3D modeling of material heating with the laser beam for cylindrical geometry

Abstract

In this work an analytical approach for analyzing heating of material with a laser beam is presented. A thermal model of interaction for the case of cylindrical geometry of the material and asymmetric distribution of the laser beam intensity is used and an analytical procedure is developed to analyze the temporal and the spatial distribution of the temperature field inside the bulk of material. This kind of consideration is of practical interest in cases where the excitation by the laser beam is not symmetric in respect to its position or shape, e.g., multi-mode working regimes or asymmetrical distribution of the laser beam intensity. The heating effects were considered in the temperature range up to the melting point. The thermal and the optical parameters of the material were assumed to be independent of the temperature and were given constant values in the temperature range of interest. This approach makes use of the Laplace transform, in order to eliminate dependence on time. The Fourier method of variable separation was used to obtain the temperature field distribution in the Laplace transform domain. By using the pulse response and Duhamel's principle the 3D temperature field distribution in time domain is obtained. By using an appropriate set of orthogonal functions in r directions, the numerical procedure is made more effective, saving this way the CPU time. The general solutions for the temporal as well as spatial temperature field distributions are evaluated in a closed form in terms of the particular solutions of the governing partial differential equation (PDE). Because of linearity of the governing PDE, the superposition principle was used in the case of complex distributions of the laser beam intensity. The influence of different kinds of laser beam parameters to the temperature field distributions was considered.