硫化锌热冲击试验与裂纹间距预报

摘要

Crack spacing and depth prediction of ZnS materials were studied under thermal shock.The gas rapid heating experiment showed that crack spacing of ZnS specimens with 10mm thickness decreased with increasing heat flux.During the thermal shock,heating surface of specimen firstly appeared non-penetrated cracks.After the heating stopped,cracks penetrated specimen.The transient temperature field and stress field were calculated by finite element analysis,and the cracking mechanism of ZnS under thermal shock was studied.A simplified shear lag analysis using a progressive scheme was proposed for ZnS,and a theoretical method for predicting thermal shock crack spacing was developed by using the minimum energy principle with the crack spacing and depth as variables.The influences of fracture toughness,thermal expansion coefficient and elastic modulus on crack spacing and depth were analyzed.Result shows that reduced modulus and thermal expansion coefficient,increased fracture toughness contribute to improving the performance under thermal shock.The present research provides deeper understanding of the failure mechanism of ZnS under thermal shock,improving the performance and designing new ZnS.%重点研究了硫化锌热冲击开裂机理和热冲击裂纹间距、深度的预报.10mm厚硫化锌试块的燃气急热试验表明:裂纹间距随热冲击能量的增大而减小,热冲击过程中加热面最先出现非贯穿裂纹,停止加热后,裂纹贯穿试件.结合传热和热强度仿真分析,获得了热冲击过程中试件的瞬态温度场和应力场.基于材料性能的损伤演化理论,以裂纹间距和深度为变量,利用最小能量原理,获得了热冲击裂纹间距的理论预报方法,预测结果与试验吻合较好,进而分析了断裂韧性、热胀系数、材料初始模量对裂纹间距、裂纹深度的影响.该文的研究对深入理解硫化锌的热冲击失效机制,对其改性和研制具有重要意义.