孔隙对热障涂层微压痕响应影响的数值模拟

Numerical Simulation on Effect of Pores on Micro-Compression Mechanical Response ofThermal Barrier Coatings

微纳米压痕技术是表征陶瓷涂层系统力学性能和弹塑性响应行为的一项重要技术。通过Python二次开发在ABAQUS软件中建立含随机分布的圆形孔隙的热障涂层模型,研究孔隙对大气等离子法(APS)制备的热障涂层的微纳米压痕响应的影响,并在含随机圆形孔隙热障涂层模型的基础上,利用扩展有限元法(XFEM)模拟分析微纳米压痕试验过程中陶瓷层内的裂纹扩展,探究微裂纹和孔隙间的相互影响,以及涂层内裂纹萌生扩展的规律。模拟结果表明,孔隙的存在会在加载和卸载过程中释放一定的应力集中,从而改变涂层应力的分布特征;孔隙的存在会导致裂纹向孔隙的方向偏移扩展,并在一定程度上阻止裂纹扩展。将这些工作与微纳米压痕试验的试验数据联系起来,可以对热障涂层体系的力学性能进行有效预测。

Micro/nano-indentation is a very important technique to characterize the mechanical properties and elastic/plastic response behavior of ceramic coatings system.A thermal barrier coating model containing randomly distributed circular pores was developed in ABAQUS using a secondary development plugin Python to investigate the effect of pores on the micro/nano-indentation response of thermal barrier coatings prepared by atmospheric plasma spraying(APS).Based on a finite element model of a thermal barrier coating containing random circular pores,the extended finite element method was used to simulate and analyze the crack propagation within the ceramic layer during the micro/nanoindentation experiments,and to further investigate the interaction between micro-cracks and pores,and the patterns of crack emergence and propagation within the coating.The results show that the distribution characteristic of the residual stress could be changed due to existence of the pores because the pores would release some stress concentration more or less during the loading and unloading processes.The presence of pores in the ceramic layer caused cracks to propagate in the direction of the pores and prevented crack further propagate to some extent.Correlating this work with the experimental results from micro/nano-indentation experiments may help us to predict the actual mechanical properties of thermal barrier coating systems.