基于一维应力松弛模型和粘弹性本构关系,对1.06μm连续激光照射下K9玻璃板中的温升和应力作了计算,结果表明,由于应力松弛效应,激光停照后的冷却过程中产生的残余拉伸应力可达到玻璃的拉伸断裂强度阈值,而激光加热期间的最大压缩应力却小于压缩断裂强度要求.对3mm厚的K9玻璃板,由应力松弛引起破坏所要求的激光参数为946kWcm²作用0.2s,因而应力松弛可能为1.06μm连续激光大光斑照射下K9玻璃窗口损伤的主要模式.

Based on the stressrelaxation model in 1D planar geometry and the visco-elastic constitutive equation,thetemperature and stress histories in the K9 glass samples irradiated by CW laser beams (λ＝1.06μm)　have been calculated.The results indicate that the residualtensile stress due to the stress relaxation effect during cooling after the laserradiation may be greater than the tensile fracture strength of samples,while the maximumcompression stress during the laser heating is less than the requirement for compressiondamage.For a K9 glass window of 3mm thickness,its damage due to the stress relaxationmay be induced by a laser radiation of 0.946MW/cm² for 0.2s.Therefore,thestress relaxation should be regarded as the main mechanism of damage in K9 glass windowswhile a CW laser beam (λ＝1.06μm)　irradiates it with large spot.