scholarly journals Spatial Internal Material Load and Residual Stress Distribution Evolution in Synchrotron In Situ Investigations of Deep Rolling

2020 ◽  
Vol 4 (1) ◽  
pp. 3
Author(s):  
Heiner Meyer ◽  
Jérémy Epp
Keyword(s):  
Residual Stress ◽  
Synchrotron Radiation ◽  
Rolling Process ◽  
European Synchrotron Radiation Facility ◽  
Von Mises Stress ◽  
Deep Rolling ◽  
Static Indentation ◽  
Material Load ◽  
Von Mises

Mechanical loading scenarios, comparable to a deep rolling process, were reproduced in static indentation experiments on AISI 4140H steel samples with a cylindrical deep rolling tool and investigated in situ with synchrotron radiation at the European Synchrotron Radiation Facility (ESRF) on beamline ID11. Through the use of spatially resolved diffraction data, two-dimensional (2D) equivalent von Mises stress maps were recorded during loading and after unloading. The material modifications were analyzed in the material below the contact zone for different loading conditions. It was demonstrated that the characteristics of internal material load and residual stress distributions can be evaluated through data fitting and the effect of the applied force could be linked to the stress fields by an empirical model. The experimental values were then compared to a contact mechanics approach in order to analyze the correlation between the theoretical maximum loading stresses and the stored elastic residual stresses remaining by considering the dissipation of a certain amount of energy through plastic deformation.

scholarly journals In Situ X-ray Diffraction Analysis of Stresses during Deep Rolling of Steel

2018 ◽  
Vol 2 (4) ◽  
pp. 20 ◽  
Author(s):  
Heiner Meyer ◽  
Jérémy Epp
Keyword(s):  
Plastic Deformation ◽  
Synchrotron Radiation ◽  
Residual Stresses ◽  
Contact Point ◽  
Stress Fields ◽  
Deep Rolling ◽  
2D Strain ◽  
Material State ◽  
Material Load

Residual stresses originating from elasto-plastic deformation during mechanical processing can be analyzed post-process with various known methods. A new measurement method to measure and evaluate the strain and stress fields in situ under the contact point during a deep rolling process was developed to describe the dependence of the residual stresses from the internal material load. Using synchrotron radiation at European Synchrotron Radiation Facility (ESRF) (ID11), diffraction measurements were performed in transmission geometry during dynamical loading with different process parameters. The strain and stress fields were analyzed with high spatial resolution in an 8 mm × 4 mm area around the contact point during the process using a 13-mm tungsten carbide roller on samples of AISI 4140H steel. Fast data acquisition allowed the reconstruction of full two-dimensional (2D) strain and stress maps. These could be used to determine the response from the initial material state in front of the roller to the mechanically loaded region with plastic deformation up to the processed material with the resulting residual stresses. This comprehensive analysis was then used to link the internal material load with the resulting residual stresses in the final material state.

scholarly journals A large-solid-angle X-ray Raman scattering spectrometer at ID20 of the European Synchrotron Radiation Facility

2017 ◽  
Vol 24 (2) ◽  
pp. 521-530 ◽  
Author(s):  
S. Huotari ◽  
Ch. J. Sahle ◽  
Ch. Henriquet ◽  
A. Al-Zein ◽  
K. Martel ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Raman Scattering ◽  
Solid Angle ◽  
European Synchrotron Radiation Facility ◽  
Electronic Excitations ◽  
Raman Scattering Spectroscopy ◽  
X Ray ◽  
Area Detector ◽  
Spectroscopic Tool

An end-station for X-ray Raman scattering spectroscopy at beamline ID20 of the European Synchrotron Radiation Facility is described. This end-station is dedicated to the study of shallow core electronic excitations using non-resonant inelastic X-ray scattering. The spectrometer has 72 spherically bent analyzer crystals arranged in six modular groups of 12 analyzer crystals each for a combined maximum flexibility and large solid angle of detection. Each of the six analyzer modules houses one pixelated area detector allowing for X-ray Raman scattering based imaging and efficient separation of the desired signal from the sample and spurious scattering from the often used complicated sample environments. This new end-station provides an unprecedented instrument for X-ray Raman scattering, which is a spectroscopic tool of great interest for the study of low-energy X-ray absorption spectra in materials under in situ conditions, such as in operando batteries and fuel cells, in situ catalytic reactions, and extreme pressure and temperature conditions.

scholarly journals Elasto-plastic analysis of the contact region between a rigid ellipsoid and a semi-flat surface

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401879739 ◽  
Author(s):  
Pengyang Li ◽  
Lingxia Zhou ◽  
Fangyuan Cui ◽  
Quandai Wang ◽  
Meiling Guo ◽  
...  
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Plastic Strain ◽  
Contact Pressure ◽  
Contact Region ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Effective Plastic Strain ◽  
Normal Forces ◽  
Von Mises

When the load acting on a mechanical structure is greater than the yield strength of the material, the contact surface will undergo plastic deformation. Cumulative plastic deformation has an important influence on the lifespan of mechanical parts. This article presents a three-dimensional semi-analytical model based on the conjugate gradient method and fast Fourier transform algorithm, with the aim of studying the characteristic parameters of the contact region between a rigid ellipsoid and elasto-plastic half-space. Moreover, normal forces and tangential traction were considered, as well as the contact pressure resulting from various sliding speeds and friction coefficients. The contact pressure, effective plastic strain, von Mises stress, and residual stress were measured and shown to increase with increasing sliding velocity. Finally, when the friction coefficient, contact pressure, and effective plastic strain are increased, the von Mises stress is also shown to increase, whereas the residual stress decreases.

scholarly journals A Finite Element Study of the Residual Stress and Deformation in Hemispherical Contacts

2005 ◽  
Vol 127 (3) ◽  
pp. 484-493 ◽  
Author(s):  
Robert Jackson ◽  
Itti Chusoipin ◽  
Itzhak Green
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Yield Criterion ◽  
Contact Region ◽  
Element Model ◽  
Von Mises Stress ◽  
Contact Radius ◽  
Perfectly Plastic ◽  
Von Mises

This work presents a finite element model (FEM) of the residual stresses and strains that are formed after an elastoplastic hemispherical contact is unloaded. The material is modeled as elastic perfectly plastic and follows the von Mises yield criterion. The FEM produces contours for the normalized axial and radial displacements as functions of the removed interference depth and location on the surface of the hemisphere. Contour plots of the von Mises stress and other stress components are also presented to show the formation of the residual stress distribution with increasing plastic deformation. This work shows that high residual von Mises stresses appear in the material pileup near the edge of the contact area after complete unloading. Values are defined for the minimum normalized interference, that when removed, results in plastic residual stresses. This work also defines an interference at which the maximum residual stress transitions from a location below the contact region and along the axis of symmetry to one near to the surface at the edge of the contact radius (within the pileup).

Numerical Simulation of Thermal/Mechanical Coupling in Laser Transmission Microjoining of PET and Titanium

2010 ◽  
Vol 160-162 ◽  
pp. 1118-1125 ◽  
Author(s):  
Zhen Kai Xu ◽  
Hui Xia Liu ◽  
Pin Li ◽  
Xin Hua Song ◽  
Kai Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Laser Beam ◽  
Dissimilar Materials ◽  
Good Combination ◽  
Von Mises Stress ◽  
Mechanical Coupling ◽  
Element Technique ◽  
Von Mises ◽  
Traveling Speed

Laser transmission microjoining of two dissimilar materials has become a very significant technique. In this research, a numerical method is developed using finite element technique to determine the condition of joining two dissimilar materials namely Polyethylene terepthalate (PET) and titanium. First the model is used to optimize the laser parameters like laser traveling speed and power to obtain good bonding. A good combination is achieved at the power of 8W and laser traveling speed at 150mm/min.After the verifications, the profile of residual stress of the laser microjoint has been calculated using the developed model. The residual is low near the centerline along the traveling laser beam, and a higher values is away from the centerline at the x-direction shown by the contours on the PET surface. Higher residual von Mises stress near the centerline along the traveling laser beam and the stresses reduce as the distance away from the centerline.

Effects of Deep Rolling on Surface Residual Stress and Microhardness of JIS SS400 MIG Welding

2018 ◽  
Vol 939 ◽  
pp. 31-37
Author(s):  
Adirek Baisukhan ◽  
Wasawat Nakkiew
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Welded Joint ◽  
Rolling Process ◽  
Rolling Speed ◽  
Mig Welding ◽  
Deep Rolling ◽  
Surface Microhardness ◽  
Rolling Pressure ◽  
Number Of Passes

Metal Inert Gas (MIG) welding process is a common welding process for carbon steels. During the cooling after welding, non-uniform cooling cause tensile residual stress on the surface of welded joint and, in most cases, in Heat Affected Zone (HAZ) also. The tensile residual stress is undesirable because it affects the strength and shorten the workpiece fatigue life. In order to convert the tensile residual stresses to desirable compressive residual stresses, the mechanical surface treatment like deep rolling process was used in this research. The surface residual stresses were measured by XRD machine with the sin2ψ method. For statistical analysis of significant factors used in deep rolling process, there are three factors each factor has two levels: rolling pressure, rolling speed and number of passes. Taguchi experimental design was used in conjunction with a deep rolling process to determine factors affected the surface residual stresses and surface microhardness. The results of the research showed that the most significant factors that affect the surface residual stress and surface microhardness were the number of passes, followed by the rolling pressure and the rolling speed, respectively. The maximum compressive residual stress measured at the welded joint was -521.5 MPa. The highest measured surface microhardness was 266.2 HV at the welded joint. The appropriated factors of deep rolling process for JIS SS400 MIG welding were rolling pressure 270 MPa, rolling speed 1,500 mm/min and number of passes 3 times.

scholarly journals Simultaneous X-ray radiography and diffraction topography imaging applied to silicon for defect analysis during melting and crystallization

2019 ◽  
Vol 52 (6) ◽  
pp. 1312-1320 ◽  
Author(s):  
Maike Becker ◽  
Gabrielle Regula ◽  
Guillaume Reinhart ◽  
Elodie Boller ◽  
Jean-Paul Valade ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Grain Boundaries ◽  
Growth Process ◽  
Defect Formation ◽  
Simultaneous Recording ◽  
European Synchrotron Radiation Facility ◽  
Crystal Defects ◽  
Structural Defects ◽  
X Ray

One of the key issues to be resolved to improve the performance of silicon solar cells is to reduce crystalline defect formation and propagation during the growth-process fabrication step. For this purpose, the generation of structural defects such as grain boundaries and dislocations in silicon must be understood and characterized. Here, in situ X-ray diffraction imaging, historically named topography, is combined with radiography imaging to analyse the development of crystal defects before, during and after crystallization. Two individual indirect detector systems are implemented to record simultaneously the crystal structure (topographs) and the solid–liquid morphology evolution (radiographs) at high temperature. This allows for a complete synchronization of the images and for an increased image acquisition rate compared with previous studies that used X-ray sensitive films to record the topographs. The experiments are performed with X-ray synchrotron radiation at beamline ID19 at the European Synchrotron Radiation Facility. In situ observations of the heating, melting, solidification and holding stages of silicon samples are presented, to demonstrate that with the upgraded setup detailed investigations of time-dependent phenomena are now possible. The motion of dislocations is recorded throughout the experiment, so that their interaction with grain boundaries and their multiplication through the activation of Frank–Read sources can be observed. Moreover, the capability to record with two camera-based detectors allows for the study of the relationship between strain distribution, twinning and nucleation events. In conclusion, the simultaneous recording of topographs and radiographs has great potential for further detailed investigations of the interaction and generation of grains and defects that influence the growth process and the final crystalline structure in silicon and other crystalline materials.

Influence of Deep Rolling Process Parameters on Surface Residual Stress of AA7075-T651 Aluminum Alloy Friction Stir Welded Joint

2018 ◽  
Vol 939 ◽  
pp. 23-30 ◽  
Author(s):  
Adirek Baisukhan ◽  
Wasawat Nakkiew
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Residual Stresses ◽  
Compressive Residual Stress ◽  
Welded Joint ◽  
Rolling Process ◽  
Rolling Speed ◽  
Deep Rolling ◽  
Friction Stir ◽  
Rolling Pressure

Friction stir welding is most commonly used for joining aluminum alloy parts. After welding, residual stresses occurred in the welded joint caused by non-uniform cooling rate. Friction stir welding usually generates tensile residual stress inside the workpiece which affects the strength in addition to the fatigue life of materials. Compressive residual stress usually is beneficial and it can be introduced by mechanical surface treatment methods such as deep rolling, shot peening, laser shock peening, etc. In this research, deep rolling was used for inducing compressive residual stress on surface of friction stir welded joint. The residual stresses values were obtained from X-ray diffraction machine. Influence of three deep rolling process parameters: rolling pressure, rolling speed and rolling offset on surface residual stresses at the welded joint were investigated. Each factor had 2 levels (23 full factorial design). The statistical analysis result showed that the rolling pressure, rolling speed, rolling offset, interaction between rolling pressure and rolling speed, interaction between rolling speed and rolling offset were statistically significant factors, with the most compressive residual stress value approximately -391.6 MPa. The appropriated deep rolling process parameters on surface residual stress of AA7075-T651 aluminum alloy friction stir welded joint were 1) rolling pressure about 150 bar 2) rolling speed about 1,400 mm/min 3) rolling offset about 0.1 mm.

scholarly journals Finite Element Analysis of Residual Stress in Ti-6Al-4V Alloy Plate Induced by Deep Rolling Process under Complex Roller Path

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
J. J. Liou ◽  
T. I. El-Wardany
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Reaction Force ◽  
Rolling Process ◽  
Surface Material ◽  
Deep Rolling ◽  
Alloy Plate ◽  
Near Surface ◽  
Material Recovery ◽  
Roller Path

The kinematics of the deep rolling tool, contact stress, and induced residual stress in the near-surface material of a flat Ti-6Al-4V alloy plate are numerically investigated. The deep rolling tool is under multiaxis nonlinear motion in the process. Unlike available deep rolling simulations in the open literature, the roller motion investigated in this study includes penetrative and slightly translational motions. A three-dimensional finite element model with dynamic explicit technique is developed to simulate the instantaneous complex roller motions during the deep rolling process. The initial motion of the rollers followed by the penetration motion to apply the load and perform the deep rolling process, the load releasing, and material recovery steps is sequentially simulated. This model is able to capture the transient characteristics of the kinematics on the roller and contacts between the roller and the plate due to variations of roller motion. The predictions show that the magnitude of roller reaction force in the penetration direction starts to decrease with time when the roller motion changes to the deep rolling step and the residual stress distributions in the near-surface material after the material recovery step varies considerably along the roller path.

An Inverse Approach to the Validation of Pressure Predictions in Rough Elastohydrodynamic Contacts

2001 ◽  
Vol 124 (1) ◽  
pp. 103-108 ◽  
Author(s):  
C. J. Hooke ◽  
K. Y. Li
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Rough Surface ◽  
Experimental Technique ◽  
Von Mises Stress ◽  
Stress Distributions ◽  
Inverse Approach ◽  
Controlled Conditions ◽  
Steel Disc ◽  
Von Mises

A simple experimental technique is developed that allows the pressures and stresses predicted by EHL analyses to be checked. A soft, rough steel disc is run, under controlled conditions, against a harder, smooth counterface. The pressures generated cause the soft disc to plastically deform. Once deformation ceases the residual profile may be measured and used as input to an EHL solver. The calculated pressures are then used to determine the stress distributions as the rough surface passes through the conjunction. After allowing for the build up of residual stress the maximum von Mises’ stress should be equal to the yield strength of the disc. This provides an accurate, quantitative check on the theoretical values.

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