Measurement of residual stresses in beams and plates using the crack compliance technique

2000 ◽  
Vol 35 (4) ◽  
pp. 277-285 ◽  
Author(s):  
D Nowell ◽  
S Tochilin ◽  
D. A Hills
Keyword(s):  
Experimental Data ◽  
Residual Stress ◽  
Dislocation Density ◽  
Neutron Diffraction ◽  
Finite Thickness ◽  
Beam Theory ◽  
Kernel Functions ◽  
Surface Strain ◽  
Stress Fields ◽  
Strain Gauges

The crack compliance method provides a useful extension to the range of techniques available for the measurement of residual stress fields. The method is most suitable for simple geometries where the stresses vary in one direction only (e.g. usually depth). This paper describes the application of the dislocation density method to the calculation of the compliance functions required for the analysis of experimental data (the surface strain changes as a slot is cut). In particular, the kernel functions appropriate to a specimen of finite thickness (i.e. a beam or a plate) are given. The use of the technique for this geometry, including the use of multiple strain gauges, is discussed. Some sample results are given for the case of a plastically bent beam and these are compared with predictions from beam theory and with neutron diffraction measurements.

Design Optimisation of a Ferritic Ring Weld Specimen Using FE Modelling

2009 ◽  
Author(s):  
Christopher M. Gill ◽  
Paul Hurrell ◽  
John Francis ◽  
Mark Turski
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Stress Field ◽  
Finite Element Modelling ◽  
Post Weld Heat Treatment ◽  
Stress Fields ◽  
Element Modelling ◽  
Weld Heat

This paper describes the design optimisation of an SA508 ferritic steel ring weld specimen using FE modelling techniques. The aim was to experimentally and analytically study the effect of post weld heat treatment upon a triaxial residual stress field. Welding highly constrained geometries, such as those found in some pressure vessel joints, can lead to the formation of highly triaxial stress fields. It is thought that application of post weld heat treatments will not fully relax hydrostatic stress fields. Therefore a ferritic multi-pass ring weld specimen was designed and optimised, using 2D finite element modelling, to generate a high magnitude triaxial stress field. The specimen thickness and weld-prep geometry was optimised to produce a large hydrostatic stress field and still allow efficient use of neutron diffraction to measure the residual stress. This paper reports the development of the test specimen geometry and compares the results of welding FE analysis and neutron diffraction measurements. Welding residual stresses were experimentally determined using neutron diffraction; both before post weld heat treatment. Three dimensional moving heat source weld finite element modelling has been used to predict the residual stresses generated by the welding process used. Finite element modelling examined the effect of phase transformation upon the residual stress field produced by welding. The relaxation of welding stresses by creep during post weld heat treatment has also been modelled. Comparisons between the modelled and measured as-welded residual stress profiles are presented. This work allows discussion of the effect of post weld heat treatment of triaxial stress fields and determines if finite element modelling is capable of correctly predicting the stress relaxation.

ENPOWER: Investigations by Neutron Diffraction and Finite Element Analyses on Residual Stress Formation in Repair Welds Applied to Ferritic Steel Plates

2005 ◽  
Author(s):  
Carsten Ohms ◽  
Robert C. Wimpory ◽  
Dimitar Neov ◽  
Didier Lawrjaniec ◽  
Anastasius G. Youtsos
Keyword(s):  
Experimental Data ◽  
Residual Stress ◽  
Numerical Analysis ◽  
Neutron Diffraction ◽  
Stress Field ◽  
Ferritic Steel ◽  
Maximum Stress ◽  
Steel Plates ◽  
Residual Stress Field ◽  
Welding Procedure

The European collaborative research project ENPOWER (Management of Nuclear Plant Operation by Optimizing Weld Repairs) has as one of its main objectives the development of guidelines for the application of repair welds to safety critical components in nuclear power plants. In this context letter box repair welds applied to thin ferritic steel plates to simulate repair of postulated shallow cracks have been manufactured for the purpose of experimental and numerical analysis of welding residual stresses. Two specimens have been procured, one of them prepared in accordance with a standard welding procedure, while in the second case a different procedure was followed in order to obtain extended martensite formation in the heat affected zone. Residual stresses have been determined in both specimens by neutron diffraction at the High Flux Reactor of the Joint Research Centre in Petten, The Netherlands. In parallel Institut de Soudure in France has performed a full 3-d analysis of the residual stress field for the standard welding case taking into account the materials and phase transformations. The experimental data obtained for both specimens clearly suggest that the non-conventional welding procedure rendered higher maximum stress values. In the case of the standard welding procedure numerical and experimental data show a reasonable qualitative agreement. The maximum stress value was in both cases found in the same region of the material — in the base metal just underneath the weld pool — and in both cases found to be of similar magnitude (∼800 MPa found in neutron diffraction and ∼700 MPa found in numerical analysis). In this paper the experimental and numerical approaches are outlined and the obtained results are presented. In addition an outlook is given to future work to be performed on this part of the ENPOWER project. A main issue pending is the application of an optimized advanced post weld heat treatment in one of the two cases and the subsequent numerical and experimental determination of its impact on the residual stress field. At the same time further evaluation of the materials transformations due to welding is pursued.

Engineering Applications of Synchrotron X-Rays and Neutrons and the FaME38 Project

2004 ◽  
Author(s):  
P. J. Webster ◽  
Z. Chen ◽  
D. J. Hughes ◽  
A. Steuwer ◽  
B. Malard ◽  
...  
Keyword(s):  
Residual Stress ◽  
Surface Strain ◽  
Stress Fields ◽  
Diagnostic Tools ◽  
X Rays ◽  
X Ray ◽  
Engineering Research ◽  
Materials Engineering ◽  
Set Up ◽  
Non Destructive

Large Central Scientific Facilities such as the ESRF (the European Synchrotron Radiation Facility) and ILL (the European centre for neutron research), were set up to provide scientists with the advanced facilities they need to exploit neutron and synchrotron X-ray beams for scientific research. Engineers also conduct research at these Facilities, but this is less common as most practicing engineers generally have little or no knowledge of neutron or X-ray scattering, or of their considerable potential for engineering research, model validation, material development and for fatigue and failure analysis. FaME38 is the new joint support Facility for Materials Engineering, located at ILL-ESRF, set up to encourage and to facilitate engineering research by engineers at these facilities. It provides a technical and knowledge centre, a materials support laboratory, and the additional equipment and resources that academic and industrial engineers need for materials engineering research to become practicable, efficient and routine. It enables engineers to add the most advanced scientific diffraction and imaging facilities to their portfolio of diagnostic tools. These include non-destructive internal and through-surface strain scanning, phase analysis, radiography and tomography of engineering components. Synchrotron X-ray and neutron diffraction strain mapping is particularly suited for the rigorous experimental, non-destructive, validation of Finite Element and other computer model codes used to predict residual stress fields that are critical to the performance and lifetimes of engineering components. This paper discusses the FaME38 facility and demonstrates its utility in gaining fundamental insight into mechanical engineering problems through examples, including studies of railway rails, welds and peened surfaces that demonstrate the potential of neutron of synchrotron X-ray strain scanning for the determination of residual stress fields in a variety of engineering materials and critical components.

scholarly journals Residual Stress Evaluation of Carburized Transmission Steel Gear Using Neutron and Synchrotron X-Ray Diffraction and Finite Element Methods

2010 ◽  
Vol 652 ◽  
pp. 31-36 ◽  
Author(s):  
Yoshihisa Sakaida ◽  
Takanori Serizawa ◽  
M. Kawauchi ◽  
M. Manzanka
Keyword(s):  
Finite Element Method ◽  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Carbon Content ◽  
Residual Strain ◽  
Stress Fields ◽  
X Ray ◽  
Residual Strains ◽  
Transmission Gear

A motorcycle transmission gear of chromium-molybdenum steel with 0.2%C was carburized in carrier gas. Carburizing process including heating, carburizing, diffusing and quenching was simulated using elastoplastic finite element method. The carbon content, hardness, residual strain and residual stress fields of gear were analyzed. The unstressed lattice plane spacing and residual strains of the interior near the internal spline of gear were experimentally measured by synchrotron x-ray and neutron diffraction methods. As a result, the analyzed carbon content and hardness gradients of gear accorded with the experimental results. The radial, hoop and axial directions of cylindrical gear were found to be not always principal axes of residual stress field. On the other hand, the analyzed residual strains in the radial, hoop and axial directions of gear slightly discorded with the experimental results. Although correlation between the measured three strains was similar to that of the weighted average of analyzed strains, residual strain and stress fields of motorcycle transmission gear could not be accurately predicted at the present finite element analysis. It was concluded that carbon diffusion phenomenon and resultant hardening could be analyzed by the finite element method, and the actual interior residual strain and stress fields should be nondestructively measured by neutron diffraction method.

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.

Neutron diffraction methods for the study of residual stress fields

1985 ◽  
Vol 34 (4) ◽  
pp. 445-473 ◽  
Author(s):  
A.J. Allen ◽  
M.T. Hutchings ◽  
C.G. Windsor ◽  
C. Andreani
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Stress Fields
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