http://hdl.handle.net/2436/22097 Sat, 18 May 2013 14:32:04 GMT 2013-05-18T14:32:04Z http://hdl.handle.net/2436/29647 Title: Finite Element Modelling of Multipass Fusion Welding with Application to Complex Geometries Authors: Jiang, Wei; Yahiaoui, Kadda Abstract: The current paper presents recently completed work in the development of advanced multi-pass weld modelling procedures, with the ultimate objective of predicting weld residual stress distributions in thick-walled complex geometries. The modelling technique was first developed using simple three-dimensional geometries, for which experimental data was available for validation purposes. All the non-linearities associated with welding, including geometry, material, and boundary non-linearities, as well as heat source movement were taken into account. The element removal/reactivate technique was employed to simulate the deposition of filler material. Combined with a newly developed meshing technique, the model was then applied to predict residual stress distributions for a relatively thick stainless steel piping branch junction. Finally, a parametric study was conducted to assess the effects of various manufacture-related welding parameters on the final residual stress fields. The interpass temperature and cooling rate were found to be the two most sensitive parameters affecting resultant residual stresses. The residual stress profiles can be optimized relatively easily by adjusting these parameters. This research demonstrated that the developed modelling technique has potential in multi-pass welding process optimization and wide industrial applications including weld repairs.(Professional Engineering Publishing) Description: The Journal’s editorial board deemed it timely to dedicate an issue to address recent developments in the field and to highlight challenges to industry to exploit state-of-the-art modelling techniques. This paper was included in the special issue and describes the application of commercial finite element software to model the multipass fusion welding process. Mon, 01 Jan 2007 00:00:00 GMT http://hdl.handle.net/2436/29647 2007-01-01T00:00:00Z http://hdl.handle.net/2436/29646 Title: Finite Element Simulation of Multipass Welding: Full Three-Dimensional Versus Generalized Plane Strain or Axisymmetric Models Authors: Jiang, Wei; Yahiaoui, Kadda; Laoui, Tahar Abstract: A full three-dimensional (3D) thermo-mechanical finite element (FE) model has been developed to simulate the step-by-step multipass welding process. Non-linearities associated with welding, such as a moving heat source, material deposition, temperature-dependent material properties, latent heat, and large deformations, were taken into account. The model was applied to multipass butt-welded mild steel plate and girth butt-welded stainless steel pipe for validation. The simulation results were compared with independently obtained experimental data and numerical predictions from two-dimensional (2D) generalized plane strain and axisymmetric models. Good agreements between the 3D predictions and experimental data have been obtained. The computational model has the potential to be applied to multipass welded complex geometries for residual stress prediction. (Professional Engineering Publishing) Description: A three-dimensional thermo-mechanical finite element model has been developed and applied to multipass butt-welded mild steel plate and girth butt-welded stainless steel pipe. The simulation results were validated with independently obtained experimental data. The computational model has the potential to be applied to multipass welded complex geometries for residual stress prediction. Sat, 01 Jan 2005 00:00:00 GMT http://hdl.handle.net/2436/29646 2005-01-01T00:00:00Z http://hdl.handle.net/2436/29645 Title: Finite Element Prediction of Residual Stress Distributions in a Multipass Welded Piping Branch Junction Authors: Jiang, Wei; Yahiaoui, Kadda Abstract: Piping branch junctions and nozzle attachments to main pressure vessels are common engineering components used in the power, oil and gas, and shipbuilding industries amongst others. These components are usually fabricated by multipass welding. The latter process is known to induce residual stresses at the fabrication stage, which can have severe adverse effects on the in-service behavior of such critical components. It is thus desirable if the distributions of residual stresses can be predicted well in advance of welding execution. This paper presents a comprehensive study of three dimensional residual stress distributions in a stainless steel tee branch junction during a multipass welding process. A full three dimensional thermomechanical finite element model has been developed for this purpose. A newly developed meshing technique has been used to model the complex intersection areas of the welded junction with all hexahedral elements. Element removal/reactivate technique has been employed to simulate the deposition of filler material. Material, geometry, and boundary nonlinearities associated with welding were all taken into account. The analysis results are presented in the form of stress distributions circumferentially along the weld line on both run and branch pipes as well as at the run and branch cross sections. In general, this computational model is capable of predicting three dimensional through-thickness welding residual stress, which can be valuable for structural integrity assessments of complex welded geometries. (ASME) Description: The research presented extends that on stress and temperature distributions in welded oil/gas steel pipe junctions, research that has resulted in Yahiaoui being invited to present to: Ecole de Technologie Supérieure, University of Québec, Montreal, August 2006, and The Structural Technology and Materials Group of the Institute of Mechanical Engineers October 2006. Mon, 01 Jan 2007 00:00:00 GMT http://hdl.handle.net/2436/29645 2007-01-01T00:00:00Z http://hdl.handle.net/2436/29644 Title: Evaluation of Limit Load Data for Cracked Pipe Bends under Opening Bending and Comparisons with Existing Solutions Authors: Yahiaoui, Kadda; Moreton, D. N.; Moffat, D. G. Abstract: Most existing limit load solutions for cracked pipe bends under in-plane bending have been developed following the experimental work by Griffiths on bends with through-wall defects or by extrapolation of solutions developed for cracked straight pipes. No data exists for part-penetrating defects. This contribution summarises recently obtained experimental and finite element results from 13 tests on axially (at the crown) and circumferentially (at the intrados) cracked carbon steel pipe bends under opening bending loads. Comparisons with predictions by existing solutions for the cases investigated are reported. The solutions are shown to be excessively conservative and, on occasions, non-applicable to the cases for which they are intended. The presented data, together with results more recently made available in the open literature, could be used to form a working basis for revising the existing solutions. (Elsevier) Description: The paper presents experimental and finite element results from tests on cracked steel pipe bends under bending. The presented data, together with results recently made available in the literature, can be used to form a working basis for revising R6 solutions. The work reported was part of a project sponsored by British Energy, the custodian of the R6 procedure. Tue, 01 Jan 2002 00:00:00 GMT http://hdl.handle.net/2436/29644 2002-01-01T00:00:00Z