| X-Ray Diffraction and Finite Element Study of Residual Stress Effects on Fatigue Crack Growth |
MAY 97 |
8 pages |
| Authors:
J. D. Almer; J. B. Cohen; K. R. McCallum; R. A. Winholtz; NORTHWESTERN UNIV EVANSTON IL
|
 | The combined techniques of microbeam x-ray diffraction and Finite Element (FE) analysis have been used to analyze the residual stresses resulting from an interference operation in 1080 steel. Both techniques showed the resulting stresses to be tensile, and accelerated growth rates were observed in fatigue cracks subsequently grown into this residual stress field. The growth rates also showed a clear sensitivity to applied stress intensity level. Through thickness residual stress ... |
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| Some Recent Results on Stresses in Thin Films and Precipitates |
OCT 92 |
20 pages |
| Authors:
J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Diffraction remains the premier tool for sampling the residual stresses in materials non destructively, the only one capable of determining the entire stress tensor, and with few assumptions. The technique has kept pace with the needs of researchers in the area of multiphase materials; now, the stresses can be separated into macro and micro components. The deviatoric macro and micro stress components and hydrostatic macrostress can be measured without knowledge ... |
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| Load Sharing of the Phases in 1080 Steel During Low-Cycle Fatigue |
92 |
|
| Authors:
R. A. Winholtz; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
 | By means of X-ray diffraction, the stress response of the individual phases in a 1080 steel were measured; specimens with pearlitic, spheroidal, and tempered martensitic microstructures were subjected to low-cycle fatigue and the stress-strain hysteresis loops were separated into components for the carbide and matrix phases; calculations of the microstresses formed by differential plastic deformation of the matrix and inclusions accurately model the spheroidite; measured microstresses in the pearlite are ... |
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| The Structure of G.P. Zones in an Al-Cu-Zn Alloy |
92 |
|
| Authors:
D. R. Haeffner; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL
|
| A crystal of Al-1.46 at pct.Cu-2.20 at pct.Zn was prepared by quenching and aging; effects of Cu and Zn in the diffuse scattering were separated using anomalous dispersion by measuring each respective absorption edge for diffuse scattering in absolute units at two different energies; analysis of scattering contrasts between these two conditions gave short range order for Al-Cu and Al-Zn pairs; computer simulation determined the orientation of Zn and Cu. ... |
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| Determining Stresses in Composites |
JUL 91 |
12 pages |
| Authors:
J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| The basic diffraction techniques for the stress tensor analysis are reviewed, with particular emphasis on what can be done without knowing the unstressed lattice parameters(s). Examples are given of the residual stresses in thin films, how to measure the bonding and yield stress in composites and separating the micro and macrostresses to examine load sharing between phases. In this paper the term composite includes thin films on substrates, and steel, ... |
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| Changes in the Macrostresses and Microstresses in Steel with Fatigue |
JUL 91 |
48 pages |
| Authors:
R. A. Winholtzd; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| The residual stresses in both the ferrite and cementite phases of fatigued 1080 steel specimens with pearlite, spheroidite, and tempered martensite microstructures were measured with x-ray diffraction giving both the macrostresses and the microstresses. Specimens with no initial stresses showed little changes with fatigue. Specimens with initial macrostresses and with initial microstresses showed fading of the stresses, the fading being the slowest for the strongest microstructure. Hydrostatic microstresses are present ... |
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| Materials Can be Stressed Out Too |
DEC 90 |
40 pages |
| Authors:
I. C. Noyan; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| 'Locked in' or residual stresses occur almost always in making and using materials, from computer chips and dental fillings to tanker hulls, pipe lines and aircraft. These stresses can sometimes improve the life of a manufactured item, but can also lead to catastrophic failure. |
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| Load Sharing of the Phases in 1080 Steel during Low Cycle Fatigue |
NOV 90 |
30 pages |
| Authors:
R. A. Winholtz; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| By means of x-ray diffraction, the stress response of the individual phases in a 1080 steel were measured. Specimens with pearlitic, spheroidal, and tempered martensitic microstructures were subjected to low cycle fatigue and the stress strain hysteresis loops were separated into components for the carbide and matrix phases. These results show that as the material yields in both tension and compression the carbides take a higher fraction of the load ... |
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| Load Sharing of the Phases in 1080 Steel During Low Cycle Fatigue |
90 |
|
| Authors:
R. A. Winholtz; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| By means of X-ray diffraction, the stress response of the individual phases i a 1080 steel were measured; specimens with pearlitic, spheroidal, and tempered martensitic microstructures were subjected to low cycle fatigue and the stress strain hysteresis loops were separated into components for the carbide and matrix phases; these results show that as the material yields in both tension and compression the carbides take a higher fraction of the load ... |
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| Separation of the Macro- and Micro-Stresses in Plastically Deformed 1080 Steel |
AUG 88 |
16 pages |
| Authors:
R. A. Winholtz; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The stress tensors were measured with x-ray diffraction in both the ferrite and cementite phases of a 1080 steel specimen deformed in uniaxial tension. The macro- and micro-stresses were separated for all the components of the stress tensors. All the components except the hydrostatic components of the micro-stresses could be determined without an accurate value of the unstressed lattice parameter. Tensile stresses were found in the cementite and compressive stresses ... |
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| The Use of X-Rays and Neutrons to Measure (Residual) Stress Elastic Constants |
JUL 87 |
21 pages |
| Authors:
P. J. Rudnik; A. D. Krawitz; D. G. Reichel; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| From this study, one can conclude that, for a sample without a large stress gradient, the diffraction elastic constants should not be dependent upon the radiation source which is used to measure them. Nor are they dependent upon whether uniaxial tension or four-point bending is used. This is, of course, just a beginning; future experiments must address the effects of a large stress gradient in the sample. This is necessary ... |
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| A Generalized Least-Squares Determination of Triaxial Stress States by X-Ray Diffraction and the Associated Errors |
JUL 87 |
|
| Authors:
R. A. Winholtz; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The determination of residual stresses via x-ray diffraction is briefly reviewed, with particular emphasis on the triaxial stress state. A new method is proposed for determining the general stress tensor, which considerably reduces the variances of the stresses due to counting statistics and gradients. The procedure involves a generalized least square solution of strains measured at vario us tilts of the x ray beam to the sampled and a set ... |
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| METHOD AND APPARATUS FOR THE 'ON-LINE' NONDESTRUCTIVE MEASUREMENT AND CONTROL OF GRAIN SIZE IN MATERIALS - PATENT 4,649,556 |
MAR 87 |
|
| Authors:
C. Rinik; J. B. Cohen; J. E. Hilliard
|
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| The Agglomeration of Point Defects in Transition Metal Monoxides |
87 |
|
| Authors:
E. Gartstein; M. Radler; T. O. Mason; J. B. Cohen
|
| Recent results on the diffuse scattering from single crystals of Fe sub 1-x O at high temperature reveal that the defect structure is in striking agreement with embedded cluster calculations by Ellis et al. The dominant defect is an imperfect 7:2 cluster. Mixtures of this and a larger complex (13:4) can explain the electrical properties. XANES studies of this oxide are in agreement with Ellis' theoretical work. However, in both ... |
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| RESIDUAL STRESS MEASUREMENTS OF A PLASMA-SPRAYED COATING SYSTEM USING SYNCHROTRON X-RAY RADIATION |
JUL 86 |
|
| Authors:
P. Georgopoulos; J. B. Cohen; H. Herman
|
| synchrotron x-ray radiation is used to determine the residual stress associated with the substrate surface beneath a thick plasma-sprayed al 203 coating. (author) |
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| Residual Stress Measurements of a Plasma Sprayed Coating System Using Synchrotron X-Ray Radiation |
FEB 86 |
|
| Authors:
P. Georgiopoulos; J. B. Cohen; H. Herman; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| Residual stresses have been measured for the first time in the substrate below a plasma coating of ceramic. The effect of the heating by the coating during application was detected. Keywords: Coatings; Residual Stresses; Plasma Coatings |
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| Profile Fitting in Residual Stress Determination |
AUG 85 |
|
| Authors:
T. J. Devine; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| Of major importance in the determination of residual stress via diffraction is the accuracy of the measurement of the scattering angle (2 thata p) of a Bragg peak. This determines the accuracy of the interplanar (d) spacing and hence the strain and stress. In the U.S., the most commonly accepted method of determining peak position is a parabolic fit near the top of a peak. (While a diffraction peak is ... |
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| Neutron Stress Measurements with a Position Sensitive Detector |
AUG 85 |
|
| Authors:
A. D. Krawitz; P. J. Rudnik; B. D. Butler; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| The feasibility of measuring residual and applied stresses with neutrons employing a position sensitive detector (PSD) is demonstrated. Measurements with both a small beam, to probe internal regions, and a large beam, for bulk sampling have been made. With such a detector collection of data is rapid compared to ordinary neutron collection methods. This detector allows more detailed sampling, smaller probe regions and possibly even study of time- dependent processes. ... |
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| The Measurement of Stresses in Composites |
AUG 85 |
|
| Authors:
J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| Although there is mounting interest in the measurement of stresses in composite materials after fabrication and/or use, few measurements to date have taken into account the three dimensional nature of the stress system in such materials. Most data gives only the net stress, that is the difference between principal stresses. This report develops a procedure for a more complete measurement (in a reasonable time), including the separation of macrostresses and ... |
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| Errors Due to Counting Statistics in the Triaxial Strain (Stress) Tensor Determined by Diffraction |
01 JUL 85 |
|
| Authors:
P. Rudnik; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| Knowledge of the errors in a diffraction measurement of residual strains and stresses is useful information, not only in its own right, but also because it permits automation of a measurement to an operator specified precision. There are three sources of these errors: (1) Instrumental effects; (2) Uncertainties in x-ray elastic constants; and (3) Errors in the diffraction peak position related to counting statistics. In this paper the errors are ... |
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| X-Ray Elastic Constants and Their Meaning for Al and Fe |
JUL 85 |
7 pages |
| Authors:
R. M. Zhong; I. C. Noyan; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| In the measurement of residual stresses via diffraction (using x-rays or neutrons) it is strains that are actually determined, by employing the interplanar spacing (d subscript hkl) of the (hkl) planes as an internal strain gauge. The change in this spacing is measured from the shift of diffraction peaks (and Bragg's law) at several orientations of the sample to the incident beam, and the resultant strains are converted to stresses ... |
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| X-Ray Diffraction Study of Changes in Stress/Strain Distributions during Fatigue of a Two-Phase Alloy |
FEB 85 |
|
| Authors:
I. C. Noyan; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| In annealed two-phase brass, push-pull fatigue at loads near the endurance limit produces residual stresses only in the softer majority alpha phase, not in Beta. These stresses are balanced between undeformed alpha-phase regions, and a small fraction of deformed alpha; the Beta phase is not involved in this balance. The uniform deformation produced by peening becomes inhomogeneous during fatigue, especially in the softer alpha-phase. This inhomogeneity of deformation is greater ... |
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| X-RAY DIFFRACTION STUDY OF CHANGES IN STRESS/STRAIN DISTRIBUTIONS DURING FATIGUE OF A TWO-PHASE ALLOY |
FEB 85 |
|
| Authors:
I. C. Noyan; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| in annealed two-phase brass, push-pull fatigue at loads near the endurance limit produces residual stresses only in the softer majority alpha phase, not in beta. these stresses are balanced between undeformed alpha-phase regions, and a small fraction of deformed alpha; the beta phase is not involved in this balance. the uniform deformation produced by peening becomes inhomogeneous during fatigue, especially in the softer alpha-phase. this inhomogeneity of deformation is greater ... |
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| An X-Ray Diffraction Study of the Residual Stress/Strain Distribution in Shot-Peened Two-Phase Brass |
JAN 85 |
|
| Authors:
I. C. Noyan; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| X-ray residual stress determination and line broadening analysis were used to study the deformation distributions existing in the surface layers of a shot-peened two-phase brass specimen. The results indicate inhomogeneous partitioning of the plastic strains between the alpha- beta-strains, as well as between the surface layers and the bulk. The microstresses, which occur due to differential deformation between alpha and beta strains, have a maximum in the beta-grains at the ... |
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| AN X-RAY DIFFRACTION STUDY OF THE RESIDUAL STRESS/STRAIN DISTRIBUTION IN SHOT-PEENED TWO-PHASE BRASS |
JAN 85 |
|
| Authors:
I. C. Noyan; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| x-ray residual stress determination and line broadening analysis were used to study the deformation distributions existing in the surface layers of a shot-peened two-phase brass specimen. the results indicate inhomogeneous partitioning of the plastic strains between the alpha - beta strains, as well as between the surface layers and the bulk. the microstresses, which occur due to differential deformation between alpha and beta strains, have a maximum in the beta-grains ... |
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| Effects of Fatigue on the G. P. Zones in Al-Zn Alloys |
16 JAN 1984 |
|
| Authors:
R. G. Pahl Jr.; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| Small-angle x-ray scattering has been applied to study the evolution and stability of G.P. zones in two Al-Zn alloys during fatigue, to provide statistically sound information on this process. In a 5.3 at pct Zn alloy containing zones with an average diameter of the normally sluggish coarsening was accelerated by fatigue at room temperature. In the same alloy with larger zones there is no growth, except near a fatigue crack. ... |
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| Size Distribution for G. P. Zones in Dilute Al-Zn Alloys |
09 JAN 1984 |
|
| Authors:
R. G. Pahl Jr.; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| The G.P. zone size distribution has been measured in dilute Al-Zn alloys via small-angle x-ray scattering. This distribution does not agree with current theories for the Ostwald ripening process. (Author) |
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| Local Atomic Arrangements in the Solid Solution Al-1.7 at.% Cu, at 793 K |
DEC 83 |
|
| Authors:
E. Matsubara; J. B. Cohen
|
| The absolute diffuse X-ray intensity, scattered from a crystal of Al- 1.7 at% Cu, was measured in the solid solution region at 793 K. This intensity was separated into terms associated with local order, and those due to displacements of atoms from the sites of the average lattice. Computer simulations with the measured short-range order parameters and for a pseudo- random alloy were compared. The actual alloy has few isolated ... |
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| The Measurement of Elastic Constants for the Determination of Stresses by X-Rays |
29 JUL 1983 |
16 pages |
| Authors:
K. Perry; I. C. Noyan; P. J. Rudnik; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| The equations for errors in the measurement of x-ray elastic constants are derived. An automated device for measuring these has been developed and tested. |
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| Determining Stresses in the Presence of Nonlinearities in Interplanar Spacing vs. SIN Squared PSI |
29 JUL 1983 |
|
| Authors:
I. C. Noyan; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| The physical meaning of non-linearities in d vs. sin sub 2 psi lines, encountered in X-ray measurements of surface residual stresses in polycrystalline materials is investigated. It is shown that when oscillations are present in any one reflection, switching to another reflection to obtain a straight line in d vs. sin sub 2 psi is feasible only under very special conditions. The authors also discuss the effect of quasi-homogeneous strain ... |
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| Changes in Residual Stress, Domain Size and Microstrain during Fatigue of 1008 Steel |
01 MAR 1983 |
|
| Authors:
H. K. Kuo; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| Changes in the positions and shapes of x-ray diffraction peaks have been examined after low-cycle and high-cycle strain-controlled fatigue of normalized and cold-worked 1008 steel. Measurements were made at and below the surface. Domain (mosaic) size is sometimes the major contributor to peak breadth, but sometimes it is controlled by microstrain, or by both quantities. Microstrains are larger after low-cycle fatigue than after high-cycle fatigue. The surface residual stress is ... |
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| Local Defect Arrays and Properties of Oxides |
28 FEB 1983 |
|
| Authors:
J. B. Cohen; D. E. Ellis; M. E. Fine; T. O. Mason; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This project was an interdisciplinary effort attempting to quantify the relationships between the electrical and magnetic properties of transition metal oxides and their local defect arrangements. Highly specialized x-ray techniques were applied to establish defect structures in materials where electrical properties or magnetic properties were also studied. Quantum theoretical modelling of defect structures was also initiated. |
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| The Structure of GP Zones in Al-Cu Alloys |
SEP 82 |
|
| Authors:
J. B. Cohen; P. Georgopoulos
|
| The mathematical model presented in MCIC-118022 is challenged. The existence of pure or nearly pure copper multilayers in Al-Cu is discussed. |
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| Residual Stresses and Sliding Wear |
25 MAY 1982 |
|
| Authors:
J. W. Ho; C. Noyan; J. B. Cohen; V. D. Khanna; Z. Eliezer; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| The residual stresses that develop during wear of SAE 1018 and 4340 steel have been examined. The entire three-dimensional stress tensor was obtained. A normal magnitude is too small to affect the wear rate. There are also significant shear stresses. The wear process rapidly alters any initial stress distribution produced by heat treatment or peening to such a degree that the wear rate is not affected by these stresses, unless ... |
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| Study of Extended X-Ray Absorption Fine Structure for Possible Use in Examining Local Atomic Arrangements in Oxides |
14 JAN 1982 |
|
| Authors:
C. Tang; P. Georgopoulos; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL
|
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| The Plastic Zone and Residual Stress near a Notch and a Fatigue Crack in HSLA Steel |
16 DEC 1981 |
|
| Authors:
W. H. Schlosberg; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| The plastic zone and residual stress around a notch under load and with the load removed, and around a fatigue crack (at the same stress intensity factor as for the notch) have been examined, with automated X-ray techniques and a microbeam. There is a good agreement between the measured plastic zone size and Hutchinson's theory for a work hardening material. Residual stresses exist well behind the tip, and vary with ... |
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| The Nature of Residual Stress and Its Measurement |
16 JUL 1981 |
|
| Authors:
I. C. Noyan; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| The origins of residual stress and changes during fatigue are discussed. A new mechanism for fading is proposed. Practical (destructive and non-destructive) methods for measuring this stress are critically reviewed. Each technique has major problems requiring further study, but acoustic, magnetic and x-ray methods are all poised for more widespread use. (Author) |
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| THE NATURE OF RESIDUAL STRESS AND ITS MEASUREMENT |
JUL 81 |
|
| Authors:
I. C. Noyan; J. B. Cohen
|
| the origins of residual stress and changes during fatigue are discussed. a new mechanism for fading is proposed. practical (destructive and non-destructive) methods for measuring this stress are critically reviewed. each technique has major problems requiring further study, but acoustic, magnetic and x-ray methods are all poised for more widespread use. (author) |
|
| The Structure of G.P. I Zones in Al-1.7 At.% Cu |
JUN 81 |
|
| Authors:
X. Auvray; P. Georgopoulos; J. B. Cohen
|
| Absolute X-ray intensities from an aged single crystal of Al-1.7 at.% Cu were analyzed to determine precipitation and distortion in the local structure. |
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| SOL-X: AN ON-LINE NONDESTRUCTIVE METHOD FOR MEASURING GRAIN SIZE WITH X- RAYS |
JUN 81 |
|
| Authors:
C. Rinik; J. E. Hilliard; J. B. Cohen
|
| it is shown that the grain size of commercial materials can be estimated by x-rays with little or no sample preparation. the method is readily automated and can be employed on-line, for example, in a rolling mill. (author) |
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| Changes in Residual Stresses during Tension Fatigue of Normalized and Peened SAE 1040 Steel. |
01 JAN 1981 |
|
| Authors:
M. McClinton; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| Appreciable compressive stresses develop during tensile fatigue (R=O) of normalized SAE 1040 steel, but only in or near regions of stress localization. These stresses develop in stages. After shot peening, the resultant compressive stresses are rapidly eliminated by tension-tension fatigue above the endurance limit, and replaced by tensile stresses. At lower stress levels the induced stresses fade quickly. (Author) |
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| X-Ray Diffraction Study of Zr(Ca, Y)O sub 2-x; The Disordered State |
1981 |
|
| Authors:
J. B. Cohen; M. Morinaga; J. Faber Jr; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
|
| The Structure of (Disordered) Stabilized Zirconias |
1981 |
|
| Authors:
J. B. Cohen; J. Faber Jr.; M. Morinaga; NORTHWESTERN UNIV EVANSTON IL
|
|
| EVALUATION OF (RESIDUAL) STRESSES IN TEXTURED CUBIC METALS |
MAY 80 |
|
| Authors:
h. dolle; J. B. Cohen
|
| in residual stress measurements with x-rays, the interplanar spacing is often assumed to alter linearly with the orientation of the reflecting grains with respect to the stress system; the calculation of the stresses is based on this assumption when either the well-known two-tilt or sin-2 psi methods are employed. but in materials with strong texture, large oscillations have sometimes been reported. a method proposed in the literature for evaluating stresses ... |
|
| The Defect Structure of VO sub x: Comparison between X-Ray and Electron Diffraction, |
12 MAR 1980 |
|
| Authors:
M. Morinaga; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL TECHNOLOGICAL INST
|
|
| residual stresses in ground steels |
JAN 80 |
|
| Authors:
h. dolle; J. B. Cohen
|
| a new x-ray method for the evaluation of three dimensional (residual) stress states is demonstrated by studies of the effect of grinding on armco iron and a medium carbon steel. although the penetration depth of the cr-radiation employed in this study is only 5 micrometers, there is evidence of residual stresses normal to the surface (normal and shear components). in the past it has been assumed that these stress components ... |
|
| THE MEASUREMENT OF RESIDUAL STRESSES BY X-RAY DIFFRACTION TECHNIQUES |
80 |
|
| Authors:
M. R. James; J. B. Cohen
|
| the need to consistently monitor and preserve the strength characteristics of materials during manufacture and service, coupled with advanced design techniques utilizing a greater percentage of the available strength of such materials has necessitated rapid advances in the use of nondestructive testing, and characterization of residual stresses in particular. in response to this need, important developments in equipment and measuring techniques and a greater understanding of the theoretical background have ... |
|
| X-Ray Diffraction Study of Zr(Ca,Y)O2-x. II. Local Ionic Arrangements, |
26 OCT 1979 |
|
| Authors:
M. Morinaga; J. B. Cohen; J. Faber Jr; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
|
| Residual Stresses in Ground Steels. |
13 JUN 1979 |
|
| Authors:
H. Doelle; J. B. Cohen; NORTHWESTERN UNIV EVANSTON IL DEPT OF MATERIALS SCIENCE
|
| A new x-ray method for the evaluation of three dimensional (residual) stress states is demonstrated by studies of the effect of grinding on Armco-iron and a medium carbon steel. Although the penetration depth of the Cr-radiation employed in this study is only 5 microns, there is evidence of residual stresses normal to the surface (normal and shear components). In the past it has been assumed that these stress components can ... |
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| STRESS ANALYSIS FROM POWDER DIFFRACTION PATTERNS |
JUN 79 |
|
| Authors:
J. B. Cohen; h. dolle; M. R. James
|
| a brief review of the method of measuring residual stresses in polycrystalline materials with x-rays is given. the effect of counting statistics on precision is discussed as well as factors that affect accuracy. beam penetration, stress gradients, and the form of the stress tensor can each seriously affect accuracy, if traditional methods are employed, and practical procedures to deal with such situations are outlined. (author) |
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Reports by Author
