Analysis of laser welding process with the mathematical model GMDH

The employment of laser system for very automatized welding processes needs an analysis of physic mechanisms by means of mathematical models that correlate the characteristic quality index of welding to working parameters.In this work we used the Group Method of Data Handling (GMDH) mathematical model in order to correlate, for different kinds of steel, the penetration depth to working parameters, chemical composition and thermal properties of the material.The method employs an easy mathematical instrument, such as the polynomial, to create, thanks to the structural pattern of development it is founded upon, an optimal model of the process which could be very complex. The complexity of the optimal describing multinomial which was produced is, as a matter of fact, deeply linked to the complexity of the phenomenon itself.Results showed the very important influence of material composition which, in some cases, can be related to that of the main parameters as beam power and welding speed.