Research on the Residual Stresses in Cold-Formed Hat-Shaped Section

2012 ◽  
Vol 204-208 ◽  
pp. 934-938
Author(s):  
Hua Chen Liu ◽  
Feng Zhao
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Cutting Tool ◽  
Electrical Discharge Machining ◽  
Stress Measurement ◽  
Strain Gauges ◽  
Test Results ◽  
Antiseptic Treatment ◽  
Experimental Findings ◽  
Shaped Section

In the paper,the electrical discharge machining(EDM) technique was used to cut strips for cold-formed residual stress measurement of hat-shaped section.After adjusting the electrolyte ratio,designing specific the cutting tool and improving the methodof antiseptic treatment,the test results improved significantly. Electrical resistance strain gauges with EDM cutting technique were used to establish the magnitude and distribution of the residual stresses in cold-formed hat-shaped section.Based on the experimental findings, an idealized distribution pattern of the residual stress in cold-formed hat-shaped section is presented.

Development and experimental validation of the deep hole method for residual stress measurement

1996 ◽  
Vol 31 (3) ◽  
pp. 177-186 ◽  
Author(s):  
R H Leggatt ◽  
D J Smith ◽  
S D Smith ◽  
F Faure
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Ferritic Steel ◽  
Experimental Validation ◽  
Stress Measurement ◽  
Thickness Distribution ◽  
Analytical Techniques ◽  
Surface Strain ◽  
Strain Gauges ◽  
Deep Hole

The development of a deep hole method, based on earlier techniques, for measuring the through-thickness distribution of residual stresses is described. The distortion of a reference hole used in the method was interpreted using analytical techniques to determine the residual stresses present. The accuracy of the method was investigated using a 100 mm deep plastically deformed ferritic steel rectangular bar. The stresses in the bar were determined by surface strain gauges. The axial residual stresses through the depth of the bar, measured by the deep hole method, were found to be within ± 35 MPa of the stresses determined from the strain gauges in the central 80 mm of the bar.

scholarly journals Cross-Sectional Mapping of Residual Stresses by Measuring the Surface Contour After a Cut

2000 ◽  
Vol 123 (2) ◽  
pp. 162-168 ◽  
Author(s):  
M. B. Prime
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Superposition Principle ◽  
New Method ◽  
Contour Method ◽  
Stress Profile ◽  
Relaxation Methods ◽  
Cross Sectional ◽  
Residual Stress Profile

A powerful new method for residual stress measurement is presented. A part is cut in two, and the contour, or profile, of the resulting new surface is measured to determine the displacements caused by release of the residual stresses. Analytically, for example using a finite element model, the opposite of the measured contour is applied to the surface as a displacement boundary condition. By Bueckner’s superposition principle, this calculation gives the original residual stresses normal to the plane of the cut. This “contour method” is more powerful than other relaxation methods because it can determine an arbitrary cross-sectional area map of residual stress, yet more simple because the stresses can be determined directly from the data without a tedious inversion technique. The new method is verified with a numerical simulation, then experimentally validated on a steel beam with a known residual stress profile.

scholarly journals UK Research Programme on Residual Stresses: A Review of Progress

2008 ◽  
Author(s):  
S. K. Bate ◽  
P. Hurrell ◽  
J. A. Francis ◽  
M. Turski
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Experimental Testing ◽  
Research Programme ◽  
Austenitic Steels ◽  
Assessment Procedure ◽  
Engineering Structures ◽  
Modelling Techniques

A long-term UK research programme on residual stresses was launched in 2004. It involves Rolls-Royce plc and Serco Assurance, supported by UK industry and academia. The programme is aimed at progressing the understanding of weld residual stresses and the implementation of finite element simulation and residual stress measurement for assessing the integrity of engineering structures. Following on from this, the intention is then to develop improved guidance on residual stress modelling techniques and then to provide methods and analysis tools for design in order to control and minimise residual stress. The focus of the work to date has been to develop modelling guidelines which can be used by a finite element analyst to predict the residual stresses in austenitic welded components. These guidelines are now drafted and will be incorporated into the next issue of the British Energy R6 defect assessment procedure following peer review. The guidelines have been developed based on the experience that has been attained using various modelling techniques. To support this development, a series of welded mock-ups have been manufactured. The residual stresses in these welds have been measured using various techniques (diffraction and strain relaxation). These measurements are being used to validate the predicted stresses. It is only by corroborating each other that the resulting residual stresses can be confidently used for assessment. Mock-ups are also being used to develop material models for ferritic steel which undergo phase transformations, and to investigate how various weld parameters affect the magnitude and distribution of residual stress. Similarly, mock-ups have been manufactured to investigate the effect of start-stops on residual stresses. The programme is also supported by experimental testing to develop physical and mechanical properties which are required for analysis, i.e. up to melting temperature. Both conventional and miniaturised testing has been used to measure properties in ferritic and austenitic steels. A task has also been undertaken to develop a methodology for providing upper bound residual stress profiles which can be used as an initial estimate of stress for use in structural assessment.

Experimental and Analytical Leak Characterization for Axial Through-Wall Cracks in a Liquids Pipeline

2014 ◽  
Author(s):  
Mohamed R. Chebaro ◽  
Nader Yoosef-Ghodsi ◽  
David M. Norfleet ◽  
Jason H. Bergman ◽  
Aaron C. Sutton
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Internal Pressure ◽  
Crack Opening ◽  
Full Scale ◽  
Leak Rate ◽  
Propagation Mechanism ◽  
Element Analysis ◽  
Fea Model ◽  
Experimental Findings

Three pipeline sections containing defects of interest were non-destructively tested in the field, cut out and shipped to a structural laboratory to undergo full-scale testing. The common objectives of the experiments were to determine (1) the leak initiation pressure and (2) the leak rate at various specified internal pressures. While two spools (Specimens A and B) contained through-wall cracks, the third (Specimen C) had a partial through-wall crack with similar characteristics. The capacity of through-wall defects to withstand a level of internal pressure without leaking is due to the resultant local, compressive hoop residual stresses. Specimen C underwent full-scale pressure cycling to further comprehend the crack propagation mechanism in order to correlate it to field operation and analytical fatigue life predictions. To enhance the understanding of the physical crack behaviour as a function of internal pressure, a comprehensive finite element analysis (FEA) model was built using SIMULIA’s Abaqus software. The model inputs incorporated results from the above-mentioned laboratory tests, in addition to extensive radial, circumferential and axial residual stress measurements using the X-ray diffraction (XRD) technique, obtained on three pipe spools cut out from the same line. The resulting crack opening parameters from FEA were input into a closed-form fluid mechanics (FM) model, which was calibrated against a computational fluid dynamics (CFD) model, to determine the corresponding leak initiation pressures and leak rates. These outcomes were then compared to experimental findings. The FEA and FM models were subsequently employed to carry out a parametric study for plausible combinations of feature geometries, material properties, operational pressures and residual stresses to replicate field conditions. The key outcome from this study is the experimental and analytical demonstration that, for given fluid properties and pressures, the leak threshold and leak rate for through-wall cracks are primarily dependent upon the crack geometry and local residual stress distributions.

Effect of Superficial Residual Stresses on Abrasive Wear Resistance of Al2O3 / Al2O3+3Y-TZP Multilayers

2005 ◽  
Vol 502 ◽  
pp. 217-224
Author(s):  
Goffredo de Portu ◽  
L. Micele ◽  
D. Prandstraller ◽  
G. Palombarini ◽  
Giuseppe Pezzotti
Keyword(s):  
Residual Stress ◽  
Wear Resistance ◽  
Residual Stresses ◽  
Abrasive Wear ◽  
Compressive Stress ◽  
Compressive Residual Stress ◽  
Tape Casting ◽  
Cold Isostatic Pressing ◽  
Abrasive Wear Resistance ◽  
Test Results

Multilayered composite specimens consisting of Al2O3 / Al2O3+ 3Y-TZP (A/AZ) layers with different compositions and thicknesses were prepared starting from ceramic sheets obtained by tape casting. Residual stresses arisen from mismatch in thermal expansion coefficient during sintering were evaluated using luminescence piezo-spectroscopy. The stress in the superficial A layer was found to be compressive, and its value depended on the ratio between thickness of A and AZ layer. The influence of the superficial compressive stress on the abrasive wear resistance was investigated using microscale ball cratering test; results were correlated with the superficial compressive stress and compared with a specimen of pure unstressed Al2O3 prepared both by lamination and by cold isostatic pressing. Experiments show an improvement of performances in the samples containing compressive residual stress in the surface.

UK Research Programme on Residual Stresses: Progress to Date

2007 ◽  
Author(s):  
S. K. Bate ◽  
A. P. Warren ◽  
C. T. Watson ◽  
P. Hurrell ◽  
J. A. Francis
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Research Programme ◽  
Assessment Procedure ◽  
Engineering Structures ◽  
Element Analysis ◽  
Simplifying Assumptions ◽  
Modelling Techniques

A long-term UK research programme on residual stresses was launched in 2004. It involves Rolls-Royce plc and Serco Assurance, and is supported by UK industry and academia. The programme is aimed at progressing the understanding of weld residual stresses and the implementation of finite element simulation and residual stress measurement for assessing the integrity of engineering structures. Following on from this, the intention is then to develop improved guidance on residual stress modelling techniques. In the first two years finite element activities have addressed heat source representation, simplified modelling (e.g. 2D v 3D, bead lumping), material hardening models, high temperature behaviour and phase transformations. It is recognized that simplifying assumptions have to be made in order to reduce the computational run-time and modelling complexity, especially for multi-pass welds. The effects of these assumptions on the determined stresses have been considered by carrying out finite element analyses of welded mock-ups. The welded mock-ups have been developed to provide measured residual stress data which are necessary to validate the modelling techniques that have been developed. These activities have been used to support the development of guidelines on the use finite element analysis to predict residual stresses in welded components. These guidelines will be incorporated in the next issue of the British Energy R6 defect assessment procedure.

Evaluation of Welding Residual Stresses in Power Plant Facilities by Using a Newly Developed Indentation Technique

2002 ◽  
Author(s):  
Jae-il Jang ◽  
Dongil Son ◽  
Yeol Choi ◽  
Yun-Hee Lee ◽  
Won-Jae Ji ◽  
...  
Keyword(s):  
Residual Stress ◽  
Power Plant ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Welding Residual Stress ◽  
Large Scatter ◽  
Indentation Technique ◽  
Cutting Test ◽  
Non Destructive ◽  
Non Destructive Techniques

It is well known that residual stress is one of the important problems in welding design/fabrications and sound maintenance of welded structures. Thus, the demand for quantitative evaluation of welding residual stress has been increased. However, conventional non-destructive techniques for welding residual stress measurement have many difficulties in in-field applications according to poor repeatability, large scatter of obtained data, complex procedures, inaccurate results, and etc. To overcome these difficulties, a newly developed indentation technique was proposed in this study, and applied to evaluate the welding residual stress in electric power plant facilities. By comparing with the stress values obtained from the destructive saw-cutting test, it could be concluded that the new indentation technique is very useful for quantitative/non-destructive evaluation of welding residual stresses in industrial fields such as power plant facilities.

Experimental characterization and finite element modeling of the residual stresses in laser-assisted mechanical micromachining of Inconel 625

2015 ◽  
Vol 231 (10) ◽  
pp. 1735-1751 ◽  
Author(s):  
Avik Samanta ◽  
Mahesh Teli ◽  
Ramesh Singh
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Cutting Forces ◽  
Laser Heating ◽  
Stress Measurement ◽  
Cutting Speed ◽  
Inconel 625 ◽  
Beam Diameter ◽  
Mechanical Micromachining

Laser-assisted mechanical micromachining offers the ability to machine difficult-to-cut materials, like superalloys and ceramics, more efficiently and economically by laser-induced localized thermal softening prior to cutting. Laser-assisted mechanical micromachining is a micromachining process with localized laser heating which could affect the cutting forces and the machined surface integrity. The residual stresses obtained in the laser-assisted mechanical micromachining process depend on both mechanical loading and the laser heating. This article focuses on the experimental process characterization and prediction of the cutting forces and the residual stresses in a laser-assisted mechanical micromachining–based orthogonal machining of Inconel 625. The results show that the laser assistance reduces the mean cutting forces by ∼25% and enhances the normal compressive residual stress at the surface by ∼50%. Since microscale residual stress measurement is very time-intensive, a coupled-field thermo-mechanical finite element model of laser-assisted mechanical micromachining has been developed to predict the temperature, cutting forces and the residual stresses. The cutting forces and residual stresses’ predictions are in good agreement with the measured values during machining. In addition, parametric simulations have been carried out for laser power, cutting speed, cutting edge radius, rake angle, laser location and laser beam diameter to study their effect on cutting forces and surface residual stresses.

Wheel Rim Axial Residual Stress and a Proposed Mechanism for Vertical Split Rim Formation

2011 ◽  
Author(s):  
Cameron Lonsdale ◽  
John Oliver
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Axial Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Axial Residual Stress ◽  
Railroad Wheels ◽  
Hoop Stresses ◽  
Future Work

Railroad wheels are manufactured with beneficial residual compressive hoop stresses, which are imparted by rim quenching and tempering. Hoop and radial residual stresses for wheels have been studied in detail by various organizations over the years and are relatively well characterized. However axial residual stresses, in the orientation across the rim width from back rim face to front rim face, have not been extensively investigated. This paper describes a failure mode known as a vertical split rim (VSR) and describes efforts to measure the axial residual stresses in, 1) new wheels, 2) service worn wheels and 3) wheels that have failed from VSRs. Initial axial residual stress measurement efforts, using core drilling and x-ray diffraction from the tread surface, are briefly reviewed. Further more extensive work using x-ray diffraction to measure axial residual stress on radial wheel slices is described and data are presented, focusing on differences between the three wheel types. The concept of Axial Stress Amplification (ASA) is outlined, and the relationship of axial residual stress to VSRs is discussed. A proposed mechanism for VSR formation is described. Future work, with a goal of reducing or eliminating VSRs in service, is considered.

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