梯度涂层界面裂纹蠕变扩展驱动力的研究

目前针对梯度材料力学性能的研究主要集中在弹性解范围，这些研究结果尚无法直接用来关联梯度涂层的高温服役行为。文中在考虑梯度涂层不同蠕变参量的基础上，采用非均匀有限元法对梯度涂层／基体系统中的界面裂纹进行研究，通过对其高温蠕变行为的模拟计算，得到涂层梯度因子、蠕变系数、蠕变指数以及涂层厚度对裂纹蠕变扩展驱动力的影响关系，为高温下梯度涂层的优化设计奠定了一定的基础。

STUDY ON INTERFACE CREEP CRACK DRIVING FORCE OF FUNCTIONALLY GRADED COATING

Up to now, the investigation of mechanical behaviour of functionally graded material has been largely focused on the elastic solution. However the functionally graded coating (FGC) is usually employed at high temperature environment and the inelastic behavior of FGC must be involved. Thus the above mentioned research findings can not be directly utilized to guide the design of functionally graded coating. An inhomogeneous finite element method is used to investigate the interface crack behavior in FGC system under the steady creep condition. The crack energy release rate of FGC is systematically calculated according to the different volume fractions of coating material, creep coefficients, creep indices and the coating thickness. The relationships between these factors and the crack growth driving force are analyzed. Furthermore, the basis of the optimum design of FGC is also discussed.