Numerical simulation of the laser welding process in butt-joint specimens

Effects of welding speed, energy input and heat source distribution on temperature variations in butt joint welding

The main emphasis of this review is on thermal modelling and prediction of laser welding in metals. However as similar techniques are employed to model conventional welding processes such as arc, resistance and friction, as well as related processes such as alloying, cladding and surface hardening, part of this review is given over to the modelling of these processes where appropriate. The time frame of the review is up to the year 2002.

Thermal modelling of laser welding and related processes: a literature review

The analytical solution for a double-ellipsoidal power density moving heat source in a semi-infinite body with conduction-only consideration has been derived. The solution has been obtained by integrating the instant point heat source throughout the volume of the ellipsoidal one. Very good agreement between the predicted transient temperatures and the measured ones at various points in bead-on-plate specimens has been obtained. The predicted geometry of the weld pool is also in good agreement with the measured one. This may pave the way for the future applications of this solution in the problems such as microstructure modeling, thermal stress analysis, residual stress/distortions and welding process simulation.

Analytical solutions for transient temperature of semi-infinite body subjected to 3-D moving heat sources

Prediction of welding distortion in butt joint of thin plates.

Finite-element prediction of distortion during gas metal arc welding using the shrinkage volume approach

A finite element fluid dynamics model that incorporates nonlinear temperature and compositionally dependant material properties has been used to study the flow patterns generated by the interaction of molten metal droplets with a weld pool surface. The effects of single and successive droplet transfer, droplet composition, temperature, velocity, size and transfer rate have been investigated. The model shows droplet transfer strongly influences the flow pattern within the weld pool. At low transfer rates, typical of low welding current (100 A), the relative surface tensions of the pool and the droplet influence the fluid flow within the weld pool, whereas at higher transfer rates, typical of medium current (200 A), the flow is dominated by the momentum of the impacting droplet. Experimental determination of weld pool geometries for bead-on-plate welds, at different current levels, on plates selectively doped with sulfur, have provided some support for the model predictions. This work demonstrates that droplet-induced convective flow should be included when modeling the weld pool behavior in GMAW.

An investigation of the interaction of a molten droplet with a liquid weld pool surface : A computational and experimental approach

The gas metal arc welding process (a method of joining two metals by diffusion) is used to join metal in many industrial applications. Restraining forces arise from the nonuniform thermal field generated by welding. In this study, restraining force exerted during the welding process is calculated both numerically and experimentally. In numerical analysis, finite element software (ANSYS) has been used. In experimental analysis, a jig was designed and built that uses load cells to measure the force required to restrain two mild steel plates (base plate) while they are being welded by an automatically controlled welding robot. After checking for reliability, tests were carried out to determine the effects of various welding speeds and heat inputs on the restraining forces. The results showed that welding speed has little effect on the restraining force but by increasing heat input, restraining forces increase significantly. The most relevant and useful information on the effects of the welding conditions is derived from the slope of the graph of the force vs. the distance traveled in time. The finite element predictions of restraining force due to various welding conditions produce similar trends and the slopes as the experimental results.

M. J. Painter

Papers

Finite-element prediction of distortion during gas metal arc welding using the shrinkage volume approach

An investigation of the interaction of a molten droplet with a liquid weld pool surface : A computational and experimental approach

Experimental and numerical simulation of restraining forces in gas metal arc welded joints

A literature review on numerical modelling of the gas metal arc welding process