Finite element model for femtosecond laser pulse heating using dual phase lag effect

The ultrashort pulse laser in material processing of micro/nanoscale has emerged as a useful application due to its capability of high precision control on heating and heat affected zone. The non-Fourier effect in heat conduction becomes more predominant as the duration of heating becomes extremely small which is the case of ultrashort pulse laser. To analyze the heat transfer process by an ultrashort pulse laser, a three dimensional finite element based numerical model is developed assuming finite speed of thermal wave propagation with two phase lags. The present work also describes the finite element formulation using phase lag boundary conditions. The numerical model is developed indigenously using an Intel fortran compiler. The transient heating and cooling phenomena are analyzed for the effect of two relaxation times, variation of pulse width, and multiple pulses. The model results are validated with ultrashort pulse laser heating of a thin gold film. The accuracy of the computed results shows promising application of the developed numerical model for differential influence of process parameters in micro/nano scale heat transport by ultrashort pulse laser processing.