Estimation of Heat Source Model’s Parameters for GMAW with Non-linear Global Optimization—Part I: Application of Multi-island Genetic Algorithm

Abstract

<jats:p>Estimating the thermo-elasto-plastic deformation by arc welding through finite element analysis has been used in various industrial fields. The Goldak heat source model is one of the most important and widely used models in finite element analysis, and its parameters are estimated based on the results of previous studies and tests. Part I of this study focused on the adequate heat source model, and the study for the welding deformation with the moving heat source will be done on the latter research. This study used the parameters of Goldak’s heat source model, weld efficiency, and the location of the heat source as design variables, and defined the Heat Affected Zone (HAZ) boundary line of Bead on Plate (BOP) welding as the target. BOP welding was performed using SS400 plates, the HAZ boundary line was determined based on examining the shape of the cross-section, and the optimization condition was that temperature inside the boundary line exceeded 727 °C while the temperature outside the line did not exceed 727 °C during the welding process. During this process, a multi-island genetic algorithm (non-linear global optimization method) was used to obtain the optimal results out of 1000 candidate groups, in which the HAZ boundary was similar to the experimental results. Applying a global optimization algorithm to determine the parameters of the most important heat source model to analyze welding deformation is significant, and this may be applied in various industrial fields that use welding including shipbuilding, aviation, and machinery industries.</jats:p>

Numerical evaluation of temperature fields and residual stresses in butt weld joints and comparison with experimental measurements

“…As shown in this figure, the geometry and shape of both weld seam and HAZ are well numerically replicated. As matter of the fact, the HAZ can be defined as the section reaching a temperature higher than 727°C during the welding process 58 …”

“…As matter of the fact, the HAZ can be defined as the section reaching a temperature higher than 727 C during the welding process. 58 By comparing the numerical results with the experimental ones, it is possible to state that the used methodology is suitable to predict very accurately the temperatures distribution in the welded joint, without the need to perform a tuning process to opportunely calibrate the heat source. 17,27,32,35,36,46…”

Dissimilar Non-Ferrous Metal Welding: An Insight on Experimental and Numerical Analysis

“…The time taken to perform analysis can be default or modified by the operator, based on the mesh size and refinement of the design. Semi-ellipsoidal and Double-ellipsoidal heat source models were proposed by Goldak et al, 1984 [31] as well as rectangular heat sources [32] which are used in most current FEM models [33] (Figure 4). The type of FEM selected determines the accuracy and time consumption of the analysis (Figure 5).…”

“…However, before selecting FEM software for numerical simulations, researchers should have some knowledge of the types of hardening models (Table 1), heat source models [33,[38][39][40] (Table 2), and element types [41,42] (Table 3) available in the software. As previously mentioned, plastic deformation should be simulated on hexahedral elements rather than on linear or quadratic tetrahedral elements [27].…”

A Study to Derive Equivalent Mechanical Properties of Porous Materials with Orthotropic Elasticity

“…In this study, Abaqus 2020 by Dassault Systèmes was used as a finite element method program. Abaqus has been widely used in academia and industry due to its technical feasibility [ 18 , 19 ]. Using the result file derived from the finite element method program, the elastic modulus matrix was derived, and Python (Version 3.8.5, Python Software Foundation Beaverton, OR, USA) was applied to derive the equivalent properties of a material with pores from the elastic modulus matrix.…”