Stress relaxation damage in K9 glass plate irradiated by 1.06m m CW laser

Based on the stress relaxation model in 1D planar geometry and the visco-elastic constitutive equation, the temperature and stress histories in the K9 glass samples irradiated by CW lser beams (l =1.06μｍ) have been calculated in this paper. The results indicate that the residual tensile stress due to the stress relaxation effect during cooling after the laser radiation may be greater than the tensile fracture strength of samples, while the maximum compression stress during the laser heating is less than the requirement for compression damage. For a K9 glass window of 3mm thickness, its damage due to the stress relaxation may be induced by a laser radiation of 946kW/cm2 for 0.2s. Therefore, the stress relaxation should be regarded as the main mechanism of damage in K9 glass windows while