Tuesday, 12 October 2004 - 2:15 PM

This presentation is part of : Advanced modeling for laser-material processing

Numerical Modeling of Metal Heating Using Ultra-Short Pulsed Lasers

Benxin Wu, Department of Mechanical Engineering, Purdue University, West Lafayette, IN 47907 and Hai-Lung Tsai, Department of Mechanical and Aerospace Engineering and Engineering Mechanics, University of Missouri-Rolla, Rolla, MO 65409.

This work is concerned with the comparative study on parabolic one-step (POS), parabolic two-step (PTS) and hyperbolic two-step (HTS) heat conduction models in two-dimensional numerical modeling of ultra-short pulse laser metal heating. Finite difference method is applied in numerical modeling. Four different cases are investigated and simulated. It is demonstrated that, when the pulse duration is 1 micro-second, no difference is observed between the simulation results from parabolic one-step model and the results from parabolic two-step model; when the duration is 1 ns, although the difference is observable, POS model is still a good approximation of PTS model; when the duration is 1 ps, non-equilibrium heating effect becomes important, and the two-step models must be employed to get accurate results. But the hyperbolic effect is not very obvious, and PTS model is still a good approximation of hyperbolic two-step model. When the pulse duration is 0.1 ps, the hyperbolic effect is more obvious, and the difference between the results from HTS model and PTS model becomes larger. The mechanisms behind these are analyzed. A novel figure of merit (FOM) used in the evaluation of mirror coating materials is put forward based on two-step models.

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