Laser Welding Process Research Paper

Heat Flux for Welding Processes: Model for Laser Weld

Suresh Akella1, Harinadh Vemanaboina1, Ramesh Kumar Buddu2

1Sreyas Institute of Engineering & Technology, Hyderabad-500068

2FRMDC Division, Institute for Plasma Research, Bhat, Gandhinagar-382428.

E-mail:[e-mail]

Abstract-An accurate and physically suitable heat flux model is required to represent the welding process. Experimentally established processes are used in literature. A well established model in heat flux representation is the double ellipsoid model of Goldak it provides non symmetry of the front and rear heat to the electrode as given by Lindgren. Though this is a good representation, it can be simplified to a conical heat model for the molten metal with a Gaussian

q =Q/t in watts =joules / second, J/s. Welding heat available at the weld bead may not be constant as initially there will be time for temperature stabilization due to losses and it is stable over a period of time and subsequently, when power is switched off from the source flux will ramp down as it gathers heat from the surroundings until it equalizes to that of the surroundings. Ramp up model of heat energy can be taken as a surface heat input. This is an approximation which can be substantiated by measurements of temperatures over the surface. Addition of filler heat can be added as an

Q= Wg*qg + Wf*qf

This distribution will give a more realistic representation [3] & [4].for Laser & Electron beam welding. In this study an evaluation of, Wg= Wf =0.5 was taken and compared with Gaussian & Frustum distributions. The finite element analysis requires the discrete values of power at each node points. For a circular surface a quadratic element distribution is shown in Figure 2.

Figure2. A heat flux model for Laser Beam Welding

The Heat transfer problem is K T = F

Here the K matrix is heat conduction matrix, T is the output temperature domain and F is the heat input vector. If the Laser heat is on surface fs and fv is the heat added through volume.

F= fs + fv. fs=∫_s^ ▒NQds gives the surface heat and the volume heat transferred is given as fv=∫_v^ ▒NQdv. N is