The analysis of laser thermosplitting of materials by using of crescent-shaped beams

Abstract

In this paper the numerical modeling of allocation of thermoelastic fields which are formed during controllable laser thermosplitting in fragile nonmetallic materials is executed within the limits of theory of elasticity. Modelling is executed for laser beams with a cross-section in the form of an ellipse, a ring, and semi-ring and crescent beams. The classical circuit of realization of the given method consists in the superficial heating of a material by laser beam and the aftercooling of this zone by means of a refrigerating medium. Thus, the microcrack, which is organized in the zone of refrigerating medium supply, follows for a laser beam along a treatment line. On the basis of the analysis of allocation of thermoelastic fields it is displayed, that application of the classical circuit of the given method realization with the use of elliptic and ring-shaped beams possesses a number of the disadvantages, one of which is the quick deflection of a microcrack from a line of influence of a laser beam and refrigerating medium at treatment close to collateral border of the sample. Thus, the microcrack is progressed in a direction to collateral border of the sample. It is displayed, that application of crescent beams allows diminishing degree of effects of treatment line closeness to boundary line of the sample on microcrack development. The positive effect is attained due to forming a compression stress zone not only ahead and under the field of a refrigerating medium effects where the microcrack is initialized and explicated, but also on each side of zone of a refrigerating medium effects, that in its turn does not allow a microcrack to be deflected aside.