Numerical simulation of the dynamic characteristics of weld pool geometry with step-changes of welding parameters

Abstract

The gas tungsten arc welding process is an uncertain nonlinear multivariable system. In order to control the welding process, the nonlinear dynamic relationship between the weld pool geometry reflecting the weld quality and the welding parameters must be developed. A three-dimensional numerical model is developed to investigate the dynamic characteristics of the weld pool geometry when the welding current and welding speed undergo a step-change. Under the welding conditions employed in this research, the transformation periods are about 4 s for a 20 A down step-change of welding current, and about 2 s for a 20 mm min −1 up step-change of welding speed, respectively. At the initial stage during the step-change of welding current and welding speed, the responses of weld pool geometry are quicker, but they slow down subsequently until the weld pool reaches a new quasi-steady state. Welding experiments were conducted to verify the simulation results. It was found that the predicted weld pool geometries agree with the measured ones.

Determination and Application of Double Ellipsoid Heat Source Model Parameters

“…Some researchers have established corresponding models for the two-dimensional transient or 3d quasi-steady state problems of fixed arc [1,2]. And most of them are in planar heat source mode, and more and more researchers are paying attention to the 3d transient behavior of welding pool and have achieved good results [3].…”

“…Some researchers have established corresponding models for the two-dimensional transient or 3d quasi-steady state problems of fixed arc [1,2]. And most of them are in planar heat source mode, and more and more researchers are paying attention to the 3d transient behavior of welding pool and have achieved good results [3].Is proposed in this paper the double ellipsoid heat source model can well reflect the power density distribution of GTAW welding arc, because there is no clear formula to determine the double ellipsoid body heat source distribution parameter value, how to choose, need a lot of trial process to get reasonable distribution of heat source parameter value. This paper analyzes reasons for this, gives the application of SYSWELD software calibration tool to determine the double ellipsoid body heat source distribution parameter of the method; Using correction moving double ellipsoid heat source model, under the action of the arc movement of GTAW welding 3 mm thick stainless steel sheet welding process has carried on the finite element simulation, predict the three-dimensional transient when plate welding molten pool in the shape of dynamic evolution, and test verification.…”

Three-dimensional vision applications in GTAW process modeling and control

“…A three-dimensional finite element model was developed to analyze transient heat flow and predict the formation of the weld pool, and the correlation among the parameters including [18]. After the action of arc pressure, surface tension, gravity, fluid dynamics, and shear stress from the plasma were analyzed; a 3D numerical model was developed to investigate the dynamic characteristic of the weld pool geometry; and the predicted weld pool geometry was verified [19].…”

Um programa de computador para simular alguns aspectos operacionais da soldagem MIG/MAG

“…Estas técnicas foram usadas para estudar fenômenos no arco e na poça de fusão [8][9][10][11][12][13][14] e a dissipação de calor na peça [15][16].…”