多层膜结构热应力计算

THERMAL STRESSES IN ELASTIC MULTILAYER SYSTEMS

多层保护膜结构在光学窗口等领域有广泛应用,其中膜层中的热应力对系统的功能和可靠性有重要影响.推导了条形多层薄膜结构系统中应力应变的计算方法,并针对薄膜厚度远小于基底厚度的薄膜结构计算进行了相应的简化,得到了其一阶近似以及零阶近似应力的计算公式.采用此公式对ZnS--Y2O3--SiO2双层膜系红外窗口系统进行了求解分析.计算结果显示,热应力在两层薄膜上的相对误差分别为1.54%和0.09%,零阶近似可以很好地满足计算精度要求.

Multilayer systems are widely used in the infrared widow system. Thermal stresses in the thin films are very important to the functions and reliability of the system. In this paper, the strain and stress distributions in an elastic multilayered strip are calculated. The first-order approximation and the zero-order approximation solutions are proposed for the system when the thicknesses of the film layers are much less than the substrate thickness. Specific results are calculated for the elastic thermal stresses in the ZnS-Y2O3-SiO2 infrared window. The results show that the thermal stresses based on the first-order approximation and the zero-order approximation in two film layers have a relative error about 1.54% and 0.09%, respectively. The zero-order approximation solutions can meet the accuracy requirement very well.