TEMPERATURE DEPENDENCE CONSIDERATION ISSUE FOR COEFFICIENT OF VOLUMETRIC HEAT CAPACITY IN SIMULATION OF LASER-ARC PAD WELD PROCESS

The paper deals with research of steels and alloys melting and crystallization on the example of temperature field dynamics simulation for the laser-arc pad weld of composite materials. Mathematical model is one of the Stefan problems for nonlinear transient  three-dimensional Fourier equation of heat conduction with boundary conditions. The problem is solved by the finitedifference method with the pass-through calculation scheme. Nonlinearity of the problem is caused by the temperature dependency of the volumetric heat capacity coefficient that has a peak in the interval of phase transition (melting – crystallization). The linear-exponential approximation method is offered to consider this dependence. At some nodes of the discrete mesh the temperature changes from solid phase range to liquid phase at one time step on account of high heat velocity. The algorithm of temperature dependence consideration for volumetric heat capacity peak in the interval of melting – crystallization is suggested based on the nested mesh idea. Though the computational complexity is increased by suggested algorithm it provides more accurate solution and ensures account of phase transition phenomenon. Calculation results for linear and linear-exponential approximation of temperature dependence for volumetric heat capacity are compared. It is shown that in case of linear-exponential approximation the solution process on dynamic adaptive mesh is speeded up due to decreasing of time steps number.