New Advantages in Soft X-ray Stress Measurement and Triaxial Analysis of Nonuniform Stress States

1994 ◽  
pp. 279-289 ◽  
Author(s):  
H. Wern ◽  
L. Suominen
Keyword(s):  
Stress Measurement ◽  
Nonuniform Stress ◽  
X Ray ◽  
Stress States

scholarly journals Statistical analysis of the reproducibility of residual stress measurements in cold extruded parts

2021 ◽  
Author(s):  
Fabian Jaeger ◽  
Alessandro Franceschi ◽  
Holger Hoche ◽  
Peter Groche ◽  
Matthias Oechsner
Keyword(s):  
Residual Stress ◽  
Statistical Analysis ◽  
Stress Measurement ◽  
Industrial Applications ◽  
Cold Extrusion ◽  
X Ray Diffraction ◽  
Forming Process ◽  
X Ray ◽  
Stress States ◽  
Key Aspects

AbstractCold extruded components are characterized by residual stresses, which originate from the experienced manufacturing process. For industrial applications, reproducibility and homogeneity of the final components are key aspects for an optimized quality control. Although striving to obtain identical deformation and surface conditions, fluctuation in the manufacturing parameters and contact shear conditions during the forming process may lead to variations of the spatial residual stress distribution in the final product. This could lead to a dependency of the residual stress measurement results on the relative axial and circumferential position on the sample. An attempt to examine this problem is made by the employment of design of experiments (DoE) methods. A statistical analysis of the residual stress results generated through X-Ray diffraction is performed. Additionally, the ability of cold extrusion processes to generate uniform stress states is analyzed on specimens of austenitic stainless steel 1.4404 and possible correlations with the pre-deformed condition are statistically examined. Moreover, the influence of the coating, consisting of oxalate and a MoS2 based lubricant, on the X-Ray diffraction measurements of the surface is investigated.

Study of Consistency between Two-Dimensional, sin2ψ, cosα and Fourier Transformation Methods for X-Ray Residual Stress Measurement by Debye Ring Simulation

2018 ◽  
Vol 941 ◽  
pp. 2407-2412 ◽  
Author(s):  
Muneyuki Imafuku ◽  
Yuki Ishikawa
Keyword(s):  
Stress Measurement ◽  
Axial Stress ◽  
Two Dimensional ◽  
X Ray ◽  
Debye Ring ◽  
Analysis Theory ◽  
Strain Relationship ◽  
Reverse Analysis ◽  
Stress States ◽  
Transformation Methods

We investigated the consistency of four methods by analyzing the distorted Debye rings with various stress states. Firstly, the distorted Debye rings were generated under various uni-, bi-and tri-axial stress states by using the fundamental stress-strain relationship in two dimensional X-ray stress analysis theory. Secondly, we performed reverse analysis of stress states in the frameworks of sin2ψ and cosα methods from the simulated Debye rings. Moreover, the profiles of simulated Debye rings were Fourier transformed and the stress states were calculated in accordance with the obtained 1st and 2nd order Fourier coefficients. As a result, it was confirmed that all these methods provide the same stress values. That is to say, all these methods are consistent. Therefore, we can guarantee the validity of choosing any appropriate method considering the geometrical restrictions of experiment.

Study on the Statistical Errors in X-Ray Stress Measurement with Two-Dimensional Detector

2018 ◽  
Vol 941 ◽  
pp. 2373-2377
Author(s):  
Shoichi Ejiri ◽  
Hiroaki Ohba ◽  
Toshihiko Sasaki
Keyword(s):  
Conventional Method ◽  
Measurement Errors ◽  
Stress Measurement ◽  
Statistical Error ◽  
Polycrystalline Materials ◽  
Two Dimensional ◽  
X Ray ◽  
Measured Stress ◽  
Stress States ◽  
Basic Equations

The sin2 ψ method [1] is conventionally used well as how to measure non-destructively the residual strain and stress states of polycrystalline materials by X-ray diffraction. In the conventional method, there are Dölle-Hauk method [2] and Winholz-Cohen least squares analysis [3] as the determinations of the strain and stress states for limiting the influence of measurement errors. Many researches are made about the statistical error in those methods. In recent years, use of the X-ray stress measurements with two-dimensional detector from the conventional method is spreading. One of the measurements is called the cos α method. The measurement errors have attracted a great deal of attention for users as the spreads. Therefore, the basic equations and determinations of the strain and stress states are examined. The confidence intervals of measured stress by the cos α method. The research and development is performed for the the cos α method which took the influence of measurement errors into consideration.

New Advantages in Soft X-Ray Stress Measurement and Triaxial Analysis of Nonuniform Stress States

1993 ◽  
Vol 37 ◽  
pp. 279-289
Author(s):  
H. Wem ◽  
L. Suominen
Keyword(s):  
Stress Analysis ◽  
Stress Measurement ◽  
Strain Tensor ◽  
Self Control ◽  
Data Sets ◽  
X Ray ◽  
Stress States ◽  
Measurement And Evaluation

AbstractConventional stress analysis with diffraction techniques is based on the equations of continuum mechanics, but only few materials encountered in X-ray stress analysis satisfy this assumption. In this paper, a new method is formulated yielding quantitative strain tensor fixed to the specimen coordinates. The method enables independent in-situ determination of Poisson's ratio which serves as a self control mechanism for measurement and evaluation. The analysis has been extended from flat to curved surfaces. Thus an exact analysts of spherical or cylindrical shaped specimens is now possible. The method has the capability to evaluate stress tensor and stress free lattice spacing at the surface as well as their variation with depth. This is demonstrated by two experimental data sets.

scholarly journals Spatially Resolved Forming Mechanisms Detection in Single Point Incremental Forming Using Synchrotron Based Texture Analysis

2021 ◽  
Author(s):  
Mateus Dobecki ◽  
Alexander Poeche ◽  
Walter Reimers
Keyword(s):  
Texture Analysis ◽  
Incremental Forming ◽  
Single Point ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Forming Mechanism ◽  
Spatially Resolved ◽  
Step Down ◽  
Stress States

AbstractDespite the ongoing success of understanding the deformation states in sheets manufactured by single-point incremental forming (SPIF), the unawareness of the spatially resolved influence of the forming mechanisms on the residual stress states of incrementally formed sheet metal parts impedes their application-optimized use. In this study, a well-founded experimental proof of the occurring forming mechanisms shear, bending and stretching is presented using spatially resolved, high-energy synchrotron x-ray diffraction-based texture analysis in transmission mode. The measuring method allows even near-surface areas to be examined without any impairment of microstructural influences due to tribological reactions. The depth-resolved texture evolution for different sets of forming parameters offers insights into the forming mechanisms acting in SPIF. Therefore, the forming mechanisms are triggered explicitly by adjusting the vertical step-down increment Δz for groove, plate and truncated cone geometries. The texture analysis reveals that the process parameters and the specimen geometries used lead to characteristic changes in the crystallites’ orientation distribution in the formed parts due to plastic deformation. These forming-induced reorientations of the crystallites could be assigned to the forming mechanisms by means of defined reference states. It was found that for groove, plate and truncated cone geometries, a decreasing magnitude of step-down increments leads to a more pronounced shear deformation, which causes an increasing work hardening especially at the tool contact area of the formed parts. Larger step-down increments, on the other hand, induce a greater bending deformation. The plastic deformation by bending leads to a complex stress field that involves alternating residual tensile stresses on the tool and residual compressive stresses on the tool-averted side incrementally formed sheets. The present study demonstrates the potential of high-energy synchrotron x-ray diffraction for the spatially resolved forming mechanism research in SPIF. Controlling the residual stress states by optimizing the process parameters necessitates knowledge of the fundamental forming mechanism action.

scholarly journals The X Ray Stress Measurement of Super-Duraimin under Tensile and Compressive Stress.

1944 ◽  
Vol 10 (38-1) ◽  
pp. 17-22
Author(s):  
Toshio NISHIHARA ◽  
Kohei KOZIMA ◽  
Shuzi TAIRA ◽  
Yutaro KOSAKA ◽  
Takeo TOMIYASU
Keyword(s):  
Compressive Stress ◽  
Stress Measurement ◽  
X Ray

Sensitivity of Macro- and Micro-Residual Stress States of Steel Surfaces to Thermal Influences Caused by Grinding Burn and Laser Treatments

2013 ◽  
Vol 768-769 ◽  
pp. 412-419
Author(s):  
Bernd Eigenmann ◽  
Antje Zösch ◽  
Martin Seidel
Keyword(s):  
Residual Stress ◽  
Threshold Values ◽  
Materials Properties ◽  
X Ray ◽  
Grinding Burn ◽  
Laser Treatments ◽  
Annealing Effects ◽  
Calibration Samples ◽  
Steel Surfaces ◽  
Stress States

Thermal influences, introduced intentionally or unintentionally do have significant effects on surfaces of steel components. Materials properties are reduced by annealing effects or even re-hardening zones can occur. Grinding, one of the most important technological processes for preci-sion manufacturing of hardened steel components, is an important source of thermal influences to steel surfaces. In pronounced cases, these influences are referred to as grinding burn. They are known as possible reasons for gray stains as well as development of cracks and pittings on heavy-duty gears and on roller bearings. The basic effect of thermal influences on the material is a change of the macro- and micro-residual stress states. Therefore, the knowledge of these residual stress states is of fundamental importance. The paper treats the mechanisms of grinding which can lead to thermal influences. Some characteristic appearances of grinding burn are shown and characterized by X-ray macro- and micro residual stress determinations. It is shown that defined laser treatments can be used to create reproducible thermal influences similar to grinding burn. Their effects are also characterized by X-ray residual stress measurements. The sensitivities of X-ray and metallographical investigations are compared. Defined laser traces are proposed as calibration samples for magnetic and eddy current measurements which allow to determine threshold values for the actual apparatus and measuring problem.

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