A semi-analytical model for predicting stress evolution in multilayer coating systems during thermal cycling
A semi-analytical model for predicting stress evolution in multilayer coating systems during thermal cycling
复制标题
用于预测热循环过程中多层涂层系统应力演变的半解析模型
DOI：
10.1016/j.ijmecsci.2017.11.010
复制
发表时间：
2018-01-01
影响因子：
7.3
通讯作者：
Wang, Tiejun
中科院分区：
文献类型：
--
作者：
Li, Biao;Fan, Xueling;Wang, Tiejun
建立了一个半解析模型来预测多层涂层系统在循环热载荷作用下的应力演化。该模型考虑了高温防护涂层常见的热条件，即沿系统厚度方向的温度梯度。在理论框架中考虑了高温下的蠕变变形和氧化皮生长过程。分析了热障涂层的情况，并进行了有限元分析比较。结果表明，半解析法求解的应力场和蠕变应变场与有限元预测结果吻合较好，验证了所建模型的有效性。讨论了系统中蠕变对应力和曲率演化的影响。结果发现，在涂层或基体中的大蠕变速率可以促进在它们两者中的应力松弛过程，而在氧化皮中的应力演变几乎不受影响。在热循环过程中，当涂层发生快速蠕变弛豫时，系统的曲率可能由凹向凸反转。此外，氧化皮中的蠕变变形提供了缓解巨大的生长应力的益处，从而可以获得更好的耐久性。(C)2017爱思唯尔有限公司版权所有
A semi-analytical model is developed to predict the stress evolution within a multilayer coating system during cyclic thermal loading. This model takes into account the temperature gradient across the thickness of the system, which is the common thermal conditions of the high-temperature protective coatings. The creep deformation and the oxide scale growth processes at the elevated temperature are considered in the theoretical framework. The cases of thermal barrier coatings are analyzed, and finite element analysis is performed for comparisons. The results show that the stress and creep strain fields solved by the semi-analytical method are consistent with the finite element predictions, which confirms the validity of the proposed model. The effects of creep in the system on the stresses and curvature evolutions are discussed. It is found that the large creep rates in the coatings or substrate could facilitate the stress relaxation processes in both of them, whereas the stress evolutions in the oxide scale are virtually unaffected. The curvature of the system may reverse from the concave to convex shape during the thermal cycling when the fast creep relaxations occur in the coatings. Furthermore, the creep deformations in the oxide scale provide benefits in relaxing the huge growth stresses so that the better durability of the system could be obtained. (C) 2017 Elsevier Ltd. All rights reserved.