The European Network on Neutron Techniques Standardization for Structural Integrity (NeT)

Ohms, Carsten; Martins, R.V.; Uca, O.; Youtsos, A.G.; Bouchard, P. J.; Smith, Marcus; Keavey, Mike; Bate, S. K.; Gilles, Philippe; Wimpory, Robert C.; Edwards, L.

doi:10.1115/pvp2008-61913

Cited by 8 publications

(10 citation statements)

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“…The example considered here is a benchmark proposed by Task Group 4 of the European Network on Neutron Techniques Standardization for Structural Integrity (NeT). The general aim of the NeT is to develop experimental and numerical techniques, and standards for the reliable characterization of residual stresses in welded structures [28]. Task Group 4 deals with the estimation of residual stress fields in a 3-pass slot weld obtained with the tungsten-inert-gas (TIG) process, in an 18 mm thick plate made of AISI 316L austenitic stainless steel [29].…”

Section: Benchmark Modelmentioning

confidence: 99%

A New Nodal-Integration-Based Finite Element Method for the Numerical Simulation of Welding Processes

Jia

Bergheau

Leblond

et al. 2020

Metals

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This paper aims at introducing a new nodal-integration-based finite element method for the numerical calculation of residual stresses induced by welding processes. The main advantage of the proposed method is to be based on first-order tetrahedral meshes, thus greatly facilitating the meshing of complex geometries using currently available meshing tools. In addition, the formulation of the problem avoids any locking phenomena arising from the plastic incompressibility associated with von Mises plasticity and currently encountered with standard 4-node tetrahedral elements. The numerical results generated by the nodal approach are compared to those obtained with more classical simulations using finite elements based on mixed displacement–pressure formulations: 8-node Q1P0 hexahedra (linear displacement, constant pressure) and 4-node P1P1 tetrahedra (linear displacement, linear pressure). The comparisons evidence the efficiency of the nodal approach for the simulation of complex thermal–elastic–plastic problems.

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Section: Benchmark Modelmentioning

confidence: 99%

A New Nodal-Integration-Based Finite Element Method for the Numerical Simulation of Welding Processes

Jia

Bergheau

Leblond

et al. 2020

Metals

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“…Reference is made to [11] and to previous publications [12,13] for a description of strain and stress measurements by means of neutron and X-ray diffraction. The neutron diffraction measurements were carried out at room temperature utilizing the E3 diffractometer, installed at the BER II reactor [14].…”

Section: Samples Characterization and Experimental Techniquementioning

confidence: 99%

“…The latter also depend on the basic material properties and on the welding process. Therefore it is clear that bulk characterization of nuclear welds is much more complicated than it is for base materials and that neutron diffraction is indispensable for such investigations [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Stress Distributions in P91 Martensitic Steel and in AISI 316LN Steel Welds for Gen IV Nuclear Applications

Agostini

Barbieri

Coppola

et al. 2020

J. Synch. Investig.

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Neutron diffraction has been utilized to investigate the stress field in two different welds developed for nuclear applications, namely: a Tungsten Inert Gas (TIG) weld of P91 martensitic steel (Cr 9 Mn 6 Mo 1 C 0.1 Fe bal wt%) and a hybrid laser beam and gas metal arc weld (LB-GMAW) of AISI316LN austenitic steel (17.8 Cr, 12.3 Ni, 1.7 Mn, 2.4 Mo, 0.3 Si Fe bal wt%). The sizes of the investigated welded samples were 100 x 50 x 12 mm 3 for the P91 weld and 220 x 160 x 15 mm 3 for the 316LN weld; unstrained references were prepared for both welds. The neutron diffraction measurements have been carried out utilizing the E3 diffractometer at the BER II reactor in Berlin, with a gauge volume of 2x2x2 mm 3 ; lines perpendicular to the weld direction were scanned at different depths inside the material and at different distances from the weld center, including the heat affected zone (HAZ) and the weld center. Strain and stress values were determined in the three principal directions. In the TIG P91 weld the stresses are almost completely relieved after a post-weld heat treatment (PWHT) of 2 h at 760°C. In the LB-GMAW 316LN weld, not submitted to PWHT, nearly balancing longitudinal and transverse stress components as high as 300-350 MPa are found within a range of approximately 3 mm around the center of weld.

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“…Some 35 academic and industrial organisations active in structural integrity–related research on materials and processes participate in NeT. The network undertook to apply advanced experimental and numerical techniques to assess phenomena, such as residual stresses and thermal ageing effects, in materials and components relevant to their structural integrity [10]. Several benchmark studies were carried out by NeT.…”

Section: Introductionmentioning

confidence: 99%

Simulation and Validation of Welding Residual Stresses Based on Non‐Linear Mixed Hardening Model

Xu¹,

Gilles²,

Duan³

2012

Strain

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This study contributes to Phase 2 of the Task Group 1 round robin in the NeT European Network. To obtain better prediction results, in the thermal analysis, two significant changes are used. The welding efficiency, η, is fixed at 75%, and the weld bead fusion boundary profiles are based upon macrographs taken from welded specimens, which have been destructively examined. In the subsequent mechanical simulation, a non‐linear kinematic or mixed isotropic–kinematic hardening model should be employed, and a progressive annealing scheme or explicit consideration of visco‐plastic or creep effects should be implemented to handle high‐temperature inelastic strains and reduce stress discontinuities. In this study, an uncoupled 3D thermal and mechanical analysis was carried out using the software code SYSWELD. In the thermal simulation, a two‐offset‐double‐ellipsoid heat source model was developed, and the parameters were fitted using the heat source fitting tool. Power intensity was applied to simulate 1‐s dwelling time at the weld start end. Offset distances between two double ellipsoids were adjusted to obtain the weld bead transverse fusion boundary profiles at different positions. Predicted temperatures were compared with the measured data by thermocouples on the test pieces. In the mechanical analysis, a new material constitutive model, non‐linear mixed hardening model, was developed. Tension–compression cyclic tests were simulated at different temperatures using three different material hardening models (isotropic hardening model, kinematic hardening model and non‐linear mixed isotropic–kinematic hardening model), and the predicted cyclic stress–strain curves were compared with the measured data. Effects of three different hardening models on the welding residual stresses were studied. Compared with the measured data, the optimum material hardening model was confirmed.

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The European Network on Neutron Techniques Standardization for Structural Integrity (NeT)

Cited by 8 publications

References 0 publications

A New Nodal-Integration-Based Finite Element Method for the Numerical Simulation of Welding Processes

A New Nodal-Integration-Based Finite Element Method for the Numerical Simulation of Welding Processes

Stress Distributions in P91 Martensitic Steel and in AISI 316LN Steel Welds for Gen IV Nuclear Applications

Simulation and Validation of Welding Residual Stresses Based on Non‐Linear Mixed Hardening Model

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