Thermal fracture characteristics induced by laser beam

The damage mechanism of a cracked material due to laser beam thermal shock is an important problem when the interactions of high power laser beam with materials are studied. The transient thermal stress intensity factors (TSI Fs) for a center crack in an infinite plate subjected to laser beam thermal shock are investigated. When the crack is in the heat affected zone, the c ompressive thermal stress causes the crack surface to come into contact wit h each other over a certain contact length, but the high tensile stresses a round the crack tip tend to open the crack. In this case, the problem may b e treated as a pair of embedded cracks problem with a smooth closure condit ion of the center crack. The TSIFs and the crack contact lengths are calcul ated with different laser beam spatial shapes. The TSIFs induced by thermal shock are in marked different from those induced by general mechanical loa ding. (C) 2001 Elsevier Science Ltd. AII rights reserved.