Thermoschockrißbildung durch laserinduzierte Hochtemperaturrelaxation

Abstract

Crack formation by thermal shocks is usually discussed on the base of thermal-elastic misfits and corresponding reversible stress fields notwithstanding the fact that dangerous tensile stresses in this case are only produced by thermal quenching. The cracking by temperature peaks in high temperature applications is caused by relaxation processes on the high temperature level leading to permanent tensile stresses after cooling. The underlying processes are theoretically investigated for the case of carbon materials irradiated by short laser pulses. Temperature and stress fields and the corresponding stress intensities are calculated. The crack propagation is discussed in the framework of linear fracture mechanics