and the modulus of rigidity from 12.637 to 17.468 GPa. Increasing velocities and elastic constants with decreasing grain size are considered to result from a denser arrangement of constituent grains as shown by increasing dry unit weights. Comparison with the results of an unconfined compression test on a fine grained sandstone indicate that the ultrasonic elastic constants are good approximations of static elastic constants.

Characterizing Riverbed Heterogeneity across Shifts in River Discharge through Temporal Changes in Electrical Resistivity

2020 ◽  
Vol 25 (4) ◽  
pp. 581-587
Author(s):  
Weston J. Koehn ◽  
Stacey E. Tucker-Kulesza ◽  
David R. Steward
Keyword(s):  
Electrical Resistivity ◽  
Temporal Changes ◽  
Coarse Grained ◽  
Arkansas River ◽  
Alluvial Deposits ◽  
Fine Grained ◽  
Surrounding Matrix ◽  
Aquifer Depletion ◽  
Fine Grained Soil ◽  
The Individual

The fluxes between groundwater and surface water play a significant role in quantifying water balance along stream reaches to continent scales. Changes in these dynamics are occurring due to aquifer depletion, where pre-development baseflow conditions have transitioned to losing conditions. This problem is studied along the Arkansas River in Western Kansas across a stream reach that transitions from near steady state to losing conditions, and contributes focused recharge to a depleting Ogallala Aquifer. Existing hydrologic data illustrates the lack of understanding they provide related to the control of fluxes exerted by alluvial deposits. Electrical resistivity imaging (ERI) surveys were conducted along this river transect to elucidate the dynamic hydrologic connection existing between the Arkansas River and underlying Arkansas Alluvial and Ogallala Aquifers. Temporal changes in ERI profiles are associated with the transient hydrologic conditions below the water-sediment interface, and complement the hydrogeologic interpretations of the individual ERI profiles. Additionally, fine grained soil inclusions may become revealed by temporal changes in resistivity due to differences in their water holding capacity relative to that of a surrounding matrix of coarser grained soil across changes in recharge. These findings corroborate the role of river-aquifer connectivity and riverbed heterogeneity on localized recharge through embedded assemblages of fine and coarse grained soils.

Texture of Al-Cu Alloys Deformed by ECAP

2005 ◽  
Vol 495-497 ◽  
pp. 851-856 ◽  
Author(s):  
Jan Kuśnierz ◽  
Marie Helene Mathon ◽  
Thierry Baudin ◽  
Zdzislaw Jasieński ◽  
Richard Penelle
Keyword(s):  
Grain Size ◽  
Aluminium Alloys ◽  
Superplastic Forming ◽  
Orientation Distribution ◽  
Coarse Grained ◽  
Fine Grained ◽  
Angular Pressing ◽  
Cu Alloys ◽  
Super Plastic ◽  
Short Time

Materials of ultra-fine grained microstructure (sub-micrometer grain size) exhibit large strength, hardness and ductility and also the increased toughness in comparison with conventional coarse-grained ones. In these materials also the super-plastic flow at lower temperatures is observed. This behaviour may be interesting when aluminium alloys like AlCuZr, used in superplastic forming, are considered. In the paper, the methods of preparing such materials by equal-channel angular pressing (ECAP) is proposed and the texture analysis, based on neutron diffraction pole figure measurements and calculated orientation distribution function of two alloys AlCu4SiMn and AlCu5AgMgZr is discussed. The influence of short time recrystallization is discussed in relation with TEM and SEM observations.

On: “Weak elastic anisotropy,” by L. Thomsen (GEOPHYSICS, 52, 1954–1966, October, 1986).

Geophysics ◽  
1988 ◽  
Vol 53 (4) ◽  
pp. 558-559 ◽  
Author(s):  
Franklyn K. Levin
Keyword(s):  
Elastic Constants ◽  
Vertical Velocity ◽  
Elastic Waves ◽  
Elastic Anisotropy ◽  
Transversely Isotropic ◽  
P Wave ◽  
Sh Waves ◽  
The Individual ◽  
Transversely Isotropic Solids ◽  
Isotropic Solids

In a paper whose importance seems to have escaped notice, Thomsen (1) derived equations that give the moveout velocities of P, SV, and SH-waves when solids are weakly transversely isotropic and (2) tabulated experimentally determined elastic constants for a large number of rocks, crystals, and a few other solids. For rocks, one of the constants, delta, differed from zero by as much as 0.73 and −0.27. Delta is the fraction by which P-wave moveout velocity deviates from the vertical velocity [Thomsen’s equation (27a)]. Although some deltas indicated deviations from the vertical velocity smaller than 1 or 2 percent, most were larger and positive. Until the publication of Thomsen’s data, most of us concerned with elastic waves traveling in earth sections that act as transversely isotropic solids because the sections consist of thin beds had assumed the individual beds were isotropic solids, all with the same Poisson’s ratios. That assumption results in a zero value for delta and a moveout velocity equal to the vertical velocity. The validity of the assumption is now doubtful.

scholarly journals First-principles study of the structural, electronic, and elastic properties of Sc2SiX (X=C, N)

2021 ◽  
Vol 67 (3 May-Jun) ◽  
pp. 500
Author(s):  
M. Mebrek ◽  
M. Berber ◽  
B. Doumi ◽  
A. Mokaddem
Keyword(s):  
Electronic Properties ◽  
Elastic Constants ◽  
First Principles ◽  
Formation Energy ◽  
Elastic Anisotropy ◽  
Surface Characteristics ◽  
Hexagonal Structure ◽  
Main Factors ◽  
The Individual ◽  
First Time

Using ab-initio calculations, we studied the structural, elastic, and electronic properties of Sc2SiX compounds with, (X=C, N). The negative formation energy and the positive cohesive energy indicate that these compounds are energetically stable and can be synthesized in normal conditions. Sc2SiC and Sc2SiN compounds are mechanically stable, estimated by the individual elastic constants. Elastic constants and modulus increase when C is substituted by N. The elastic anisotropy in Sc2SiC is high compared to Sc2SiN. Both nanolaminates are fragile in nature. Sc2SiC is more conductive than Sc2SiN. The calculated electron band structures and the density of states imply that the chemical bond in two compounds is a combination of covalent, ionic, and metallic nature. The main factors governing the electronic properties are the hybrid states Sc- 3d, Si-3p, and C -2p and the bond (p-d) stabilizes the structure. Fermi's surface characteristics have been studied for the first time, which are changed when replacing N by C. Based on the estimate of the total energy, we conclude that the replacement of C by N will lead to a stabilization of the hexagonal structure and a decrease of the metallic support.

Spatial variations in sediment systems

2009 ◽  
Author(s):  
John S. Gray ◽  
Michael Elliott
Keyword(s):  
Spatial Scales ◽  
Coarse Grained ◽  
Anthropogenic Effects ◽  
Individual Species ◽  
Physical Disturbance ◽  
Fine Grained ◽  
The Past ◽  
The Individual ◽  
General Physical

In this chapter the primary emphasis is on spatial scales of disturbances, and we will follow on from our earlier discussions on the mechanisms of competition and predation and the controversy over their importance in controlling species richness. Huston (1994) realized that the effects of competition, predation, and general physical disturbance were similar in that individuals were removed from the assemblage. We now show that there is a need to link these aspects with the tolerances of individual species, for example to determine in which of these cases the organisms are absent because the conditions now fall outside the optimal tolerance ranges. Thus we discuss disturbance as a general phenomenon which includes the effects of any processes that lead to a reduction in numbers of individuals and/or biomass. Disturbance includes physical disturbance as well as biological processes such as the effects of competition and predation on assemblages. The spatial scales covered range from micrometres to many hundreds of kilometres for the effects of bottom trawling, which is now considered to be one of the most serious and damaging threats to sediment habitats and assemblages. Disturbance effects caused by trawling and by pollution are considered in the following chapters. First, it is necessary to consider scale since many new insights have developed in the past few years of research. In the past couple of decades a new branch of ecology, landscape ecology, has developed, devoted to considering patterns over large areas, and a terminology of spatial scales has been defined. Grain is the first level of spatial resolution; it relates to the individual data unit and can be described as fine-grained to coarse-grained. Extent refers to the overall size of the study area. A map of 100 km2 and one of 100 000 km2 differ in extent by a factor of 1000. Grain and extent are illustrated in Fig. 6.1. A third component is lag, which is the betweensample distance. Figure 6.2 summarizes temporal and spatial scales of disturbances (modified from Zajac et al. 1998). The figure shows the main types of disturbances affecting soft-sediment systems, and separates them into natural and anthropogenic effects (see also Chapter 11, which indicates some of the management responses to these effects).

Pattern decomposition for residual stress analysis: a generalization taking into consideration elastic anisotropy and extension to higher-symmetry Laue classes

2017 ◽  
Vol 50 (4) ◽  
pp. 1011-1020 ◽  
Author(s):  
Peter Schoderböck ◽  
Peter Leibenguth ◽  
Michael Tkadletz
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Elastic Constants ◽  
Elastic Anisotropy ◽  
Hard Coatings ◽  
Titanium Carbonitride ◽  
X Ray ◽  
Residual Stress State ◽  
Pattern Decomposition ◽  
Decomposition Procedure

The residual stress state of ion-conducting layers (yttria stabilized zirconia) and protective hard coatings (α-aluminium oxide, titanium carbonitride) was investigated using X-ray diffraction techniques. Its evaluation within the tetragonal, trigonal and cubic phases present was performed by a whole powder pattern decomposition procedure according to Pawley. Going beyond previous work, the applied refinements directly include the influence of elastic anisotropy on the residual stress results. Starting from the single-crystal elastic coefficients, the X-ray elastic constants according to the Voigt and Reuss models were calculated. Finally, the Neerfeld–Hill model as a generalization was implemented to introduce thehkl-specific X-ray elastic constants for calculating the residual stress magnitude within the least-squares minimization routine. It was possible to resolve the residual stress state in stacked layers of different chemical and phase composition and to reproduce the results obtained by the classical χ- and ω-inclination sin2Ψ techniques.

Advanced Resonant-Ultrasound Spectroscopy for Studying Anisotropic Elastic Constants of Thin Films

2005 ◽  
Vol 875 ◽  
Author(s):  
Hirotsugu Ogi ◽  
Nobutomo Nakamura ◽  
Hiroshi Tanei ◽  
Masahiko Hirao
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Film Thickness ◽  
Elastic Constants ◽  
Elastic Anisotropy ◽  
Thickness Direction ◽  
Resonant Ultrasound Spectroscopy ◽  
Out Of Plane ◽  
Resonant Ultrasound ◽  
Anisotropic Elastic

AbstractThis paper presents two advanced acoustic methods for the determination of anisotropic elastic constants of deposited thin films. They are resonant-ultrasound spectroscopy with laser-Doppler interferometry (RUS/Laser method) and picosecond-laser ultrasound method. Deposited thin films usually exhibit elastic anisotropy between the film-growth direction and an in-plane direction, and they show five independent elastic constants denoted by C11,C33,C44,C66 and C13 when the x3 axis is set along the film-thickness direction. The former method determines four moduli except C44, the out-of-plane shear modulus, through free-vibration resonance frequencies of the film/substrate specimen. This method is applicable to thin films thicker than about 200 nm. The latter determines C33, the out-of-plane modulus, accurately bymeasuring the round-trip time of the longitudinal wave traveling along the film-thickness direction. This method is applicable to thin films thicker than about 20 nm. Thus, combination of these two methods allows us to discuss the elastic anisotropy of thin films. The results for Co/Pt superlattice thin film and copper thin film are presented.

Changes in Crystallographic Orientation Distribution during Superplastic Deformation in Aluminum Alloys

2016 ◽  
Vol 838-839 ◽  
pp. 72-77 ◽  
Author(s):  
Yoshimasa Takayama ◽  
Eizo Kimijima ◽  
Eiji Harunari ◽  
Hideo Watanabe
Keyword(s):  
Strain Rate ◽  
Crystallographic Orientation ◽  
Superplastic Deformation ◽  
Early Stage ◽  
Orientation Distribution ◽  
Electron Back Scatter Diffraction ◽  
Grain Structure ◽  
Coarse Grained ◽  
Fine Grained ◽  
Low Strain Rate

Changes in crystallographic orientation distribution during superplastic deformation in a fine-grained Al-Zn-Mg-Cu alloy and an Al-Mg-Mn alloy consisting of the coarse-grained surface and the fine-grained center layers have been reviewed in order to reveal contribution of dislocation slips to deformation. The strain rate and grain size dependences of the deformation behavior were examined by SEM/EBSD (scanning electron microscopy/ electron back scatter diffraction) analysis. Intragranular misorientation increases after deformation at high strain rates, presumably due to dislocation activity, while it was low in the specimen deformed at a low strain rate in the early stage of 35% strain. Progressive randomization of the initial texture was also found during deformation at the low strain rate. Further, grain structure and grain boundary character are analyzed in detail to discuss the deformation mechanism.

Sign in / Sign up

Export Citation Format

Share Document