scholarly journals A modified X-ray diffraction method to measure residual normal and shear stresses of machined surfaces

2022 ◽  
Author(s):  
Quanshun Luo
Keyword(s):  
Shear Stress ◽  
Normal Stress ◽  
New Method ◽  
Shear Stresses ◽  
X Ray Diffraction ◽  
Tin Coating ◽  
New Approach ◽  
X Ray ◽  
Residual Shear Stress ◽  
Normal And Shear Stresses

AbstractX-ray diffraction has been widely used in measuring surface residual stresses. A drawback of the conventional d ~ sin2ψ method is the increased uncertainty arising from sin2ψ splitting when a significant residual shear stress co-exists with a residual normal stress. In particular, the conventional method can only be applied to measure the residual normal stress while leaving the residual shear stress unknown. In this paper, we propose a new approach to make simultaneous measurement of both residual normal and shear stresses. Theoretical development of the new approach is described in detail, which includes two linear regressions, $$\frac{{d}_{\psi }+ {d}_{-\psi }}{2}$$ d ψ + d - ψ 2 ~sin2ψ and {dψ-d-ψ} ~ sin(2ψ), to determine the residual normal and shear stresses separately. Several samples were employed to demonstrate the new method, including turning-machined and grinding-machined cylindrical bars of a high strength steel as well as a flat sample of magnetron sputtered TiN coating. The machined samples were determined to have residual compressive normal stresses at both the axial and hoop directions as well as various scales of residual shear stresses. The TiN coating showed a high scale of residual compressive (normal) stress whereas the measured residual shear stress was extremely low. The new method showed significantly increased precision as compared to the conventional d ~ sin2ψ method.

X-ray measurement of triaxial residual stress on machined surfaces by the cosα method using a two-dimensional detector

2018 ◽  
Vol 51 (5) ◽  
pp. 1329-1338 ◽  
Author(s):  
Keisuke Tanaka
Keyword(s):  
Normal Stress ◽  
New Method ◽  
Shear Stresses ◽  
Plane Shear ◽  
X Ray ◽  
Plane Normal ◽  
Out Of Plane ◽  
Cutting Direction ◽  
Machined Surfaces

In recent years, the cosα method has attracted engineers as a new method of X-ray stress measurement using the whole Debye–Scherrer (D–S) ring recorded on a two-dimensional detector. The principle of the cosα method was first proposed by Taira, Tanaka & Yamasaki [J. Soc. Mater. Sci. Jpn, (1978),27, 251–256] for in-plane biaxial stress analysis and later extended by Sasaki and co-workers [Sasaki & Hirose (1995).Trans. Jpn Soc. Mech. Eng. Part A,61, 2288–2295; Sasaki, Takahashi, Sasaki & Kobayashi (2009).Trans. Jpn Soc. Mech. Eng. Part A,75, 219–227] to the triaxial state of stress. The method proposed by Sasaki and co-workers utilizes several D–S rings taken at different incident angles of X-rays in order to determine triaxial stresses. In the present paper, the cosα method was applied to measure triaxial residual stresses of uni-directionally machined surfaces of a carbon steel made by grinding, milling and planing. A recommended procedure for experimental measurements of in-plane normal and shear stresses and out-of-plane shear stress is proposed, together with a new method for determination of the out-of-plane normal stress. The tilt angle of X-ray incidence for stress determination is recommended to be larger than 35°, where the stress constant is low and the stress sensitivity is high. Normal incidence is recommended for the determination of out-of-plane shear stresses. The out-of-plane shear stress along the cutting direction was characteristic of uni-directionally machined surfaces and increased with cutting severity in the order of grinding, milling and planing. The in-plane normal stress was compressive for ground and milled surfaces, and the magnitude of compression was larger in the direction perpendicular to the cutting direction. On the basis of the stress values measured under different tilt angles, it is suggested that the magnitude of in-plane normal residual stress increases near the surface. The out-of-plane normal stress determined by the new method indicated a small compression.

scholarly journals Numerical Analysis of Shear and Particle Crushing Characteristics in Ring Shear System Using the PFC2D

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 229
Author(s):  
Sueng-Won Jeong ◽  
Kabuyaya Kighuta ◽  
Dong-Eun Lee ◽  
Sung-Sik Park
Keyword(s):  
Shear Stress ◽  
Numerical Analysis ◽  
Normal Stress ◽  
Numerical Results ◽  
Particle Flow Code ◽  
Shear Stresses ◽  
Particle Crushing ◽  
Ring Shear ◽  
Peak Shear Stress ◽  
Residual Shear Stress

The shear and particle crushing characteristics of the failure plane (or shear surface) in catastrophic mass movements are examined with a ring shear apparatus, which is generally employed owing to its suitability for large deformations. Based on results of previous experiments on waste materials from abandoned mine deposits, we employed a simple numerical model based on ring shear testing using the particle flow code (PFC2D). We examined drainage, normal stress, and shear velocity dependent shear characteristics of landslide materials. For shear velocities of 0.1 and 100 mm/s and normal stress (NS) of 25 kPa, the numerical results are in good agreement with those obtained from experimental results. The difference between the experimental and numerical results of the residual shear stress was approximately 0.4 kPa for NS equal to 25 kPa and 0.9 kPa for NS equal to 100 kPa for both drained and undrained condition. In addition, we examined particle crushing effect during shearing using the frictional work concept in PFC. We calculated the work done by friction at both peak and residual shear stresses, and then used the results as crushing criteria in the numerical analysis. The frictional work at peak and the residual shear stresses was ranged from 303 kPa·s to 2579 kPa·s for given drainage and normal stress conditions. These results showed that clump particles were partially crushed at peak shear stress, and further particle crushing with respect to the production of finer in shearing was recorded at residual shear stress at the shearing plane.

Normal fluid stresses are prevalent in rotary ventricular assist devices: A computational fluid dynamics analysis

2018 ◽  
Vol 41 (11) ◽  
pp. 738-751 ◽  
Author(s):  
Dominica PY Khoo ◽  
Andrew N Cookson ◽  
Harinderjit S Gill ◽  
Katharine H Fraser
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Shear Stress ◽  
Normal Stress ◽  
Ventricular Assist Devices ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Ventricular Assist ◽  
Assist Devices ◽  
Normal And Shear Stresses

Despite the evolution of ventricular assist devices, ventricular assist device patients still suffer from complications due to the damage to blood by fluid dynamic stress. Since rotary ventricular assist devices are assumed to exert mainly shear stress, studies of blood damage are based on shear flow experiments. However, measurements and simulations of cell and protein deformation show normal and shear stresses deform, and potentially damage, cells and proteins differently. The aim was to use computational fluid dynamics to assess the prevalence of normal stress, in comparison with shear stress, in rotary ventricular assist devices. Our calculations showed normal stresses do occur in rotary ventricular assist devices: the fluid volumes experiencing normal stress above 10 Pa were 0.011 mL (0.092%) and 0.027 mL (0.39%) for the HeartWare HVAD and HeartMate II (HMII), and normal stresses over 100 Pa were present. However, the shear stress volumes were up to two orders of magnitude larger than the normal stress volumes. Considering thresholds for red blood cell and von Willebrand factor deformation by normal and shear stresses, the fluid volumes causing deformation by normal stress were between 2.5 and 5 times the size of those causing deformation by shear stress. The exposure times to the individual normal stress deformation regions were around 1 ms. The results clearly show, for the first time, that while blood within rotary ventricular assist devices experiences more shear stress at much higher magnitudes as compared with normal stress, there is sufficient normal stress exposure present to cause deformation of, and potentially damage to, the blood components. This study is the first to quantify the fluid stress components in real blood contacting devices.

A New Approach for Determining Epilayer Strain Relaxation and Composition Through High Resolution X-Ray Diffraction

1995 ◽  
Vol 379 ◽  
Author(s):  
K. M. Matney ◽  
M.S. Goorsky
Keyword(s):  
High Resolution ◽  
Small Angle ◽  
Experimental Error ◽  
Strain Relaxation ◽  
New Method ◽  
X Ray Diffraction ◽  
New Approach ◽  
X Ray ◽  
First Order ◽  
Ray Geometry

ABSTRACTWe developed a new method of determining epilayer relaxation (along one direction) and composition using a symmetric and any single asymmetric high resolution x-ray diffraction scan. The previous use of small angle approximations can be very detrimental to calculated results and should be avoided. This new method does not employ small angle approximations or first order Taylor approximations, producing accurate results. The effect of x-ray geometry (glancing incident versus glancing exit) on the analysis of epilayer composition and strain is also reviewed. It is also shown that the glancing exit geometry is generally less susceptible to experimental error.

A new method for the identification and quantification of magnetite–maghemite mixture using conventional X-ray diffraction technique

Talanta ◽  
2012 ◽  
Vol 94 ◽  
pp. 348-352 ◽  
Author(s):  
Wonbaek Kim ◽  
Chang-Yul Suh ◽  
Sung-Wook Cho ◽  
Ki-Min Roh ◽  
Hanjung Kwon ◽  
...  
Keyword(s):  
New Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Identification And Quantification

scholarly journals Exploiting superspace to clarify vacancy and Al/Si ordering in mullite

IUCrJ ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 497-509 ◽  
Author(s):  
Paul Benjamin Klar ◽  
Iñigo Etxebarria ◽  
Gotzon Madariaga
Keyword(s):  
Density Functional ◽  
X Ray Diffraction ◽  
Intrinsic Structure ◽  
Functional Theory ◽  
New Approach ◽  
X Ray ◽  
Vacancy Ordering ◽  
Harmonic Modulation ◽  
First Time

Synchrotron single-crystal X-ray diffraction has revealed diffuse scattering alongside sharp satellite reflections for different samples of mullite (Al4+2xSi2−2xO10−x). Structural models have been developed in (3+1)-dimensional superspace that account for vacancy ordering and Al/Si ordering based on harmonic modulation functions. A constraint scheme is presented which explains the crystal-chemical relationships between the split sites of the average structure. The modulation amplitudes of the refinements differ significantly by a factor of ∼3, which is explained in terms of different degrees of ordering,i.e.vacancies follow the same ordering principle in all samples but to different extents. A new approach is applied for the first time to determine Al/Si ordering by combining density functional theory with the modulated volumes of the tetrahedra. The presence of Si–Si diclusters indicates that the mineral classification of mullite needs to be reviewed. A description of the crystal structure of mullite must consider both the chemical composition and the degree of ordering. This is of particular importance for applications such as advanced ceramics, because the physical properties depend on the intrinsic structure of mullite.

scholarly journals Controlled Growth of CdS Nanostep Structured Arrays to Improve Photoelectrochemical Performance

2020 ◽  
Vol 8 ◽  
Author(s):  
Jiangang Jiang ◽  
He Wang ◽  
Hongchang An ◽  
Guangyuan Du
Keyword(s):  
Tin Oxide ◽  
Energy Conversion Efficiency ◽  
Photoelectrochemical Cells ◽  
X Ray Diffraction ◽  
Reaction Parameters ◽  
Photoelectrochemical Performance ◽  
New Approach ◽  
Phase Purity ◽  
X Ray ◽  
Straight Rod

CdS nanostep-structured arrays were grown on F-doped tin oxide-coated glasses using a two-step hydrothermal method. The CdS arrays consisted of a straight rod acting as backbone and a nanostep-structured morphology on the surface. The morphology of the samples can be tuned by varying the reaction parameters. The phase purity, morphology, and structure of the CdS nanostep-structured arrays were characterized by X-ray diffraction and field emission scanning electron microscopy. The light and photoelectrochemical properties of the samples were estimated by a UV-Vis absorption spectrum and photoelectrochemical cells. The experimental results confirmed that the special nanostep structure is crucial for the remarkable enhancement of the photoelectrochemical performance. Compared with CdS rod arrays, the CdS nanostep-structured arrays showed increased absorption ability and dramatically improved photocurrent and energy conversion efficiency. This work may provide a new approach for improving the properties of photoelectrodes in the future.

A new approach to synchrotron energy-dispersive X-ray diffraction computed tomography

2012 ◽  
Vol 19 (4) ◽  
pp. 471-477 ◽  
Author(s):  
Olivier Lazzari ◽  
Christopher K. Egan ◽  
Simon D. M. Jacques ◽  
Taha Sochi ◽  
Marco Di Michiel ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Energy Dispersive ◽  
X Ray Diffraction ◽  
New Approach ◽  
X Ray
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