Bending-driven failure mechanism and modelling of double-ceramic-layer thermal barrier coating system

INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES

卷:130

Article

Jiang, Peng¹  Fan, Xueling¹  Sun, Yongle²  Li, Dingjun¹  Wang, Tiejun¹ 

[1] Xi An Jiao Tong Univ, Sch Aerosp Engn, State Key Lab Strength & Vibrat Mech Struct, Xian 710049, Shaanxi, Peoples R China

[2] Univ Manchester, Sch Mech Aerosp & Civil Engn, Sackville St, Manchester M13 9PL, Lancs, England

关键词: Double-ceramic-layer;    Thermal barrier coating system;    Critical crack density;    Multi-cracking;    Fracture mechanics;    Failure map;   

DOI  :  10.1016/j.ijsolstr.2017.10.024

来源: Elsevier

【 摘 要 】

Bending-driven failure test is an effective and efficient method to evaluate the quality and load-bearing capacity of a thermal barrier coating (TBC) system. In this study, the failure mechanism of a double ceramic-layer TBC (DCL-TBC) system was investigated experimentally and analytically. First, a series of in-situ four-point bending tests were conducted on DCL-TBC system with the two ceramic layers having different thickness ratios. A cracking phenomenon was observed, i.e. vertical cracks (visible on the surface) and interfacial cracks (invisible unless sectioned) simultaneously evolved, from which a concept of critical vertical crack density associated with interfacial crack propagation was proposed to evaluate the bending-driven failure of DCL-TBC system. Second, an analytical model was developed to predict the critical crack density, which was based on a modified shear-lag model and interfacial fracture mechanics. The analytical prediction agreed well with the experimental results. Third, the analytical model was used to establish the failure maps of DCL-TBC system with respect to a series of physical and geometrical parameters in dimensionless form, considering both multiple surface cracking (i.e., vertical cracks) and interfacial cracking. The mechanism-based analytical approach, which has been validated by experimental results, may be used to provide a better evaluation of the damage of DCL-TBC system under bending. (C) 2017 Elsevier Ltd. All rights reserved.

【 授权许可】

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