热冲击作用下的陶瓷材料破裂过程数值分析

运用热传导和热2力耦合的相关理论 , 借助统计分布来考虑陶瓷中存在的微孔洞和微裂隙 ; 建立了一种可以模拟陶瓷遭受热冲击作用下的裂纹萌生、 扩展过程的数值模拟方法 , 并通过材料破坏过程分析系统 (RF2PA , Realistic Failure Process Analysis) 加以实施。该数值方法基于细观非均匀性假设 , 突破了以往连续介质力学视陶瓷为均匀介质的假设 , 并从细观损伤角度考虑陶瓷热冲击破坏演化的过程。运用该方法对三面绝热、 一面受热冲击的平板状陶瓷材料的破裂过程进行了数值试验。结果表明 : 起始裂纹发端于受热冲击表面 , 且在初始的裂纹萌生阶段 , 在受热冲击表面产生一系列无序的裂纹 ; 但随着时间的延续 , 裂纹逐渐演变成多条近乎平行的、沿受冲击表面内法向方向扩展的主裂纹 , 其中一些裂纹的发展受到了屏蔽 , 这一结果与试验结果吻合较好。本数值方法为相关研究提供了新的思路。 

Failure process analysis of ceramic materials subjected to thermal shock

A thermo-mechanical model for ceramic materials subjected to thermal shock is presented in this paper . The model was based on the thermo-mechanical coupling principle , and the statistical method was used to consider the heterogeneity of ceramics at the mesoscopic level , which is different f rom the previous models based on the so-called continuous damage mechanics. The failure process of plane ceramics subjected to thermal shock was investigated to validate this model and also to reveal the failure mechanism of ceramic materials under the thermal condition. The results show that the cracks are initiated ruleless on the surface where it is subjected to thermal shock at the beginning of the thermal shock. However , with the further thermal conduction some cracks gradually grow in the inner normal direction of the surface while the propagation of other cracks is rest rained. The results well agree with the experimental data. The proposed approach provides a new method to model the failure process of ceramic materials subjected to thermal shock.