Numerical modelling of residual stress redistribution induced by TIG-dressing: TIG-dressing numerical modelling

TIG-dressing is a technique used to improve the fatigue strength of welded joints by a remelting of the weld toe region that promotes both a smoother transition between the plate and the weld crown and a residual stress redistribution. These effects are very hard to be quantified by numerical simulation since a highly coupled thermo-fluid-mechanical analysis is required. However, if the final weld toe geometry is supposed to be known or a-posteriori measured, a simplified numerical method can be used to simulate the residual tress redistribution that uses the activation-deactivation function of elements. This technique is applied to a real steel weldment and results, in terms of phases proportions and residual stress redistribution, were found in good agreement both with data coming from metallurgical analysis and the improved fatigue strength observed on welded joints after the TIG-dressing operation

Asymptotic residual stress distribution induced by multipass welding processes

publisher: Elsevier articletitle: Asymptotic residual stress distribution induced by multipass welding processes journaltitle: International Journal of Fatigue articlelink: http://dx.doi.org/10.1016/j.ijfatigue.2016.11.022 content_type: article copyright: © 2016 Elsevier Ltd. All rights reserved

A simplified model for TIG-dressing numerical simulation

journal_title: Modelling and Simulation in Materials Science and Engineering article_type: paper article_title: A simplified model for TIG-dressing numerical simulation copyright_information: © 2017 IOP Publishing Ltd date_received: 2016-12-01 date_accepted: 2017-02-22 date_epub: 2017-03-1

Three-dimensional modelling of coupled flow dynamics, heat transfer and residual stress generation in arc welding processes using the mesh-free SPH method

In this paper, a novel mesh-free approach is applied for modelling thermo-mechanical responses in a three-dimensional arc welding configuration using the Smoothed Particle Hydrodynamics (SPH) method. A fully coupled three-dimensional elastoplastic and heat transfer analysis is used to study the flow pattern of the filler material, and the resulting plastic strain development and temperature distributions for a simple arc welding configuration. The mesh-less and Lagrangian nature of SPH enables modelling of problems with large deformation and discontinuities, avoiding several disadvantages of the traditional mesh-based methods (e.g., FEM, FDM and FVM), and it is also able to implement coupled physics and complex constitutive behaviours due to the history tracking ability of the method. The plastic deformation and temperature distribution of the metal in the weld pool and the surrounding parent material are analysed during the cooling stage using SPH, and the resulting residual stresses are evaluated. This work establishes the capability of SPH as a three-dimensional modelling tool for gaining insights into the key physical processes of material deposition and its subsequent evolution during welding processes. Arc welding generates a non-uniform plastic strain distribution. The welding speed is found to be a crucial factor in controlling the plastic strain distribution and the quality of the welded joint, and there is a critical welding speed which produces the most uniform plastic strain distribution in the weld pool. The SPH method is able to predict the long term thermo-mechanical responses, namely heat transfer and residual stresses in the welded joint during the cooling stage. The SPH solutions demonstrate non-uniform cooling rates and temperature fields in a workpiece, as exhibited in practical welding processes. The solutions also show the existence of high temperature gradients around the boundary of the weld, which causes rapid microstruc